Search

PURPOSE Survivors of hereditary retinoblastoma have excellent survival but substantially increased risks of subsequent bone and soft-tissue sarcomas, particularly after radiotherapy. Comprehensive investigation of sarcoma risk patterns would inform clinical surveillance for survivors. PATIENTS AND METHODS In a cohort of 952 irradiated survivors of hereditary retinoblastoma who were originally diagnosed during 1914 to 2006, we quantified sarcoma risk with standardized incidence ratios (SIRs) and cumulative incidence analyses. We conducted analyses separately for bone and soft-tissue sarcomas occurring in the head and neck (in/near the radiotherapy field) versus body and extremities (out of field). RESULTS Of 105 bone and 124 soft-tissue sarcomas, more than one half occurred in the head and neck (bone, 53.3%; soft tissue, 51.6%), one quarter in the body and extremities (bone, 29.5%; soft tissue, 25.0%), and approximately one fifth in unknown/unspecified locations (bone, 17.1%; soft tissue, 23.4%). We noted substantially higher risks compared with the general population for head and neck versus body and extremity tumors for both bone (SIR, 2,213; 95% CI, 1,671 to 2,873 v SIR, 169; 95% CI, 115 to 239) and soft-tissue sarcomas (SIR, 542; 95% CI, 418 to 692 v SIR, 45.7; 95% CI, 31.1 to 64.9). Head and neck bone and soft-tissue sarcomas were diagnosed beginning in early childhood and continued well into adulthood, reaching a 60-year cumulative incidence of 6.8% (95% CI, 5.0% to 8.7%) and 9.3% (95% CI, 7.0% to 11.7%), respectively. In contrast, body and extremity bone sarcoma incidence flattened after adolescence (3.5%; 95% CI, 2.3% to 4.8%), whereas body and extremity soft-tissue sarcoma incidence was rare until age 30, when incidence rose steeply (60-year cumulative incidence, 6.6%; 95% CI, 4.1% to 9.2%), particularly for females (9.4%; 95% CI, 5.1% to 13.8%). CONCLUSION Strikingly elevated bone and soft-tissue sarcoma risks differ by age, location, and sex, highlighting important contributions of both radiotherapy and genetic susceptibility. These data provide guidance for the development of a risk-based screening protocol that focuses on the highest sarcoma risks by age, location, and sex.

Background Ionizing radiation is an established carcinogen, but risks from low-dose exposures are controversial. Since the Biological Effects of Ionizing Radiation VII review of the epidemiological data in 2006, many subsequent publications have reported excess cancer risks from low-dose exposures. Our aim was to systematically review these studies to assess the magnitude of the risk and whether the positive findings could be explained by biases. Methods Eligible studies had mean cumulative doses of less than 100 mGy, individualized dose estimates, risk estimates, and confidence intervals (CI) for the dose-response and were published in 2006–2017. We summarized the evidence for bias (dose error, confounding, outcome ascertainment) and its likely direction for each study. We tested whether the median excess relative risk (ERR) per unit dose equals zero and assessed the impact of excluding positive studies with potential bias away from the null. We performed a meta-analysis to quantify the ERR and assess consistency across studies for all solid cancers and leukemia. Results Of the 26 eligible studies, 8 concerned environmental, 4 medical, and 14 occupational exposure. For solid cancers, 16 of 22 studies reported positive ERRs per unit dose, and we rejected the hypothesis that the median ERR equals zero (P = .03). After exclusion of 4 positive studies with potential positive bias, 12 of 18 studies reported positive ERRs per unit dose (P = .12). For leukemia, 17 of 20 studies were positive, and we rejected the hypothesis that the median ERR per unit dose equals zero (P = .001), also after exclusion of 5 positive studies with potential positive bias (P = .02). For adulthood exposure, the meta-ERR at 100 mGy was 0.029 (95% CI = 0.011 to 0.047) for solid cancers and 0.16 (95% CI = 0.07 to 0.25) for leukemia. For childhood exposure, the meta-ERR at 100 mGy for leukemia was 2.84 (95% CI = 0.37 to 5.32); there were only two eligible studies of all solid cancers. Conclusions Our systematic assessments in this monograph showed that these new epidemiological studies are characterized by several limitations, but only a few positive studies were potentially biased away from the null. After exclusion of these studies, the majority of studies still reported positive risk estimates. We therefore conclude that these new epidemiological studies directly support excess cancer risks from low-dose ionizing radiation. Furthermore, the magnitude of the cancer risks from these low-dose radiation exposures was statistically compatible with the radiation dose-related cancer risks of the atomic bomb survivors.

Background There is international consensus that benzene exposure is causally related to acute myeloid leukemia (AML), and more recent evidence of association with myelodysplastic syndromes (MDS). However, there are uncertainties about the exposure response, particularly risks by time since exposure and age at exposure. Methods In a case–cohort study in 110 631 Chinese workers followed up during 1972–1999 we evaluated combined MDS/AML (n = 44) and chronic myeloid leukemia (n = 18). We estimated benzene exposures using hierarchical modeling of occupational factors calibrated with historical routine measurements, and evaluated exposure response for cumulative exposure and average intensity using Cox regression; P values were two-sided. Results Increased MDS/AML risk with increasing cumulative exposure in our a priori defined time window (2 to Conclusion For myeloid neoplasms, the strongest effects were apparent for MDS/AML arising within 10 years of benzene exposure and for first exposure in the 2 to less than 10-year window before age 30 years.

Purpose To compare total and cause-specific mortality rates between physicians likely to have performed fluoroscopy-guided interventional (FGI) procedures (referred to as FGI MDs) and psychiatrists to determine if any differences are consistent with known radiation risks. Materials and Methods Mortality risks were compared in nationwide cohorts of 45 634 FGI MDs and 64 401 psychiatrists. Cause of death was ascertained from the National Death Index. Poisson regression was used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for FGI MDs versus psychiatrists, with adjustment (via stratification) for year of birth and attained age. Results During follow-up (1979-2008), 3506 FGI MDs (86 women) and 7814 psychiatrists (507 women) died. Compared with psychiatrists, FGI MDs had lower total (men: RR, 0.80 [95% CI: 0.77, 0.83]; women: RR, 0.80 [95% CI: 0.63, 1.00]) and cancer (men: RR, 0.92 [95% CI: 0.85, 0.99]; women: RR, 0.83 [95% CI: 0.58, 1.18]) mortality. Mortality because of specific types of cancer, total and specific types of circulatory diseases, and other causes were not elevated in FGI MDs compared with psychiatrists. On the basis of small numbers, leukemia mortality was elevated among male FGI MDs who graduated from medical school before 1940 (RR, 3.86; 95% CI: 1.21, 12.3). Conclusion Overall, total deaths and deaths from specific causes were not elevated in FGI MDs compared with psychiatrists. These findings require confirmation in large cohort studies with individual doses, detailed work histories, and extended follow-up of the subjects to substantially older median age at exit. © RSNA, 2017 Online supplemental material is available for this article.

Whether low-dose ionizing radiation can cause cancer is a critical and long-debated question in radiation protection. Since the Biological Effects of Ionizing Radiation report by the National Academies in 2006, new publications from large, well-powered epidemiological studies of low doses have reported positive dose-response relationships. It has been suggested, however, that biases could explain these findings. We conducted a systematic review of epidemiological studies with mean doses less than 100 mGy published 2006–2017. We required individualized doses and dose-response estimates with confidence intervals. We identified 26 eligible studies (eight environmental, four medical, and 14 occupational), including 91 000 solid cancers and 13 000 leukemias. Mean doses ranged from 0.1 to 82 mGy. The excess relative risk at 100 mGy was positive for 16 of 22 solid cancer studies and 17 of 20 leukemia studies. The aim of this monograph was to systematically review the potential biases in these studies (including dose uncertainty, confounding, and outcome misclassification) and to assess whether the subset of minimally biased studies provides evidence for cancer risks from low-dose radiation. Here, we describe the framework for the systematic bias review and provide an overview of the eligible studies.

Purpose To investigate the relationship between oesophagus dose-volume distribution and long-term risk of oesophageal cancer after radiation therapy for breast cancer. Materials and methods In a case-control study nested within a cohort of 289,748 ≥5-year survivors of female breast cancer treated in 1943–2003 in five countries, doses to the second primary cancer (DSPC) and individual dose-volume histograms (DVH) to the entire oesophagus were reconstructed for 252 oesophageal cancer cases and 488 matched controls (median follow-up time: 13, range: 5–37 years). Using conditional logistic regression, we estimated excess odds ratios (EOR) of oesophageal cancer associated with DVH metrics. We also investigated whether DVH metrics confounded or modified DSPC-related -risk estimates. Results Among the DVH metrics evaluated, median dose (Dmedian) to the entire oesophagus had the best statistical performance for estimating risk of all histological types combined (EOR/Gy = 0.071, 95% confidence interval [CI]: 0.018 to 0.206). For squamous cell carcinoma, the most common subtype, the EOR/Gy for Dmedian increased by 31% (95% CI: 3% to 205%) for each increment of 10% of V30 (p = 0.02). Adjusting for DVH metrics did not materially change the EOR/Gy for DSPC, but there was a borderline significant positive interaction between DSPC and V30 (p = 0.07). Conclusion This first study investigating the relationship between oesophagus dose-volume distribution and oesophageal cancer risk showed an increased risk per Gy for Dmedian with larger volumes irradiated at high doses. While current techniques allows better oesophagus sparing, constraints applied to Dmedian and V30 could potentially further reduce the risk of oesophageal cancer.

Background: Pancreatic cancer risk is elevated among testicular cancer (TC) survivors. However, the roles of specific treatments are unclear. Methods: Among 23 982 5-year TC survivors diagnosed during 1947–1991, doses from radiotherapy to the pancreas were estimated for 80 pancreatic cancer patients and 145 matched controls. Chemotherapy details were recorded. Logistic regression was used to estimate odds ratios (ORs). Results: Cumulative incidence of second primary pancreatic cancer was 1.1% at 30 years after TC diagnosis. Radiotherapy (72 (90%) cases and 115 (80%) controls) was associated with a 2.9-fold (95% confidence interval (CI) 1.0–7.8) increased risk. The OR increased linearly by 0.12 per Gy to the pancreas (P-trend

ObjectivesTo assess radiation exposure-related work history and risk of cataract and cataract surgery among radiologic technologists assisting with fluoroscopically guided interventional procedures (FGIP).MethodsThis retrospective study included 35 751 radiologic technologists who reported being cataract-free at baseline (1994–1998) and completed a follow-up questionnaire (2013–2014). Frequencies of assisting with 21 types of FGIP and use of radiation protection equipment during five time periods (before 1970, 1970–1979, 1980–1989, 1990–1999, 2000–2009) were derived from an additional self-administered questionnaire in 2013–2014. Multivariable-adjusted relative risks (RRs) for self-reported cataract diagnosis and cataract surgery were estimated according to FGIP work history.ResultsDuring follow-up, 9372 technologists reported incident physician-diagnosed cataract; 4278 of incident cases reported undergoing cataract surgery. Technologists who ever assisted with FGIP had increased risk for cataract compared with those who never assisted with FGIP (RR: 1.18, 95% CI 1.11 to 1.25). Risk increased with increasing cumulative number of FGIP; the RR for technologists who assisted with >5000 FGIP compared with those who never assisted was 1.38 (95% CI 1.24 to 1.53; p trend 3 feet (>0.9 m) (RRs for >5000 at ≤3 feet vs never FGIP were 1.48, 95% CI 1.27 to 1.74 and 1.15, 95% CI 0.98 to 1.35, respectively; pdifference=0.04). Similar risks, although not statistically significant, were observed for cataract surgery.ConclusionTechnologists who reported assisting with FGIP, particularly high-volume FGIP within 3 feet of the patient, had increased risk of incident cataract. Additional investigation should evaluate estimated dose response and medically validated cataract type.

Although increased risk of acute myeloid leukemia (AML) has been observed after chemotherapy and radiotherapy, less is known about radiotherapy-related risks of specific AML subtypes and other specific myeloid neoplasms. We used the US population-based cancer registry data to evaluate risk of myeloid neoplasms among three cohorts of cancer survivors initially treated with radiotherapy only. We included 1-year survivors of first primary thyroid (radioiodine only, stages I–IV; N = 49 879), prostate (excluding stage IV; N = 237 439), or uterine corpus cancers (stage I–II; N = 16 208) diagnosed during 2000–2013. We calculated standardized incidence ratios (SIRs) and excess absolute risks (EARs). Thyroid cancer survivors had significantly elevated risks of total AML (SIR = 2.77, 95% CI: 1.99–3.76), AML with cytogenetic abnormalities (SIR = 3.90, 95% CI: 1.57–8.04), AML with myelodysplasia-related changes (SIR = 2.87, 95% CI: 1.05–6.25), and BCR-ABL1-positive chronic myelogenous leukemia (CML) (SIR = 5.38, 95% CI: 2.58–9.89). Irradiated prostate and uterine corpus cancer survivors were at elevated risk for total AML (SIR = 1.14, 95% CI: 1.03–1.27 and SIR = 1.77, 95% CI: 1.01–2.87, respectively), AML with cytogenetic abnormalities (SIR = 2.52, 95% CI: 1.84–3.37 and SIR = 7.21, 95% CI: 2.34–16.83, respectively), and acute promyelocytic leukemia (SIR = 3.20, 95% CI: 2.20–4.49 and SIR = 8.88, 95% CI: 2.42–22.73, respectively). In addition, prostate cancer survivors were at increased risk of BCR-ABL1-positive CML (SIR = 2.11, 95% CI: 1.52–2.85). Our findings support the importance of diagnostic precision in myeloid neoplasm classification since susceptibility following radiotherapy may vary by myeloid neoplasm subtype, thereby informing risk/benefit discussions in first primary cancer treatment.

Benzene exposure has been causally linked with acute myeloid leukemia (AML), but inconsistently associated with other hematopoietic, lymphoproliferative and related disorders (HLD) or solid tumors in humans. Many neoplasms have been described in experimental animals exposed to benzene. We used Poisson regression to estimate adjusted relative risks (RR) and the likelihood ratio statistic to derive confidence intervals for cause-specific mortality and HLD incidence in 73,789 benzene-exposed compared with 34,504 unexposed workers in a retrospective cohort study in 12 cities in China. Follow-up and outcome assessment was based on factory, medical and other records. Benzene-exposed workers experienced increased risks for all-cause mortality (RR = 1.1, 95% CI = 1.1, 1.2) due to excesses of all neoplasms (RR = 1.3, 95% CI = 1.2, 1.4), respiratory diseases (RR = 1.7, 95% CI = 1.2, 2.3) and diseases of blood forming organs (RR = ∞, 95% CI = 3.4, ∞). Lung cancer mortality was significantly elevated (RR = 1.5, 95% CI = 1.2, 1.9) with similar RRs for males and females, based on three-fold more cases than in our previous follow-up. Significantly elevated incidence of all myeloid disorders reflected excesses of myelodysplastic syndrome/acute myeloid leukemia (RR = 2.7, 95% CI = 1.2, 6.6) and chronic myeloid leukemia (RR = 2.5, 95% CI = 0.8, 11), and increases of all lymphoid disorders included excesses of non-Hodgkin lymphoma (RR = 3.9, 95%CI = 1.5, 13) and all lymphoid leukemia (RR = 5.4, 95%CI = 1.0, 99). The 28-year follow-up of Chinese benzene-exposed workers demonstrated increased risks of a broad range of myeloid and lymphoid neoplasms, lung cancer, and respiratory diseases and suggested possible associations with other malignant and non-malignant disorders.

To further understand the risk of stomach cancer after fractionated high-dose radiotherapy, we pooled individual-level data from three recent stomach cancer case-control studies. These studies were nested in cohorts of five-year survivors of first primary Hodgkin lymphoma (HL), testicular cancer (TC) or cervical cancer (CX) from seven countries. Detailed data were abstracted from patient records and radiation doses were reconstructed to the site of the stomach cancer for cases and to the corresponding sites for matched controls. Among 327 cases and 678 controls, mean doses to the stomach were 15.3 Gy, 24.7 Gy and 1.9 Gy, respectively, for Hodgkin lymphoma, testicular cancer and cervical cancer survivors, with an overall mean dose of 10.3 Gy. Risk increased with increasing radiation dose to the stomach cancer site (P < 0.001) with no evidence of nonlinearity or of a downturn at the highest doses (≥35 Gy). The pooled excess odds ratio per Gy (EOR/Gy) was 0.091 [95% confidence interval (CI): 0.036-0.20] with estimates of 0.049 (95% CI: 0.007-0.16) for Hodgkin lymphoma, 0.27 (95% CI: 0.054-1.44) for testicular cancer and 0.096 (95% CI: -0.002-0.39) for cervical cancer (P homogeneity = 0.25). The EOR/Gy increased with time since exposure (P trend = 0.004), with an EOR/Gy of 0.38 (95% CI: 0.12-1.04) for stomach cancer occurring ≥20 years postirradiation corresponding to odds ratios of 4.8 and 10.5 at radiation doses to the stomach of 10 and 25 Gy, respectively. Of 111 stomach cancers occurring ≥20 years after radiotherapy, 63.8 (57%) could be attributed to radiotherapy. Our findings differ from those based on Japanese atomic-bomb survivors, where the overall EOR/Gy was higher and where there was no evidence of an increase with time since exposure. By pooling data from three studies, we demonstrated a clear increase in stomach cancer risk over a wide range of doses from fractionated radiotherapy with the highest risks occurring many years after exposure. These findings highlight the need to directly evaluate the health effects of high-dose fractionated radiotherapy rather than relying on the data of persons exposed at low and moderate acute doses.

Although elevated risks of pancreatic cancer have been observed in long-term survivors of Hodgkin lymphoma (HL), no prior study has assessed the risk of second pancreatic cancer in relation to radiation dose and specific chemotherapeutic agents.We conducted an international case-control study within a cohort of 19 882 HL survivors diagnosed from 1953 to 2003 including 36 cases and 70 matched controls.Median ages at HL and pancreatic cancer diagnoses were 47 and 60.5 years, respectively; median time to pancreatic cancer was 19 years. Pancreatic cancer risk increased with increasing radiation dose to the pancreatic tumor location (Ptrend = 0.005) and increasing number of alkylating agent (AA)-containing cycles of chemotherapy (Ptrend = 0.008). The odds ratio (OR) for patients treated with both subdiaphragmatic radiation (≥10 Gy) and ≥6 AA-containing chemotherapy cycles (13 cases, 6 controls) compared with patients with neither treatment was 17.9 (95% confidence interval 3.5-158). The joint effect of these two treatments was significantly greater than additive (P = 0.041) and nonsignificantly greater than multiplicative (P = 0.29). Especially high risks were observed among patients receiving ≥8400 mg/m(2) of procarbazine with nitrogen mustard or ≥3900 mg/m(2) of cyclophosphamide.Our study demonstrates for the first time that both radiotherapy and chemotherapy substantially increase pancreatic cancer risks among HL survivors treated in the past. These findings extend the range of nonhematologic cancers associated with chemotherapy and add to the evidence that the combination of radiotherapy and chemotherapy can lead to especially large risks.

Advances in Hodgkin lymphoma (HL) treatment have dramatically improved prognosis, with 5-year relative survival now over 80% in the United States (US) and Europe. However, subsequent malignancies, often occurring as late adverse effects of treatment, are a leading cause of morbidity and mortality

Purpose To evaluate effects of radiation therapy, chemotherapy, cigarette smoking, and alcohol consumption on the risk of second primary salivary gland cancer (SGC) in the Childhood Cancer Survivor Study (CCSS). Methods and Materials Standardized incidence ratios (SIR) and excess absolute risks (EAR) of SGC in the CCSS were calculated using incidence rates from Surveillance, Epidemiology, and End Results population-based cancer registries. Radiation dose to the salivary glands was estimated based on medical records. Poisson regression was used to assess risks with respect to radiation dose, chemotherapy, smoking, and alcohol consumption. Results During the time period of the study, 23 cases of SGC were diagnosed among 14,135 childhood cancer survivors. The mean age at diagnosis of the first primary cancer was 8.3 years, and the mean age at SGC diagnosis was 24.8 years. The incidence of SGC was 39-fold higher in the cohort than in the general population (SIR = 39.4; 95% CI = 25.4-57.8). The EAR was 9.8 per 100,000 person-years. Risk increased linearly with radiation dose (excess relative risk = 0.36/Gy; 95% CI = 0.06-2.5) and remained elevated after 20 years. There was no significant trend of increasing risk with increasing dose of chemotherapeutic agents, pack-years of cigarette smoking, or alcohol intake. Conclusion Although the cumulative incidence of SGC was low, childhood cancer survivors treated with radiation experienced significantly increased risk for at least 2 decades after exposure, and risk was positively associated with radiation dose. Results underscore the importance of long-term follow up of childhood cancer survivors for the development of new malignancies.

The Chernobyl accident, which occurred April 26, 1986, resulted in a large release of radionuclides, which were deposited over a very wide area, particularly in Europe. Although an increased risk of thyroid cancer in exposed children has been clearly demonstrated in the most contaminated regions, the impact of the accident on the risk of other cancers as well as elsewhere in Europe is less clear. The objective of the present study was to evaluate the human cancer burden in Europe as a whole from radioactive fallout from the accident. Average country- and region-specific whole-body and thyroid doses from Chernobyl were estimated using new dosimetric models and radiological data. Numbers of cancer cases and deaths possibly attributable to radiation from Chernobyl were estimated, applying state-of-the-art risk models derived from studies of other irradiated populations. Simultaneously, trends in cancer incidence and mortality were examined over time and by dose level. The risk projections suggest that by now Chernobyl may have caused about 1,000 cases of thyroid cancer and 4,000 cases of other cancers in Europe, representing about 0.01% of all incident cancers since the accident. Models predict that by 2065 about 16,000 (95% UI 3,400-72,000) cases of thyroid cancer and 25,000 (95% UI 11,000-59,000) cases of other cancers may be expected due to radiation from the accident, whereas several hundred million cancer cases are expected from other causes. Although these estimates are subject to considerable uncertainty, they provide an indication of the order of magnitude of the possible impact of the Chernobyl accident. It is unlikely that the cancer burden from the largest radiological accident to date could be detected by monitoring national cancer statistics. Indeed, results of analyses of time trends in cancer incidence and mortality in Europe do not, at present, indicate any increase in cancer rates -- other than of thyroid cancer in the most contaminated regions -- that can be clearly attributed to radiation from the Chernobyl accident.

Risk projection methods allow for timely assessment of the potential magnitude of radiation-related cancer risks following low-dose radiation exposures. The estimation of such risks directly through observational studies would generally require infeasibly large studies and long-term follow-up to achieve reasonable statistical power. We developed an online radiation risk assessment tool (RadRAT) which can be used to estimate the lifetime risk of radiation-related cancer with uncertainty intervals following a user-specified exposure history (https://irep.nci.nih.gov/radrat). The uncertainty intervals constitute a key component of the program because of the various assumptions that are involved in such calculations. The risk models used in RadRAT are broadly based on those developed by the BEIR VII committee for estimating lifetime risk following low-dose radiation exposure of the US population for eleven site-specific cancers. We developed new risk models for seven additional cancer sites, oral, oesophagus, gallbladder, pancreas, rectum, kidney and brain/central nervous system (CNS) cancers, using data from Japanese atomic bomb survivors. The lifetime risk estimates are slightly higher for RadRAT than for BEIR VII across all exposure ages mostly because the weighting of the excess relative risk and excess absolute risk models was conducted on an arithmetic rather than a logarithmic scale. The calculator can be used to estimate lifetime cancer risk from both uniform and non-uniform doses that are acute or chronic. It is most appropriate for low-LET radiation doses < 1 Gy, and for individuals with life-expectancy and cancer rates similar to the general population in the US.

Exposure to radioactive iodine ((131)I) from atmospheric nuclear tests conducted in Nevada in the 1950s may have increased thyroid cancer risks. To investigate the long-term effects of this exposure, we analyzed data on thyroid cancer incidence (18,545 cases) from eight Surveillance, Epidemiology, and End Results (SEER) tumor registries for the period 1973-2004. Excess relative risks (ERR) per gray (Gy) for exposure received before age 15 were estimated by relating age-, birth year-, sex- and county-specific thyroid cancer rates to estimates of cumulative dose to the thyroid that take age into account. The estimated ERR per Gy for dose received before 1 year of age was 1.8 [95% confidence interval (CI), 0.5-3.2]. There was no evidence that this estimate declined with follow-up time or that risk increased with dose received at ages 1-15. These results confirm earlier findings based on less extensive data for the period 1973-1994. The lack of a dose response for those exposed at ages 1-15 is inconsistent with studies of children exposed to external radiation or (131)I from the Chernobyl accident, and results need to be interpreted in light of limitations and biases inherent in ecological studies, including the error in doses and case ascertainment resulting from migration. Nevertheless, the study adds support for an increased risk of thyroid cancer due to fallout, although the data are inadequate to quantify it.

Background: Adjuvant radiotherapy is common for uterine corpus cancer patients, yet the long-term carcinogenic effects of different types of radiotherapy have not been studied adequately. Methods: Second primary cancer risks were quantified in a cohort of 60,949 individuals surviving ≥1 year of uterine corpus cancer diagnosed from 1973 to 2003 in Surveillance, Epidemiology and End Results Program cancer registries. Incidence rate ratios (IRR) were estimated by comparing patients treated with surgery plus various types of radiotherapy with patients receiving surgery only. Results: The IRRs of a second cancer were increased among irradiated patients compared with patients having surgery only [combination radiotherapy, IRR = 1.26; 95% confidence interval (CI), 1.16-1.36; external beam therapy, IRR = 1.15; 95% CI CI, 1.08-1.22; brachytherapy, IRR = 1.07; 95% CI, 1.00-1.16]. IRRs were highest for heavily irradiated sites (that is colon, rectum, and bladder) and for leukemia following any external beam therapy, with the largest risks for solid cancers among 10-year survivors. Any external beam therapy had a 44% higher cancer risk at heavily irradiated sites than brachytherapy when the two treatments were directly compared (5-year survivors: IRR = 1.44; 95% CI, 1.19-1.75). We estimated that of 2,012 solid cancers developing ≥5 years after irradiation, 213 (11%) could be explained by radiotherapy. Conclusions: Radiotherapy for uterine cancer increases the risk of leukemia and second solid cancers at sites in close proximity to the uterus, emphasizing the need for continued long-term surveillance for new malignancies. The overall risk of a second cancer was lower following brachytherapy compared with any external beam radiotherapy. Cancer Epidemiol Biomarkers Prev; 19(2); 464–74

Epidemiologic studies of persons exposed to ionising radiation offer a wealth of information on cancer risks in humans. The Life Span Study cohort of Japanese A-bomb survivors, a large cohort that includes all ages and both sexes with a wide range of well-characterised doses, is the primary resource for estimating carcinogenic risks from low linear energy transfer external exposure. Extensive data on persons exposed for therapeutic or diagnostic medical reasons offer the opportunity to study fractionated exposure, risks at high therapeutic doses, and risks of site-specific cancers in non-Japanese populations. Studies of persons exposed for occupational and environmental reasons allow a direct evaluation of exposure at low doses and dose rates, and also provide information on different types of radiation such as radon and iodine-131. This article summarises the findings from these studies with emphasis on studies with well-characterised doses.Epidemiologic studies provide the necessary data for quantifying cancer risks as a function of dose and for setting radiation protection standards. Leukaemia and most solid cancers have been linked with radiation. Most solid cancer data are reasonably well described by linear-dose response functions although there may be a downturn in risks at very high doses. Persons exposed early in life have especially high relative risks for many cancers, and radiation-related risk of solid cancers appears to persist throughout life.

Workers at the Mayak nuclear facility in the Russian Federation offer the only adequate human data for evaluating cancer risks from exposure to plutonium. Risks of mortality from cancers of the lung, liver and bone, the organs receiving the largest doses from plutonium, were evaluated in a cohort of 17,740 workers initially hired 1948-1972 using, for the first time, recently improved individual organ dose estimates. Excess relative risk (ERR) models were used to evaluate risks as functions of internal (plutonium) dose, external (primarily gamma) dose, gender, attained age and smoking. By December 31, 2003, 681 lung cancer deaths, 75 liver cancer deaths and 30 bone cancer deaths had occurred. Of these 786 deaths, 239 (30%) were attributed to plutonium exposure. Significant plutonium dose-response relationships (p < 0.001) were observed for all 3 endpoints, with lung and liver cancer risks reasonably described by linear functions. At attained age 60, the ERRs per Gy for lung cancer were 7.1 for males and 15 for females; the averaged-attained age ERRs for liver cancer were 2.6 and 29 for males and females, respectively; those for bone cancer were 0.76 and 3.4. This study is the first to present and compare dose-response analyses for cancers of all 3 organs. The unique Mayak cohort with its high exposures and well characterized doses has allowed quantification of the plutonium dose-response for lung, liver and bone cancer risks based on direct human data. These results will play an important role in plutonium risk assessment.

Purpose The aim of this study is to quantify excess absolute risk (EAR) and excess relative risk (ERR) of secondary leukemia among a large population-based group of testicular cancer survivors. Methods We identified 42,722 1-year survivors of testicular cancer within 14 population-based cancer registries in Europe and North America (1943-2002). Poisson regression analysis was used to model EAR (per 100,000 person-years [PY]) and ERR of secondary leukemia. Cumulative risks were calculated using a competing risk model. Results Secondary leukemia developed in 89 patients (EAR = 10.8 per 100,000 PY, 95% confidence interval [CI] = 7.6-14.6; ERR = 1.6, 95%CI = 1.0-2.2). Statistically significantly elevated risks were observed for acute myeloid leukemia (AML) (EAR = 7.2, 95%CI = 4.7-10.2) and acute lymphoblastic leukemia (EAR = 1.3, 95%CI = 0.4-2.8). In multivariate analyses, AML risk was higher among patients whose initial management included chemotherapy compared to those receiving radiotherapy alone (p = 0.1). Excess cumulative leukemia risk was approximately 0.23% by 30 years after testicular cancer diagnosis. Conclusions Although ERR of leukemia following testicular cancer is large, EAR and cumulative risk, which are better gauges of the population burden, are small.

Purpose Hodgkin's lymphoma (HL) survivors are known to be at substantially increased risk of solid cancers (SC). However, no investigation has used multivariate modeling to estimate the relative risk (RR), excess absolute risk (EAR), and cumulative incidence for specific attained ages and ages at HL diagnosis. Patients and Methods We identified 18,862 5-year HL survivors from 13 population-based cancer registries in North America and Europe. Poisson regression was used to evaluate the effects of age at diagnosis, attained age, latency, sex, treatment, and year of diagnosis on the RR and EAR of SC. Results Among 1,490 identified SC, 850 were estimated to be in excess. For most cancer sites, both RR and EAR decreased with age at HL diagnosis and showed strong dependencies on attained age. For a patient diagnosed at age 30 years and survived to ≥ 40 years, modeled risks were significantly elevated for cancers of the breast (RR = 6.1), other supradiaphragmatic sites (RR = 6.0), and infradiaphragmatic sites (RR = 3.7); the largest RR (20-fold) was observed for malignant mesothelioma. Thirty-year cumulative risks of SC for men and women diagnosed at 30 years were 18% and 26%, respectively, compared with 7% and 9%, respectively, in the general population. For young HL patients, risks of breast and colorectal cancers were elevated 10 to 25 years before the age when routine screening would be recommended in the general population. Conclusion Multivariable modeling demonstrates for the first time temporal changes in SC risk not evident in unadjusted analyses, and can facilitate the development of individualized risk assessment and the creation of screening strategies for early detection.

To provide direct estimates of cancer risk after low-dose protracted exposure to ionizing radiation, a large-scale epidemiological study of nuclear industry workers was conducted in 15 countries. As part of this study, identification and quantification of errors in historical recorded doses was conducted based on a review of dosimetric practices and technologies in participating facilities. The main sources of errors on doses from "high-energy" photons (100-3000 keV) were identified as the response of dosimeters in workplace exposure conditions and historical calibration practices. Errors related to dosimetry technology and radiation fields were quantified to derive period- and facility-specific estimates of bias and uncertainties in recorded doses. This was based on (1) an evaluation of predominant workplace radiation from measurement studies and dosimetry expert assessment and (2) an estimation of the energy and geometry response of dosimeters used historically in study facilities. Coefficients were derived to convert recorded doses to H(p) (10) and organ dose, taking into account different aspects of the calibration procedures. A parametric, lognormal error structure model was developed to describe errors in doses as a function of facility and time period. Doses from other radiation types, particularly neutrons and radionuclide intake, could not be adequately reconstructed in the framework of the 15-Country Study. Workers with substantial doses from these radiation types were therefore identified and excluded from analyses. Doses from "lower-energy" photons (100 keV) and from "higher-energy" photons (3 MeV) were estimated to be small.

Radiation effects on mortality from solid cancers other than lung, liver, and bone cancer in the Mayak worker cohort: 1948–2008. The cohort of Mayak Production Association (PA) workers in Russia offers a unique opportunity to study the effects of prolonged low dose rate external gamma exposures and exposure to plutonium in a working age population. We examined radiation effects on the risk of mortality from solid cancers excluding sites of primary plutonium deposition (lung, liver, and bone surface) among 25,757 workers who were first employed in 1948–1982. During the period 1948–2008, there were 1,825 deaths from cancers other than lung, liver and bone. Using colon dose as a representative external dose, a linear dose response model described the data well. The excess relative risk per Gray for external gamma exposure was 0.16 (95% CI: 0.07 – 0.26) when unadjusted for plutonium exposure and 0.12 (95% CI 0.03 – 0.21) when adjusted for plutonium dose and monitoring status. There was no significant effect modification by sex or attained age. Plutonium exposure was not significantly associated with the group of cancers analyzed after adjusting for monitoring status. Site-specific risks were uncertainly estimated but positive for 13 of the 15 sites evaluated with a statistically significant estimate only for esophageal cancer. Comparison with estimates based on the acute exposures in atomic bomb survivors suggests that the excess relative risk per Gray for prolonged external exposure in Mayak workers may be lower than that for acute exposure but, given the uncertainties, the possibility of equal effects cannot be dismissed.

Schafer, D. W. and Gilbert, E. S. Some Statistical Implications of Dose Uncertainty in Radiation Dose–Response Analyses. Radiat. Res. 166, 303–312 (2006). Statistical dose–response analyses in radiation epidemiology can produce misleading results if they fail to account for radiation dose uncertainties. While dosimetries may differ substantially depending on the ways in which the subjects were exposed, the statistical problems typically involve a predominantly linear dose–response curve, multiple sources of uncertainty, and uncertainty magnitudes that are best characterized as proportional rather than additive. We discuss some basic statistical issues in this setting, including the bias and shape distortion induced by classical and Berkson uncertainties, the effect of uncertain dose-prediction model parameters on estimated dose–response curves, and some notes on statistical methods for dose–response estimation in the presence of radiation dose uncertainties.

Epidemiological studies of nuclear workers are an important source of direct information on the health effects of exposure to radiation at low doses and low dose rates. These studies have the important advantage of doses that have been measured objectively through the use of personal dosimeters. However, to make valid comparisons of worker-based estimates with those obtained from data on A-bomb survivors or persons exposed for medical reasons, attention must be given to potential biases and uncertainties in dose estimates. This paper discusses sources of error in worker dose estimates and describes efforts that have been made to quantify these errors. Of particular importance is the extensive study of errors in dosimetry that was conducted as part of a large collaborative study of nuclear workers in 15 countries being coordinated by the International Agency for Research on Cancer. The study, which focused on workers whose dose was primarily from penetrating gamma radiation in the range 100 keV to 3 MeV, included (1) obtaining information on dosimetry practices and radiation characteristics through the use of questionnaires; (2) two detailed studies of exposure conditions, one of nuclear power plants and the other of mixed activity facilities; and (3) a study of dosimeter response characteristics that included laboratory testing of 10 dosimeter designs commonly used historically. Based on these efforts, facility- and calendar year-specific adjustment factors have been developed, which will allow risks to be expressed as functions of organ doses with reasonable confidence.

Many women develop breast cancer after treatment for Hodgkin lymphoma (HL) at a young age. We estimated this future risk, taking into account age and calendar year of HL diagnosis, HL treatment information, population breast cancer incidence rates, and competing causes of death.Relative risks of breast cancer for categories defined by radiation dose to the chest (0, 20-40 Gy, oror = 40 Gy) and use of alkylating agents (yes or no) were estimated from a case-control study conducted within an international population-based cohort of 3817 female 1-year survivors of HL diagnosed at age 30 years or younger from January 1, 1965, through December 31, 1994. To compute cumulative absolute risks of breast cancer, we used modified standardized incidence ratios to relate cohort breast cancer risks to those in the general population, enabling application of population-based breast cancer rates, and we allowed for competing risks by using population-based mortality rates in female HL survivors.Cumulative absolute risks of breast cancer increased with age at end of follow-up, time since HL diagnosis, and radiation dose. For an HL survivor who was treated at age 25 years with a chest radiation dose of at least 40 Gy without alkylating agents, estimated cumulative absolute risks of breast cancer by age 35, 45, and 55 years were 1.4% (95% confidence interval [CI] = 0.9% to 2.1%), 11.1% (95% CI = 7.4% to 16.3%), and 29.0% (95% CI = 20.2% to 40.1%), respectively. Cumulative absolute risks were lower in women treated with alkylating agents.Breast cancer projections varied considerably by type of HL therapy, time since HL diagnosis, and age at end of follow-up. These estimates are applicable to HL survivors treated with regimens of the past and can be used to counsel such patients and plan management and preventive strategies. Projections should be used with caution, however, in patients treated with more recent approaches, including limited-field radiotherapy and/or ovary-sparing chemotherapy.

At present, direct data on risk from protracted or fractionated radiation exposure at low dose rates have been limited largely to studies of populations exposed to low cumulative doses with resulting low statistical power. We evaluated the cancer risks associated with protracted exposure to external whole-body gamma radiation at high cumulative doses (the average dose is 0.8 Gy and the highest doses exceed 10 Gy) in Russian nuclear workers. Cancer deaths in a cohort of about 21,500 nuclear workers who began working at the Mayak complex between 1948 and 1972 were ascertained from death certificates and autopsy reports with follow-up through December 1997. Excess relative risk models were used to estimate solid cancer and leukemia risks associated with external gamma-radiation dose with adjustment for effects of plutonium exposures. Both solid cancer and leukemia death rates increased significantly with increasing gamma-ray dose (P0.001). Under a linear dose-response model, the excess relative risk for lung, liver and skeletal cancers as a group (668 deaths) adjusted for plutonium exposure is 0.30 per gray (P0.001) and 0.08 per gray (P0.001) for all other solid cancers (1062 deaths). The solid cancer dose-response functions appear to be nonlinear, with the excess risk estimates at doses of less than 3 Gy being about twice those predicted by the linear model. Plutonium exposure was associated with increased risks both for lung, liver and skeletal cancers (the sites of primary plutonium deposition) and for other solid cancers as a group. A significant dose response, with no indication of plutonium exposure effects, was found for leukemia. Excess risks for leukemia exhibited a significant dependence on the time since the dose was received. For doses received within 3 to 5 years of death the excess relative risk per gray was estimated to be about 7 (P0.001), but this risk was only 0.45 (P = 0.02) for doses received 5 to 45 years prior to death. External gamma-ray exposures significantly increased risks of both solid cancers and leukemia in this large cohort of men and women with occupational radiation exposures. Risks at doses of less than 1 Gy may be slightly lower than those seen for doses arising from acute exposures in the atomic bomb survivors. As dose estimates for the Mayak workers are improved, it should be possible to obtain more precise estimates of solid cancer and leukemia risks from protracted external radiation exposure in this cohort.

ContextSecond cancer is the leading cause of death in long-term survivors of Hodgkin disease (HD), with exceptionally high risks of breast cancer among women treated at a young age. Quantitative associations between radiotherapy dose delivered to the breast and administered chemotherapy have not been reported to date in large series, nor has the influence of ovarian exposures on subsequent risk.ObjectiveTo quantify the long-term risk of breast cancer associated with use of radiotherapy and chemotherapy to treat young women with HD.Design, Setting, and SubjectsMatched case-control study of breast cancer within a cohort of 3817 female 1-year survivors of HD diagnosed at age 30 years or younger, between January 1, 1965, and December 31, 1994, and within 6 population-based cancer registries. The study was conducted March 1, 1996, through September 30, 1998.Main Outcome MeasuresRelative risk (RR) of breast cancer associated with radiation dose delivered to site of breast cancer or to ovaries and with cumulative dose of alkylating agents.ResultsBreast cancer occurred in 105 patients with HD who were matched to 266 patients with HD but without breast cancer. A radiation dose of 4 Gy or more delivered to the breast was associated with a 3.2-fold (95% confidence interval [CI], 1.4-8.2) increased risk, compared with the risk in patients who received lower doses and no alkylating agents. Risk increased to 8-fold (95% CI, 2.6-26.4) with a dose of more than 40 Gy (P

Aspects of radiation-induced lung cancer were evaluated in an international study of Hodgkin's disease. The study population consisted of 227 patients with lung cancer and 455 matched controls. Unique features included dose determinations to the specific location in the lung where each cancer developed and quantitative data on both chemotherapy and tobacco use obtained from medical records. The estimated excess relative risk (ERR) per Gy was 0.15 (95% CI: 0.06-0.39), and there was little evidence of departure from linearity even though lung doses for the majority of Hodgkin's disease patients treated with radiotherapy exceeded 30 Gy. The interaction of radiation and chemotherapy that included alkylating agents was almost exactly additive, and a multiplicative relationship could be rejected (P = 0.017). Conversely, the interaction of radiation and smoking was consistent with a multiplicative relationship, but not with an additive relationship (P < 0.001). The ERR/Gy for males was about four times that for females, although the difference was not statistically significant. There was little evidence of modification of the ERR/Gy by time since exposure (after a 5-year minimum latent period), age at exposure, or attained age. Because of the very high radiation doses received by Hodgkin's disease patients and the immunodeficiency inherent to this lymphoma and that associated with chemotherapy, generalizing these findings to other populations receiving considerably lower doses of radiation should be done cautiously.

This paper primarily discusses health effects that have resulted from exposures received as a result of above-ground nuclear tests, with emphasis on thyroid disease from exposure to 131I and leukemia and solid cancers from low dose rate external and internal exposure. Results of epidemiological studies of fallout exposures in the Marshall Islands and from the Nevada Test Site are summarized, and studies of persons with exposures similar to those from fallout are briefly reviewed (including patients exposed to 131I for medical reasons and workers exposed externally at low doses and low dose rates). Promising new studies of populations exposed in countries of the former Soviet Union are also discussed and include persons living near the Semipalatinsk Test Site in Kazakhstan, persons exposed as a result of the Chernobyl accident, and persons exposed as a result of operations of the Mayak Nuclear Plant in the Russian Federation. Very preliminary estimates of cancer risks from fallout doses received by the United States population are presented.

Benzene exposure has been causally linked with acute myeloid leukemia (AML), but inconsistently associated with other hematopoietic, lymphoproliferative and related disorders (HLD) or solid tumors in humans. Many neoplasms have been described in experimental animals exposed to benzene. We used Poisson regression to estimate adjusted relative risks (RR) and the likelihood ratio statistic to derive confidence intervals for cause-specific mortality and HLD incidence in 73,789 benzene-exposed compared with 34,504 unexposed workers in a retrospective cohort study in 12 cities in China. Follow-up and outcome assessment was based on factory, medical and other records. Benzene-exposed workers experienced increased risks for all-cause mortality (RR = 1.1, 95% CI = 1.1, 1.2) due to excesses of all neoplasms (RR = 1.3, 95% CI = 1.2, 1.4), respiratory diseases (RR = 1.7, 95% CI = 1.2, 2.3) and diseases of blood forming organs (RR = ∞, 95% CI = 3.4, ∞). Lung cancer mortality was significantly elevated (RR = 1.5, 95% CI = 1.2, 1.9) with similar RRs for males and females, based on three-fold more cases than in our previous follow-up. Significantly elevated incidence of all myeloid disorders reflected excesses of myelodysplastic syndrome/acute myeloid leukemia (RR = 2.7, 95% CI = 1.2, 6.6) and chronic myeloid leukemia (RR = 2.5, 95% CI = 0.8, 11), and increases of all lymphoid disorders included excesses of non-Hodgkin lymphoma (RR = 3.9, 95%CI = 1.5, 13) and all lymphoid leukemia (RR = 5.4, 95%CI = 1.0, 99). The 28-year follow-up of Chinese benzene-exposed workers demonstrated increased risks of a broad range of myeloid and lymphoid neoplasms, lung cancer, and respiratory diseases and suggested possible associations with other malignant and non-malignant disorders.

Background: Abdominal radiotherapy for testicular cancer (TC) increases risk for second stomach cancer, although data on the radiation dose–response relationship are sparse. Methods: In a cohort of 22 269 5-year TC survivors diagnosed during 1959–1987, doses to stomach subsites were estimated for 92 patients who developed stomach cancer and 180 matched controls. Chemotherapy details were recorded. Odds ratios (ORs) were estimated using logistic regression. Results: Cumulative incidence of second primary stomach cancer was 1.45% at 30 years after TC diagnosis. The TC survivors who received radiotherapy (87 (95%) cases, 151 (84%) controls) had a 5.9-fold (95% confidence interval (CI) 1.7–20.7) increased risk of stomach cancer. Risk increased with increasing stomach dose (P-trend

Received for publication April 27, 2001, and accepted for publica-tion August 29, 2001.Abbreviations: ALARA, as low as reasonably achievable; BEIR,Biological Effects of Ionizing Radiation; ICRP, InternationalCommission on Radiation Protection; NCRP, National Council onRadiation Protection and Measurements; UNSCEAR, UnitedNations Scientific Committee on the Effects of Atomic Radiation.

Background: Men with testicular cancer are at an increased risk of leukemia, but the relationship to prior treatments is not well characterized. The purpose of our study was to describe the risk of leukemia following radiotherapy and chemotherapy for testicular cancer. Methods: Within a population-based cohort of 18 567 patients diagnosed with testicular cancer (from 1970 through 1993), a case-control study of leukemia was undertaken, Radiation dose to active bone marrow and type and cumulative amount of cytotoxic drugs were compared between 36 men who developed leukemia and 106 matched control patients without leukemia. Conditional logistic regression was used to estimate the relative risk of leukemia associated with specific treatments. All P values are two-sided. Results: Radiotherapy (mean dose to active bone marrow, 12.6 Gy) without chemotherapy was associated with a threefold elevated risk of leukemia. Risk increased with increasing dose of radiation to active bone marrow (P for trend = .02), with patients receiving radiotherapy to the chest as well as to the abdominal/pelvic fields accounting for much of the risk at higher doses. Radiation dose to active bone marrow and the cumulative dose of cisplatin (P for trend = .001) were both predictive of excess leukemia risk in a model adjusted for all treatment variables. The estimated relative risk of leukemia at a cumulative dose of 650 mg cisplatin, which is commonly administered in current testicular cancer treatment regimens, was 3.2 (95% confidence interval = 1.5-8.4); larger doses (1000 mg) were linked with statistically significant sixfold increased risks. Conclusions: Past treatments for testicular cancer are associated with an increased risk of leukemia, with evidence for dose-response relationships for both radiotherapy and cisplatin-based chemotherapy. Statistically nonsignificant excesses are estimated for current radiotherapy regimens limited to the abdomen and pelvis: Among 10 000 patients given a treatment dose of 25 Gy and followed for 15 years, an excess of nine leukemias is predicted; cisplatin-based chemotherapy (dose, 650 mg) might result in 16 cases of leukemia. The survival advantage provided by current radiotherapy and chemotherapy regimens for testicular cancer far exceeds the small absolute risk of leukemia.

This paper discusses approaches for accounting for errors in dose estimates used in dose-response analyses of data from epidemiologic studies of workers exposed to external radiation and illustrates these approaches with analyses of data on workers at the Hanford site. In these analyses, estimates of the excess relative risk are corrected for bias in recorded doses as estimates of organ dose, and confidence intervals reflect uncertainty in the correction factors. For the Hanford data, these procedures did not greatly modify results for all cancer excluding leukemia, but the upper confidence limit for leukemia was increased by about 40%, a difference that is of some importance in comparing worker-based estimates and confidence intervals with estimates that serve as the basis of radiation protection standards. It is argued that aside from taking account of uncertainty in correction factors, no additional corrections are needed to address random errors resulting from variation in exposure energies and geometries. In addition, it is shown that because the larger cumulative doses, which are most influential in dose-response analyses, are the sums of large numbers of independent dosimeter readings, random errors resulting from variation in laboratory measurements are unlikely to be important for epidemiologic purposes. It is hoped that the approaches illustrated in this paper will be applied to future analyses of data from worker studies, especially combined analyses of data from several countries. Taking account of uncertainty in factors that correct for systematic bias will be especially important as uncertainty resulting from sampling variation decreases.

Therapy-related acute myeloid leukemia (tAML) is a rare but highly fatal complication of cytotoxic chemotherapy. Despite major changes in cancer treatment, data describing tAML risks over time are sparse. Among 426 068 adults initially treated with chemotherapy for first primary malignancy (9 US population-based cancer registries, 1975-2008), we identified 801 tAML cases, 4.70 times more than expected in the general population (P < .001). Over time, tAML risks increased after chemotherapy for non-Hodgkin lymphoma (n = 158; Poisson regression Ptrend < .001), declined for ovarian cancer (n = 72; Ptrend < .001), myeloma (n = 62; Ptrend = .02), and possibly lung cancer (n = 65; Ptrend = .18), and were significantly heterogeneous for breast cancer (n = 223; Phomogeneity = .005) and Hodgkin lymphoma (n = 58; Phomogeneity = .007). tAML risks varied significantly by age at first cancer and latency and were nonsignificantly heightened with radiotherapy for lung, breast, and ovarian cancers. We identified newly emerging elevated tAML risks in patients treated with chemotherapy since 2000 for esophageal, cervical, prostate, and possibly anal cancers; and since the 1990s for bone/joint and endometrial cancers. Using long-term, population-based data, we observed significant variation in tAML risk with time, consistent with changing treatment practices and differential leukemogenicity of specific therapies. tAML risks should be weighed against the benefits of chemotherapy, particularly for new agents and new indications for standard agents.

This paper describes an approach to quantifying errors in recorded estimates of external radiation dose obtained from personal dosimeters and applies the approach to dose estimates of workers at the Hanford site. Because a major objective of this evaluation is to provide the information needed for adjusting epidemiologic dose-response analyses of worker data for errors in dose estimates, the paper addresses the extent that errors for different workers are correlated, focuses on recorded doses as estimates of organ doses, and focuses on recorded doses as estimates of organ doses, and gives consideration to both annual and cumulative doses. The evaluation emphasizes errors resulting from the fact that dosimeters are limited in their ability to respond accurately to all radiation energies to which workers are exposed or to radiation coming from all directions. For each of several sources of error, systematic bias factors are estimated for two energy ranges (100--300 keV and 300--1,000 keV), two geometries (anterior-posterior and rotational), and four calendar year periods. These are then combined using information provided by health physicists on energies and geometries in Hanford exposure environments. Except for the period before 1958, deep dose, the objective of modern dosimetry systems, was found to be fairly accurately estimated. Lung dose was found to be overestimated by about 10%, and bone marrow dose was found to be overestimated by about 50%. However, many aspects of this evaluation relied heavily on subjective judgments, and, thus, these factors are subject to considerable uncertainty. Estimates of uncertainty in the bias factors and uncertainty reflecting random error are provided.

Although dose estimates used in epidemiologic studies of nuclear workers are far superior to exposure measures used in many epidemiologic studies, they are subject to several types of bias. These include bias resulting from practices used to measure and record very low doses and from underestimation of dose from neutrons. They also include bias resulting because available dose estimates do not include dose from internally deposited radionuclides, occupational dose received after workers have terminated employment at the facility of interest, or dose from background or medical exposures. These biases can potentially distort dose-response analyses and lead to biased risk estimates and confidence limits. This paper uses data on workers at the Hanford site to investigate the possible effects of these biases on dose-response analyses of leukemia and of all cancer except leukemia. This is accomplished by conducting analyses based on a variety of assumptions regarding the nature and magnitude of these biases. Results were not modified greatly (as compared to those based on the dose as recorded) for any of the 40 sensitivity analyses presented, including some based on fairly extreme assumptions. However, analyses that excluded workers with potential for dose from internal depositions and from neutrons did increase both the risk estimate and upper confidence limits; it may be desirable to emphasize this approach in future presentations. It is recommended that similar sensitivity analyses be performed with data from other worker studies, addressing the specific dosimetry problems that have been identified in those populations.

Rapid innovations in radiation therapy techniques have resulted in an urgent need for risk projection models for second cancer risks from high-dose radiation exposure, because direct observation of the late effects of newer treatments will require patient follow-up for a decade or more. However, the patterns of cancer risk after fractionated high-dose radiation are much less well understood than those after lower-dose exposures (0.1-5 Gy). In particular, there is uncertainty about the shape of the dose-response curve at high doses and about the magnitude of the second cancer risk per unit dose. We reviewed the available evidence from epidemiologic studies of second solid cancers in organs that received high-dose exposure (>5 Gy) from radiation therapy where dose-response curves were estimated from individual organ-specific doses. We included 28 eligible studies with 3434 second cancer patients across 11 second solid cancers. Overall, there was little evidence that the dose-response curve was nonlinear in the direction of a downturn in risk, even at organ doses of ≥60 Gy. Thyroid cancer was the only exception, with evidence of a downturn after 20 Gy. Generally the excess relative risk per Gray, taking account of age and sex, was 5 to 10 times lower than the risk from acute exposures of

Purpose To assess the dose–response relationship for stomach cancer after radiation therapy for cervical cancer. Methods and Materials We conducted a nested, matched case–control study of 201 cases and 378 controls among 53,547 5-year survivors of cervical cancer diagnosed from 1943 to 1995, from 5 international, population-based cancer registries. We estimated individual radiation doses to the site of the stomach cancer for all cases and to corresponding sites for the matched controls (overall mean stomach tumor dose, 2.56 Gy, range 0.03-46.1 and after parallel opposed pelvic fields, 1.63 Gy, range 0.12-6.3). Results More than 90% of women received radiation therapy, mostly with external beam therapy in combination with brachytherapy. Stomach cancer risk was nonsignificantly increased (odds ratio 1.27-2.28) for women receiving between 0.5 and 4.9 Gy to the stomach cancer site and significantly increased at doses ≥5 Gy (odds ratio 4.20, 95% confidence interval 1.41-13.4, P trend =.047) compared with nonirradiated women. A highly significant radiation dose–response relationship was evident when analyses were restricted to the 131 cases (251 controls) whose stomach cancer was located in the middle and lower portions of the stomach ( P trend =.003), whereas there was no indication of increasing risk with increasing dose for 30 cases (57 controls) whose cancer was located in the upper stomach ( P trend =.23). Conclusions Our findings show for the first time a significant linear dose–response relationship for risk of stomach cancer in long-term survivors of cervical cancer.

Little is known about long-term cancer risks following in utero radiation exposure. We evaluated the association between in utero radiation exposure and risk of solid cancer and leukemia mortality among 8,000 offspring, born from 1948–1988, of female workers at the Mayak Nuclear Facility in Ozyorsk, Russia. Mother’s cumulative gamma radiation uterine dose during pregnancy served as a surrogate for fetal dose. We used Poisson regression methods to estimate relative risks (RRs) and 95% confidence intervals (CIs) of solid cancer and leukemia mortality associated with in utero radiation exposure and to quantify excess relative risks (ERRs) as a function of dose. Using currently available dosimetry information, 3,226 (40%) offspring were exposed in utero (mean dose = 54.5 mGy). Based on 75 deaths from solid cancers (28 exposed) and 12 (6 exposed) deaths from leukemia, in utero exposure status was not significantly associated with solid cancer: RR = 0.94, 95% CI 0.58 to 1.49; ERR/Gy = −0.1 (95% CI < −0.1 to 4.1), or leukemia mortality; RR = 1.65, 95% CI 0.52 to 5.27; ERR/Gy = −0.8 (95% CI < −0.8 to 46.9). These initial results provide no evidence that low-dose gamma in utero radiation exposure increases solid cancer or leukemia mortality risk, but the data are not inconsistent with such an increase. As the offspring cohort is relatively young, subsequent analyses based on larger case numbers are expected to provide more precise estimates of adult cancer mortality risk following in utero exposure to ionizing radiation.

Background: Radiotherapy for breast cancer may expose the esophagus to ionizing radiation, but no study has evaluated esophageal cancer risk after breast cancer associated with radiation dose or systemic therapy use. Design: Nested case–control study of esophageal cancer among 289 748 ≥5-year survivors of female breast cancer from five population-based cancer registries (252 cases, 488 individually matched controls), with individualized radiation dosimetry and information abstracted from medical records. Results: The largest contributors to esophageal radiation exposure were supraclavicular and internal mammary chain treatments. Esophageal cancer risk increased with increasing radiation dose to the esophageal tumor location (Ptrend< 0.001), with doses of ≥35 Gy associated with an odds ratio (OR) of 8.3 [95% confidence interval (CI) 2.7–28]. Patients with hormonal therapy ≤5 years preceding esophageal cancer diagnosis had lower risk (OR = 0.4, 95% CI 0.2–0.8). Based on few cases, alkylating agent chemotherapy did not appear to affect risk. Our data were consistent with a multiplicative effect of radiation and other esophageal cancer risk factors (e.g. smoking). Conclusions: Esophageal cancer is a radiation dose-related complication of radiotherapy for breast cancer, but absolute risk is low. At higher esophageal doses, the risk warrants consideration in radiotherapy risk assessment and long-term follow-up.

Radiation exposure, particularly at a young age, is an established cause of breast cancer. It is not known whether radiation-related breast cancer risk varies by molecular subtype. We characterized the relative risk (RR) of contralateral breast cancer (CBC) related to radiotherapy by histology and estrogen receptor (ER) status of the CBC in five-year survivors in the Surveillance, Epidemiology, and End Results database using Poisson regression models adjusted for attained age and calendar year, age at and year of treatment, ER status of the first breast cancer, and disease stage. 205,316 female breast cancer survivors were followed for an average of 10 years from 1973 until 2007, during which time 6924 women developed a subsequent primary invasive breast cancer in the contralateral breast. The overall RR (and 95% confidence interval (CI)) of radiotherapy-related CBC was 1.11 (1.05-1.16). There was no heterogeneity in risk according to histology of the CBC (P 0.50) for all ages or young age at exposure, but case numbers were small for subtypes other than ductal and lobular carcinomas. Information on ER status was available from 1990 onwards for 3546 CBC cases, of which 2597 (73%) were ER+ and 949 (27%) were ER-. The RRs were 1.10 (1.02-1.19) for ER+ CBC and 1.19 (1.04-1.35) for ER- CBC (P (difference) = 0.33). Among women treated age 35 years, radiation-related risk of CBC was non-significantly elevated for ER- (RR = 1.38, 95% CI: 0.96-1.97) but not for ER+ tumors (RR = 0.80, 95% CI: 0.47-1.35) (P (difference) = 0.09). We did not find clear evidence that radiation-related risk varies by histology or ER status, but our findings, which were the first to examine this question, were suggestive of possible differences by ER status that may merit further investigation.