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Abstract Background An important public health goal is to decrease the prevalence of key behavioural risk factors, such as tobacco use and obesity. Survey information is often available at the regional level, but heterogeneity within large geographic regions cannot be assessed. Advanced spatial analysis techniques are demonstrated to produce sensible micro area estimates of behavioural risk factors that enable identification of areas with high prevalence. Methods A spatial Bayesian hierarchical model was used to estimate the micro area prevalence of current smoking and excess bodyweight for the Erie-St. Clair region in southwestern Ontario. Estimates were mapped for male and female respondents of five cycles of the Canadian Community Health Survey (CCHS). The micro areas were 2006 Census Dissemination Areas, with an average population of 400–700 people. Two individual-level models were specified: one controlled for survey cycle and age group (model 1), and one controlled for survey cycle, age group and micro area median household income (model 2). Post-stratification was used to derive micro area behavioural risk factor estimates weighted to the population structure. SaTScan analyses were conducted on the granular, postal-code level CCHS data to corroborate findings of elevated prevalence. Results Current smoking was elevated in two urban areas for both sexes (Sarnia and Windsor), and an additional small community (Chatham) for males only. Areas of excess bodyweight were prevalent in an urban core (Windsor) among males, but not females. Precision of the posterior post-stratified current smoking estimates was improved in model 2, as indicated by narrower credible intervals and a lower coefficient of variation. For excess bodyweight, both models had similar precision. Aggregation of the micro area estimates to CCHS design-based estimates validated the findings. Conclusions This is among the first studies to apply a full Bayesian model to complex sample survey data to identify micro areas with variation in risk factor prevalence, accounting for spatial correlation and other covariates. Application of micro area analysis techniques helps define areas for public health planning, and may be informative to surveillance and research modeling of relevant chronic disease outcomes.

Background: An important public health goal is to decrease the prevalence of key behavioural risk factors, such as tobacco use and obesity. Survey information is often available at the regional level, but heterogeneity within large geographic regions cannot be assessed. Advanced spatial analysis techniques are demonstrated to produce sensible micro area estimates of behavioural risk factors that enable identification of areas with high prevalence., Methods: A spatial Bayesian hierarchical model was used to estimate the micro area prevalence of current smoking and excess bodyweight for the Erie-St. Clair region in southwestern Ontario. Estimates were mapped for male and female respondents of five cycles of the Canadian Community Health Survey (CCHS). The micro areas were 2006 Census Dissemination Areas, with an average population of 400-700 people. Two individual-level models were specified: one controlled for survey cycle and age group (model 1), and one controlled for survey cycle, age group and micro area median household income (model 2). Post-stratification was used to derive micro area behavioural risk factor estimates weighted to the population structure. SaTScan analyses were conducted on the granular, postal-code level CCHS data to corroborate findings of elevated prevalence., Results: Current smoking was elevated in two urban areas for both sexes (Sarnia and Windsor), and an additional small community (Chatham) for males only. Areas of excess bodyweight were prevalent in an urban core (Windsor) among males, but not females. Precision of the posterior post-stratified current smoking estimates was improved in model 2, as indicated by narrower credible intervals and a lower coefficient of variation. For excess bodyweight, both models had similar precision. Aggregation of the micro area estimates to CCHS design-based estimates validated the findings., Conclusions: This is among the first studies to apply a full Bayesian model to complex sample survey data to identify micro areas with variation in risk factor prevalence, accounting for spatial correlation and other covariates. Application of micro area analysis techniques helps define areas for public health planning, and may be informative to surveillance and research modeling of relevant chronic disease outcomes.

Introduction: Evidence suggests that current levels of tritium emissions from CANDU reactors in Canada are not related to adverse health effects. However, these studies lack tritium-specific dose data and have small numbers of cases. The purpose of our study was to determine whether tritium emitted from a nuclear-generating station during routine operation is associated with risk of cancer in Pickering, Ontario., Methods: A retrospective cohort was formed through linkage of Pickering and north Oshawa residents (1985) to incident cancer cases (1985-2005). We examined all sites combined, leukemia, lung, thyroid and childhood cancers (6-19 years) for males and females as well as female breast cancer. Tritium estimates were based on an atmospheric dispersion model, incorporating characteristics of annual tritium emissions and meteorology. Tritium concentration estimates were assigned to each cohort member based on exact location of residence. Person-years analysis was used to determine whether observed cancer cases were higher than expected. Cox proportional hazards regression was used to determine whether tritium was associated with radiation-sensitive cancers in Pickering., Results: Person-years analysis showed female childhood cancer cases to be significantly higher than expected (standardized incidence ratio [SIR] = 1.99, 95% confidence interval [CI]: 1.08-3.38). The issue of multiple comparisons is the most likely explanation for this finding. Cox models revealed that female lung cancer was significantly higher in Pickering versus north Oshawa (HR = 2.34, 95% CI: 1.23-4.46) and that tritium was not associated with increased risk. The improved methodology used in this study adds to our understanding of cancer risks associated with low-dose tritium exposure., Conclusion: Tritium estimates were not associated with increased risk of radiationsensitive cancers in Pickering.

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, Ptrend=.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 (Ptrend=.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 (Ptrend=.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., (Published by Elsevier Inc.)

Background: The role of social-environmental factors in physical activity (PA) within lower income and ethnic minority populations is understudied. This study explored correlates of age-related PA and perceived walkability (PW)., Methods: Cross-sectional data (N = 401 women; ≥18 y) were collected within the Jane-Finch community in Toronto, Ontario using questionnaires. Generalized additive models, an extension to multiple regression, were used to estimate effect sizes and standard errors., Results: Significant interactions between native language and car access (CA) were observed in PA variation across the lifespan. Individuals were evenly distributed across 4 comparison groups: 29.2% English-NoCA, 24.1% English-CA, 20.7% Non-English-NoCA, and 26.0% NonEnglish-CA. Risk of sedentariness increased with age for native English speakers > 50 years, but appears unaffected by age for other groups. English speakers without CA < 60 years appear least likely to be sedentary, followed by English speakers with CA. In general, an active individual at the 75th percentile of social support for exercise would have 1.62 (CI: 1.22-2.17) times the MET-Hours of PA than an active individual at the 25th percentile of SSE., Conclusions: English language facility and car access moderate relationships of social-environmental factors and PA. Further investigation is required to better understand correlates of PA for women in this demographic.

Objective: To develop a measure of cancer services integration (CSI) that can inform clinical and administrative decision-makers in their efforts to monitor and improve cancer system performance., Methods: We employed a systematic approach to measurement development, including review of existing cancer/health services integration measures, key-informant interviews and focus groups with cancer system leaders. The research team constructed a Web-based survey that was field- and pilot-tested, refined and then formally conducted on a sample of cancer care providers and administrators in Ontario, Canada. We then conducted exploratory factor analysis to identify key dimensions of CSI., Results: A total of 1,769 physicians, other clinicians and administrators participated in the survey, responding to a 67-item questionnaire. The exploratory factor analysis identified 12 factors that were linked to three broader dimensions: clinical, functional and vertical system integration., Conclusions: The CSI Survey provides important insights on a range of typically unmeasured aspects of the coordination and integration of cancer services, representing a new tool to inform performance improvement efforts.

Aims: To determine the utility of web-based radiation wait time information for patients and health care providers in decision-making. To revise the information using a simulated laboratory environment and to re-evaluate the new web-based information., Materials and Methods: An online 'pop-up' survey on the Cancer Care Ontario (CCO) website measured user satisfaction. Qualitative data were gathered through patient focus groups and physician interviews. On the basis of the analysis, the website was revised and usability testing conducted. The information was re-evaluated by end-users through survey methodology., Results: The majority accessing the wait time website were patients and family members. The modal age of use of the website was 31-50 years. Patients found the information more helpful after redesign than health professionals, but both found the language less easy to understand, highlighting the need to continuously evaluate the effectiveness of the website. Patients did not identify themselves as consumers of wait time information. Their expectation was that physicians would determine the urgency for treatment and would ensure timely access to care. Physicians reported that they did not use the CCO website on wait times and would not use the data for decision-making. Referrals were based on urgency of care and usual referral patterns. Referral patterns did not shift to centres with shorter wait times., Conclusions: The results of this study did not confirm the usefulness of the web-based wait time information for patients and physicians as a resource on how to obtain timely access to radiation treatment. Patients relied on their physician to manage their access to treatment according to the urgency of their clinical condition. Physicians preferred their established referral process rather than referring their patients to centres with shorter wait times. As patients become more computer savvy, it will be interesting to see if they increasingly become consumers of web-based wait time information.

Background: Internet survey modalities often compare unfavorably with traditional survey modalities, particularly with respect to response rates. Response to Internet surveys can be affected by the distribution options and response/collection features employed as well as the existence of automated (out-of-office) replies, automated forwarding, server rejection, and organizational or personal spam filters. However, Internet surveys also provide unparalleled opportunities to track study subjects and examine many of the factors influencing the determination of response rates. Tracking data available for Internet surveys provide detailed information and immediate feedback on a significant component of response that other survey modalities cannot match. This paper presents a response audit of a large Internet survey of more than 5000 cancer care providers and administrators in Ontario, Canada., Objective: Building upon the CHEcklist for Reporting Results of Internet E-Surveys (CHERRIES), the main objectives of the paper are to (a) assess the impact of a range of factors on the determination of response rates for Internet surveys and (b) recommend steps for improving published descriptions of Internet survey methods., Methods: We audited the survey response data, analyzing the factors that affected the numerator and denominator in the ultimate determination of response. We also conducted a sensitivity analysis to account for the inherent uncertainty associated with the impact of some of the factors on the response rates., Results: The survey was initially sent out to 5636 health care providers and administrators. The determination of the numerator was influenced by duplicate/unattached responses and response completeness. The numerator varied from a maximum of 2031 crude (unadjusted) responses to 1849 unique views, 1769 participants, and 1616 complete responses. The determination of the denominator was influenced by forwarding of the invitation email to unknown individuals, server rejections, automated replies, spam filters, and 'opt out' options. Based on these factors, the denominator varied from a minimum of 5106 to a maximum of 5922. Considering the different assumptions for the numerator and the denominator, the sensitivity analysis resulted in a 12.5% variation in the response rate (from minimum of 27.3% to maximum of 39.8%) with a best estimate of 32.8%., Conclusions: Depending on how the numerator and denominator are chosen, the resulting response rates can vary widely. The CHERRIES statement was an important advance in identifying key characteristics of Internet surveys that can influence response rates. This response audit suggests the need to further clarify some of these factors when reporting on Internet surveys for health care providers and administrators, particularly when using commercially available Internet survey packages for specified, rather than convenience, samples.

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.

Background and Objective: Methylating agents are effective chemotherapy agents for Hodgkin lymphoma, but are associated with the development of second primary cancers. Cytotoxicity of methylating agents is mediated primarily by the DNA mismatch repair (MMR) system. Loss of MLH1, a major component of DNA MMR, results in tolerance to the cytotoxic effects of methylating agents and persistence of mutagenised cells at high risk of malignant transformation. We hypothesised that a common substitution in the basal promoter of MLH1 (position -93, rs1800734) modifies the risk of cancer after methylating chemotherapy., Methods: 133 patients who developed cancer following chemotherapy and/or radiotherapy (n = 133), 420 patients diagnosed with de novo myeloid leukaemia, 242 patients diagnosed with primary Hodgkin lymphoma, and 1177 healthy controls were genotyped for the MLH1 -93 polymorphism by allelic discrimination polymerase chain reaction (PCR) and restriction fragment length polymorphism assay. Odds ratios and 95% confidence intervals for cancer risk by MLH1 -93 polymorphism status, and stratified by previous exposure to methylating chemotherapy, were calculated using unconditional logistic regression., Results: Carrier frequency of the MLH1 -93 variant was higher in patients who developed therapy related acute myeloid leukaemia (t-AML) (75.0%, n = 12) or breast cancer (53.3%. n = 15) after methylating chemotherapy for Hodgkin lymphoma compared to patients without previous methylating exposure (t-AML, 30.4%, n = 69; breast cancer patients, 27.2%, n = 22). The MLH1 -93 variant allele was also over-represented in t-AML cases when compared to de novo AML cases (36.9%, n = 420) and healthy controls (36.3%, n = 952), and was associated with a significantly increased risk of developing t-AML (odds ratio 5.31, 95% confidence interval 1.40 to 20.15), but only in patients previously treated with a methylating agent., Conclusions: These data support the hypothesis that the common polymorphism at position -93 in the core promoter of MLH1 defines a risk allele for the development of cancer after methylating chemotherapy for Hodgkin lymphoma. However, replication of this finding in larger studies is suggested.

Background: Although modern treatments for testicular cancer are associated with increased survival, the long-term health effects of these treatments are unclear. We conducted a population-based study to quantify the long-term risks of mortality from noncancer causes among men with testicular cancer., Methods: We identified 38,907 one-year survivors of testicular cancer within 14 population-based cancer registries in North America and Europe (from 1943 through 2002). We used data from these registries to calculate standardized mortality ratios (SMRs) for noncancer deaths and to evaluate associations between histology, age at testicular cancer diagnosis, calendar year of diagnosis, and initial treatment and the risk of noncancer mortality. All statistical tests were two-sided., Results: A total of 2942 deaths from all noncancer causes were reported after a median follow-up of 10 years, exceeding the expected number of deaths from all noncancer causes in the general population by 6% (SMR = 1.06, 95% confidence interval [CI] = 1.02 to 1.10); the noncancer standardized mortality ratios did not differ statistically significantly between patients diagnosed before and after 1975, when cisplatin-based chemotherapy came into widespread use. Compared with the general population, testicular cancer survivors had higher mortality from infections (SMR = 1.28, 95% CI = 1.12 to 1.47) and from digestive diseases (SMR = 1.44, 95% CI = 1.26 to 1.64). Mortality from all circulatory diseases was statistically significantly elevated in men diagnosed with testicular cancer before age 35 years (1.23, 95% CI = 1.09 to 1.39) but not in men diagnosed at older ages (SMR = 0.94; 95% CI = 0.89 to 1.00). Men treated with chemotherapy (with or without radiotherapy) in 1975 or later had higher mortality from all noncancer causes (SMR = 1.34, 95% CI = 1.15 to 1.55), all circulatory diseases (SMR = 1.58, 95% CI = 1.25 to 2.01), all infections (SMR = 2.48, 95% CI = 1.70 to 3.50), and all respiratory diseases (SMR = 2.53, 95% CI = 1.26 to 4.53). Testicular cancer patients who were younger than 35 years at diagnosis and were treated with radiotherapy alone in 1975 or later had higher mortality from all circulatory diseases (SMR = 1.70, 95% CI = 1.21 to 2.31) compared with the general population., Conclusion: Men who have survived for at least 1 year after being diagnosed with testicular cancer have a slightly higher risk of dying from noncancer causes, including infections, digestive diseases, and circulatory diseases, than the general population. Men treated with chemotherapy in 1975 or later may be at particularly high risk.

Background: There is a lack of information from Canadian hospitals on the role of hospital characteristics such as procedure volume and teaching status on the survival of patients who undergo major cancer resection. Therefore, we chose to study these relationships using data from patients treated in Ontario hospitals., Methods: We used the Ontario Cancer Registry from calendar years 1990-2000 to obtain data on patients who underwent surgery for breast, colon, lung or esophageal cancer or who underwent major liver surgery related to a cancer diagnosis between 1990 and 1995 in order to assess the influence of volume of procedures and teaching status of hospitals on in-hospital death rate and long-term survival. For each disease site and before observing patient outcomes data, volume cut-off points were selected to create volume groups with similar numbers of patients. Teaching hospitals were those directly affiliated with a medical school. Logistic regression and proportional hazards models were used to consider the clustering of data at the hospital level and to assess operative death and long-term survival. We also used 4 measures to gauge the degree of procedure regionalization across the province including (1) the number of hospitals performing a procedure; (2) the percentage of patients treated in teaching hospitals; (3) the percentage of rural patients treated in higher volume procedure hospitals; and (4) median distances travelled by patients to receive care., Results: The number of patients in our cohorts who underwent resection of the breast, colon, lung, esophagus or liver was 14 346, 8398, 2698, 629 and 362, respectively. Surgery in a high-volume versus a low-volume hospital did not have a statistically significant influence on the odds of operative death for patients who underwent colon, liver, lung or esophageal cancer resection. The risk of long-term death was increased in low-volume versus high-volume hospitals for patients who underwent resection of the breast (hazard ratio [HR] 1.2, 95% confidence interval [95% CI] 1.0-1.4, p < 0.05), lung (HR 1.3, 95% CI 1.1-1.6, p < 0.01) and liver (HR 1.7, 95% CI 1.0-2.7, p = 0.04). There were no significant differences in the odds of operative (in-hospital) death or risk of long-term death among patients treated in teaching compared with nonteaching hospitals. There was more regionalization of liver, lung and esophageal operations versus breast and colon operations., Conclusions: Increased hospital procedure volume correlated with improved longterm survival for patients in Ontario who underwent some, but not all, cancer resections, whereas hospital teaching status had no significant impact on patient outcomes. Across the province, further regionalization of care may help improve the quality of some cancer procedures.

Purpose: Two previous studies, by Gorey et al. and Boyd et al., compared associations between socioeconomic status (SES) and cancer survival in Canada and the United States. Both studies used SES information from population censuses linked to cancer registries. This study investigates why two similar studies led to apparently conflicting results., Methods: We conducted analyses following analytic details provided by the previously published studies to describe cancer survival in Toronto, Canada, and Detroit, MI. We examined the effects of choice of census indicators and census levels on the observed SES-related gradients in cancer survival., Results: Significant associations between SES and cancer survival were observed in Toronto for several major disease sites when median household income was used as an SES indicator. Associations were weaker when a poverty indicator was used. In Detroit, similar SES gradients were observed by using both income and poverty as SES indicators. When SES quintiles were represented by income ranks, SES-associated survival gradients were much steeper in Detroit than Toronto. When SES was described by the median income in each quintile, gradients were similar in the two cities., Conclusions: The apparent contradiction in results of two previous studies is related to the choice of SES indicators. Poverty may not be an indicator of choice for such an intercountry comparison.

Purpose: Urachal carcinoma accounts for less than 1% of all bladder cancers. Limited data exist on disease related outcomes originating from case reports and select referral centers. We describe a population based outcomes analysis with long-term followup in patients in the province of Ontario., Materials and Methods: We reviewed the data source of the Ontario Cancer Registry for patients diagnosed with urachal cancer during 1976 to 2001. A cohort of 40 patients with urachal adenocarcinoma was found. Primary outcome measures were overall and disease specific survival. The effect of patient age, sex, grade, stage and university vs nonacademic treating hospital as predictors of outcome was determined., Results: Median patient age was 52 years. Median followup was 72.7 months. Mean overall survival +/- SD was 121.6 +/- 21 months. Mean disease specific survival in patients treated operatively was 165 +/- 27 months with 5 and 10-year disease specific survival of 61.3% and 49.2%, respectively. Disease specific mortality was not evident after 7 years from diagnosis. Well differentiated tumors in a third of the patients were associated with a 90% cure rate when treated operatively. Well differentiated tumors, and noninvolvement of adjacent organs and the peritoneum correlated with better prognosis (p = 0.004, p = 0.03 and 0.045, respectively)., Conclusions: Urachal adenocarcinoma occurs in all age groups. Long-term disease specific survival can be achieved with partial cystectomy. Covariates associated with better disease specific survival are well differentiated tumor grade and the absence of adjacent organ or peritoneal involvement. No relapses were observed after 7 years.

Treatments for Hodgkin lymphoma are associated with large relative risks of acute myeloid leukemia (AML), but there are few estimates of the excess absolute risk (EAR), a useful measure of disease burden. One-year Hodgkin lymphoma survivors (N = 35,511) were identified within 14 population-based cancer registries in Nordic countries and North America from January 1, 1970, through December 31, 2001. We used Poisson regression analysis to model the EAR of AML, per 10,000 person-years. A total of 217 Hodgkin lymphoma survivors were diagnosed with AML (10.8 expected; unadjusted EAR = 6.2; 95% confidence interval = 5.4 to 7.1). Excess absolute risk for AML was highest during the first 10 years after Hodgkin lymphoma diagnosis but remained elevated thereafter. In subsequent analyses, adjusted for time since Hodgkin lymphoma diagnosis and presented for the 5-9 year interval, the EAR was statistically significantly (P < .001) larger in patients diagnosed with Hodgkin lymphoma at age 35 years and older than in those diagnosed before 35 years of age. The EAR of AML declined statistically significantly after 1984 (7.0 to 4.2 and 16.4 to 9.9 in the < 35 and > or = 35 age groups, respectively), which may be associated with modifications in chemotherapy.

Background and Objectives: The Ontario Cancer Registry (OCR) is a population-based tumor registry created to provide data for epidemiologic research and for cancer surveillance. Recently it has been used for health services research. The objective of this project was to assess the quality of the OCR data that is used in survival analysis., Methods and Design: Clinical information for 898 patients with squamous carcinoma of the head and neck including index tumor site, date of diagnosis, vital status, date of death, and cause of death from a prospective database at the Kingston Regional Cancer Center is compared to the same data elements in the OCR for the same patients., Results: There is no statistically significant difference in disease-specific survival between the information from the two databases (log rank P = .89). The OCR captured and correctly assigned index tumor site for 81.4% (detection rate). The site assignment was accurate 90.9% of the time (confirmation rate), there was agreement on vital status (dead vs. alive) for all but one patient, and there was excellent agreement on date of death. However, cause of death (cancer vs. noncancer) based on death certificates had a 31% error rate., Conclusion: Researchers can be confident in the survival analysis generated from data in this registry, but need to be aware of potential sources of error.

The importance of genetic and other risk factors in the development of breast cancer after radiotherapy (RT) for Hodgkin lymphoma (HL) has not been determined. We analyzed data from a breast cancer case-control study (105 patients, 266 control subjects) conducted among 3 817 survivors of HL diagnosed at age 30 years or younger in 6 population-based cancer registries. Odds ratios (ORs) and excess relative risks (ERRs) were calculated using conditional regression. Women who received RT exposure (> or = 5 Gy radiation dose to the breast) had a 2.7-fold increased breast cancer risk (95% confidence interval (CI) 1.4-5.2), compared with those given less than 5 Gy. RT exposure (> or = 5 Gy) was associated with an OR of 0.8 (95% CI, 0.2-3.4) among women with a first- or second-degree family history of breast or ovarian cancer, and 5.8 (95% CI, 2.1-16.3) among all other women (interaction P = .03). History of a live birth appeared to increase the breast cancer risk associated with RT among women not treated with ovarian-damaging therapies. Breast cancer risk following RT varied little according to other factors. The additional increased relative risk of breast cancer after RT for HL is unlikely to be larger among women with a family history of breast or ovarian cancer than among other women.

Background: Radical prostatectomy is associated with excellent long-term disease control for localized prostate cancer. Prior studies have suggested an increased risk of short-term complications among older men who underwent radical prostatectomy, but these studies did not adjust for comorbidity., Methods: We examined mortality and complications occurring within 30 days following radical prostatectomy among all 11,010 men who underwent this surgery in Ontario, Canada, between 1990 and 1999 using multivariable logistic regression modeling. We adjusted for comorbidity using two common comorbidity indices. Statistical tests were two-sided., Results: Overall, 53 men (0.5%) died, and 2195 [corrected] (19.9%[corrected]) had one or more complications within 30 days of radical prostatectomy. In models adjusted for comorbidity and year of surgery, age was associated with an increased risk of 30-day mortality (odds ratio = 2.04 per decade of age, 95% confidence interval [CI] = 1.23 to 3.39). However, the absolute 30-day mortality risk was low, even in older men, at 0.66% (95% CI = 0.2 to 1.1%) for men aged 70-79 years. In adjusted models, age was associated with an increased risk of cardiac (Ptrend < .001), respiratory (Ptrend = .01), and miscellaneous medical (Ptrend = .058) complications. Similarly, increasing comorbidity was associated with a higher risk of all categories of complications., Conclusions: Increasing comorbidity is a stronger predictor than age of almost all categories of early complications after radical prostatectomy. The risk of postoperative mortality after radical prostatectomy is relatively low for otherwise healthy older men up to age 79.

Background: 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., Methods: Relative risks of breast cancer for categories defined by radiation dose to the chest (0, 20- < 40 Gy, or > or = 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., Results: 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., Conclusions: 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.

Gastric cancer (GC) remains a leading cause of cancer mortality worldwide. Genetic factors are implicated, including DNA mismatch repair (MMR) deficiency manifested as tumor microsatellite instability (MSI). However, a standardized panel of markers and a definition of low-versus-high level MSI in GC are lacking. We examined a population-based cohort of early onset (or=3 markers MSI+/MSI-high) demonstrated MMR protein deficiency. Three novel hMLH1 mutations (two germline frameshift and one somatic nonsense) were also found. The only significant clinicopathological associations were increased tumor size in MSI+ cases (P=0.04) and Lauren histotype (P=0.006) and tumor grade (P=0.007) in MSI-high cases. Tumor size, location, depth, nodal status, and Ming subtype were significant prognostic variables. Therefore, we propose a new definition of high-level MSI based on unifying characteristics of instability of more than or equal to three of six mononucleotide markers and loss of MMR protein expression.

Background: Although second primary cancers are a leading cause of death among men with testicular cancer, few studies have quantified risks among long-term survivors., Methods: Within 14 population-based tumor registries in Europe and North America (1943-2001), we identified 40,576 1-year survivors of testicular cancer and ascertained data on any new incident solid tumors among these patients. We used Poisson regression analysis to model relative risks (RRs) and excess absolute risks (EARs) of second solid cancers. All statistical tests were two-sided., Results: A total of 2,285 second solid cancers were reported in the cohort. The relative risk and EAR decreased with increasing age at testicular cancer diagnosis (P < .001); the EAR increased with attained age (P < .001) but the excess RR decreased. Among 10-year survivors diagnosed with testicular cancer at age 35 years, the risk of developing a second solid tumor was increased (RR = 1.9, 95% confidence interval [CI] = 1.8 to 2.1). Risk remained statistically significantly elevated for 35 years (RR = 1.7, 95% CI = 1.5 to 2.0; P < .001). We observed statistically significantly elevated risks, for the first time, for cancers of the pleura (malignant mesothelioma; RR = 3.4, 95% CI = 1.7 to 5.9) and esophagus (RR = 1.7, 95% CI = 1.0 to 2.6). Cancers of the lung (RR = 1.5, 95% CI = 1.2 to 1.7), colon (RR = 2.0, 95% CI = 1.7 to 2.5), bladder (RR = 2.7, 95% CI = 2.2 to 3.1), pancreas (RR = 3.6, 95% CI = 2.8 to 4.6), and stomach (RR = 4.0, 95% CI = 3.2 to 4.8) accounted for almost 60% of the total excess. Overall patterns were similar for seminoma and nonseminoma patients, with lower risks observed for nonseminoma patients treated after 1975. Statistically significantly increased risks of solid cancers were observed among patients treated with radiotherapy alone (RR = 2.0, 95% CI = 1.9 to 2.2), chemotherapy alone (RR = 1.8, 95% CI = 1.3 to 2.5), and both (RR = 2.9, 95% CI = 1.9 to 4.2). For patients diagnosed with seminomas or nonseminomatous tumors at age 35 years, cumulative risks of solid cancer 40 years later (i.e., to age 75 years) were 36% and 31%, respectively, compared with 23% for the general population., Conclusions: Testicular cancer survivors are at statistically significantly increased risk of solid tumors for at least 35 years after treatment. Young patients may experience high levels of risk as they reach older ages. The statistically significantly increased risk of malignant mesothelioma in testicular cancer survivors has, to our knowledge, not been observed previously in a cohort of patients treated with radiotherapy.

Purpose: Older patients are underrepresented in many areas of cancer services utilization and in clinical trial enrollment. This study evaluates whether age, when adjusted for sex, comorbidity, stage, tumor site, geography, and time period, is predictive of cancer treatment practice., Methods: First, we used the Ontario Cancer Registry (OCR) to examine for any apparent differences in treatment practices between elderly (> or = 70 years) and younger patients in the last three decades. Second, we performed a chart review of 1,505 patients with lung, breast, and colorectal cancers seen in Ontario either at an urban center, the Princess Margaret Hospital, or at a rural center, the Northwestern Regional Cancer Centre. Patients were randomly selected from two time periods, 1977 to 1978 and 1997; and the study population was to comprise at least 50% elderly patients., Results: OCR data demonstrated that, in some settings, such as colorectal cancer, the proportions of elderly cancer patients who were referred to cancer centers and who received any cancer treatment were lower than their younger counterparts. The chart review data showed that increasing age was a significant negative predictor for receiving any cancer treatment (P < .001, multivariate analysis) and for having a clinical trial discussion with the treating specialist (P < .001, multivariate analysis)., Conclusion: Independent of other factors, older age is consistently a cause of disparity in cancer treatment practice and in clinical trial discussion with patients. By increasing the accrual rate of elderly cancer patients in clinical trials, a better understanding of appropriate therapies for this patient population can be obtained and may, thereby, impact on their cancer-related morbidity and mortality.

Purpose: To determine how long patients in Ontario waited for major breast, colorectal, lung or prostate cancer surgery in the years 1993-2000., Methods: "Surgical waiting time" was defined as the interval from date of preoperative surgeon consult to date of hospital admission for surgery. We created patient cohorts by linking appropriate diagnosis and procedure codes from Canadian Institutes of Health Information data. Scrambled unique surgeon identifiers were obtained from Ontario Health Insurance Plan data. Changes in median surgical waiting times were assessed with univariate time-trend analyses and multilevel models. Models were controlled for year of surgery and other patient (age, gender, comorbid conditions, income level, area of residence) and hospital level characteristics (teaching status, procedure volume status)., Results: Compared with 1993, median surgical waiting times in the year 2000 increased 36% for patients with breast cancer (to 19 d), 46% with colorectal (to 19 d), 36% with lung (to 34 d) and 4% with prostate cancer (to 83 d). Multilevel models confirmed significant increases in waiting times for all procedures. There were no concerning or consistent differences in waiting times among the categories of hospitals and patients examined., Discussion: There were significant increases in surgical waiting times among patients undergoing breast, colorectal, lung or prostate cancer surgery in Ontario over years 1993-2000. Administrative databases can be used to efficiently measure such waits.

Context: Second 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., Objective: To quantify the long-term risk of breast cancer associated with use of radiotherapy and chemotherapy to treat young women with HD., Design, Setting, and Subjects: Matched 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 Measures: Relative 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., Results: Breast 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<.001 for trend). Radiation risk did not vary appreciably by age at exposure or reproductive history. Increased risks persisted for 25 or more years following radiotherapy (RR, 2.3; 95% CI, 0.5-16.5; P =.03 for trend with dose). Treatment with alkylating agents alone resulted in a reduced risk (RR, 0.6; 95% CI, 0.2-2.0) of breast cancer, and combined alkylating agents and radiotherapy in a 1.4-fold (95% CI, 0.6-3.5) increased risk. Risk of breast cancer decreased with increasing number of alkylating agent cycles (P =.003 for trend). Risk also was low (RR, 0.4; 95% CI, 0.1-1.1) among women who received 5 Gy or more delivered to ovaries compared with those who received lower doses., Conclusions: Hormonal stimulation appears important for the development of radiation-induced breast cancer, as evidenced by the reduced risk associated with ovarian damage from alkylating agents or radiation. The high radiation-related risk, which did not diminish at the highest doses or the longest follow-up, however, suggests the need for lifetime surveillance and programs of patient and public awareness.

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.

Background: We attempted to determine factors contributing to the extent of initial curative resection for colon cancer in a population-based cohort. Total abdominal colectomy with ileorectal anastomosis (TAC-IR) may be considered for young patients or those with a colorectal cancer family history to prevent metachronous lesions and facilitate surveillance., Methods: All Ontario patients newly diagnosed with colon cancer over 12 months beginning in July 1997 were staged at the time of surgery. The extent of resection was compared with variables, including familial risk obtained from the Ontario Familial Colon Cancer Registry., Results: Complete staging was possible for 86% of patients. A total of 1223 patients had a potentially curative resection: 17%, 46%, and 36% were stage I, II, and III, respectively. Patients were more likely to receive a TAC-IR if they were < or = 50 years old (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.8-6.6), if they had a synchronous lesion (OR, 28.37; 95% CI, 12.2-61.2), or if they were at a teaching hospital (OR, 2.8; 95% CI, 1.6-4.7), but not if they had a family history (OR,.7; 95% CI,.3- 1.5)., Conclusions: Young age, teaching hospital, and multiple cancers but not family history were important factors for performing a TAC-IR.

Purpose: To assess the risk of fatal and nonfatal myocardial infarction (MI) after breast-conserving surgery (BCS) and radiation therapy (RT) for left-sided breast cancer., Patients and Methods: A hospital-based retrospective cohort linkage study of all breast cancer patients registered at the Princess Margaret Hospital (PMH), Toronto, Canada, between 1982 and 1988 who were treated with postlumpectomy RT was performed. Available identifiers for the study cohort were linked to two province-wide health files: the Canadian Institute for Health Information Hospitalization File and the Ontario Mortality Database. Admissions to hospital for MI and deaths attributable to MI were identified. The relevant original health records were abstracted to verify the diagnosis of MI according to diagnostic criteria used in the World Health Organization multinational monitoring of trends and determinants in cardiovascular disease (MONICA) project. We compared incidence of MI in the study cohort with the general population and incidence of MI after therapy for left- versus right-sided breast cancer., Results: A cohort of 2,128 patients was identified. The median length of follow-up was 10.2 years. The incidence of MI in the study cohort was comparable to that in an age-matched general population of women in Ontario. There were 70 coronary events among 56 patients after breast irradiation. According to MONICA criteria, 53 and six events were characterized as definite and possible MIs, respectively. Eleven events did not satisfy MONICA criteria for MI. Twenty-six patients treated for left-sided and 23 patients treated for right-sided breast cancer experienced at least one definite or possible MI (log-rank test, P =.66). There were eight fatal MIs among the left-sided group and six among the right-sided group. There was no excess of other cardiac diseases among patients who received left-sided radiotherapy compared to the right-sided group., Conclusion: We have found no evidence for excess morbidity and mortality from coronary artery disease among women treated with RT to the left breast after BCS at 10.2 years of follow-up. Longer follow-up is required to confirm that excess cardiac disease has been completely avoided.

Background: Lung cancer is a frequent cause of death in patients cured of Hodgkin's disease, but the contributions of chemotherapy, radiotherapy, and smoking are not well described. We quantified the risk of treatment-associated lung cancer, taking into account tobacco use., Methods: Within a population-based cohort of 19 046 Hodgkin's disease patients (diagnosed from 1965 through 1994), a case-control study of lung cancer was conducted. The cumulative amount of cytotoxic drugs, the radiation dose to the specific location in the lung where cancer developed, and tobacco use were compared for 222 patients who developed lung cancer and for 444 matched control patients. All statistical tests were two-sided., Results: Treatment with alkylating agents without radiotherapy was associated with increased lung cancer risk (relative risk [RR] = 4.2; 95% confidence interval [CI] = 2.1 to 8.8), as was radiation dose of 5 Gy or more without alkylating agents (RR = 5.9; 95% CI = 2.7 to 13.5). Risk increased with both increasing number of cycles of alkylating agents and increasing radiation dose (P for trend <.001). Among patients treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP), risk increased with cumulative amounts of mechlorethamine and procarbazine (P<.001) when evaluated separately. Statistically significantly elevated risks of lung cancer were apparent within 1-4 years after treatment with alkylating agents, whereas excess risk after radiotherapy began 5 years after treatment and persisted for more than 20 years. Risk after treatment with alkylating agents and radiotherapy together was as expected if individual excess risks were summed. Tobacco use increased lung cancer risk more than 20-fold; risks from smoking appeared to multiply risks from treatment., Conclusions: Past treatments with alkylating agents and radiation therapy for Hodgkin's disease were associated with an increased risk of lung cancer in a dose-dependent and additive fashion. The precise risk estimates, however, should be interpreted cautiously, given the possible residual and enhancing effects of tobacco.

Purpose: A population-based cohort study of soft tissue sarcoma of the extremities (STSE) in Ontario, Canada was conducted using linked administrative databases., Methods and Materials: Electronic administrative databases were linked from the Ontario Cancer Registry, the Canadian Institute for Health Information, and Radiation Oncology Research Unit database of radiation therapy (RT) records., Results: The definitive surgery was amputation for 6.0%, resection for 60.9%, biopsy for 7.5%; the remainder had no surgical record. Adjuvant RT was administered to 40.2% of cases. Among cases initially treated by surgical resection, 2.0% later underwent amputation and 9.5% underwent further resection during follow-up. The adjusted odds ratio (OR) for amputation as definitive surgery was 2.3 (1.19, 4.45) in eastern Ontario relative to Toronto. The likelihood of adjuvant RT among those not registered at a cancer centre within 3 months of diagnosis was decreased (OR = 0.20 (95% CI (0.13, 0.30)) relative to those registered. The adjusted relative risk of amputation at any time following diagnosis was 3.48 (95% CI (1.63, 7.46)) among cases not attending a cancer centre. The adjusted relative risk of death was 1.4; 95% CI (1.1, 1.7) among those not attending a cancer centre., Conclusions: Cases not seen at a multidisciplinary cancer centre within 3 months following diagnosis of STSE have an increased relative risk for amputation at any time, and for death due to any cause. Many hypotheses for further study are suggested by the results of this analysis.

Purpose: To describe (1) the use of surgery and radiotherapy (RT) in the treatment of patients with glioblastoma (GBM) in Ontario, (2) survival, and (3) proportion of survival time spent in the hospital after diagnosis., Methods and Materials: We performed a population-based cohort study of all Ontario Cancer Registry (OCR) cases of GBM diagnosed between 1982 and 1994. We linked OCR records, hospital files containing surgical procedure codes from the Canadian Institute for Health Information, and province-wide RT records. We studied the odds of treatment using multivariate logistic regression. We expressed the time spent in the hospital as the mean number of days per case, and as a proportion of the interval between diagnosis and death, or 24 months following diagnosis, whichever came first. We used the life-table method and Cox proportional hazards regression to describe survival., Results: The proportion of patients with GBM undergoing any surgery directed at the tumor varied with age (p < 0.0001) and region of residence (p < 0.0001). The proportion undergoing RT varied with age (p < 0.0001), region of residence (p < 0.0001), and year of diagnosis (p = 0.01). RT dose > or = 53.5 Gy varied with age (p < 0.0001), region of residence (p < 0.0001), and year of diagnosis (p = 0.0002). Median survival was 11 months among patients receiving RT and 3 months among those not receiving RT. The percentage of survival time spent in the hospital was similar among those who received from 49.5 to < 53.5 Gy, compared to > or = 53.5 Gy. Overall survival and the adjusted relative risk of death varied with age and region of residence., Conclusion: We observed practice variation in the treatment of patients with GBM according to age, region of residence, and year of diagnosis. Survival did not increase during the study period. The variation in RT dose between those receiving from 49.5 to < 53.5 Gy compared to > or =53.5 Gy was not paralleled by variation in survival between regions where one or the other of the dose ranges predominated, nor was variation in dose ranges among the regions paralleled by variation in the proportion of survival time spent in the hospital.

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.

The Ontario Familial Colon Cancer Registry (OFCCR) is a novel registry that collects family history information, epidemiologic data, blood samples and tumour specimens from a population-based sample of colorectal cancer patients and their families. Families are classified as either high familial risk, intermediate familial/other risk or low (sporadic) risk for colorectal cancer. Obtaining high response rates in genetic family studies is especially challenging because of both the time commitment required and issues of confidentiality. The first-year response rate was 61%, resulting in 1,395 participating probands. In an attempt to assess potential response bias, we compared participants with non-participants. The age and sex of participants did not differ from non-participating probands; however, cases in rural areas were somewhat more likely to participate. To date, 57% of 1,587 relatives participated; females were more likely to participate, and relatives of low familial risk were least likely to participate. The OFCCR is an excellent resource that will facilitate the study of genetic and environmental factors associated with colorectal cancer.

Some colorectal tumors with wild-type adenomatous polyposis coli gene have activating mutations in beta-catenin (encoded by CTNNB1) that result in decreased phosphorylation by GSK-3beta and increased signaling through the Tcf/Lef transcription factors. To investigate the relationship between CTNNB1 mutations and underlying pathways of genomic instability, we examined 80 colorectal cancers stratified by the presence or absence of microsatellite instability (MSI). CTNNB1 mutations were identified in 13 (25%) of 53 cancers with high frequency MSI (MSI-H), including 12 point mutations at exon 3 phosphorylation sites (codons 41 and 45) and one deletion of the entire exon 3 degradation box. No CTNNB1 mutations were identified in 27 microsatellite stable or low frequency MSI (MSI-L) colorectal cancers (P < 0.01). In contrast, CTNNB1 mutations were identified in 3 of 9 (33%) MSI-H and 10 of 20 (50%) MSS/MSI-L endometrial carcinomas, suggesting a more generalized involvement in these tumors. Only six (46%) of the endometrial carcinoma CTNNB1 mutations occurred at residues directly phosphorylated by GSK-3beta, and only one of these was at either codon 41 or 45. All point mutations in MSI-H cancers were transitions, whereas 64% of those in MSS/MSI-L cancers were transversions (P < 0.01). The differences in the mutation profiles suggest that there may be molecular fingerprints of CTNNB1 mutations, determined by biological factors related to both tumor type and underlying pathways of genomic instability.

Surgical reduction of the female breast (reduction mammaplasty) is very common in plastic surgery. The purpose of this study was to determine whether women who have undergone breast reduction surgery are at the same, greater, or lesser risk of developing breast cancer than women who have not undergone breast reduction surgery. This study incorporates a population-based, non-concurrent cohort linkage methodology. The Canadian Institute for Health Information hospital records were used to identify all Ontario women who had undergone breast reduction surgery in Ontario between 1979 and 1992. Three computerized probabilistic record linkages were performed. The first linkage was between a file of the 28,042 Ontario women who had undergone bilateral breast reduction surgery between April 1, 1979, and December 31, 1992, and a file of incident cancer cases among Ontario women for the calendar period 1979 to 1993. Follow-up of the cohort was undertaken starting from the date of breast reduction surgery, and vital status was ascertained as of December 31, 1993, by record linkage with the Ontario Mortality Database maintained at the Ontario Cancer Registry. The incidence of cancer in the Ontario breast reduction cohort was compared with the cancer incidence of the general Ontario population after appropriate adjustments for age and calendar time period. The expected number of cancers was calculated using the "PERSON YEARS" computer program. Within the cohort, followed for an average of 6.5 years after bilateral breast reduction surgery, 101 breast cancers were observed and 165.8 were expected, for a standardized incidence ratio of 0.61 (0.50 to 0.74, 95 percent confidence interval). This effect was independent of patient age at breast reduction. This study demonstrates that there is no increased risk of breast cancer after bilateral breast reduction surgery and, in fact, a significant decreased risk existed in women followed for an average of 6.5 years.

Reduction mammaplasty is one of the most common procedures performed by plastic surgeons in Canada. In a recent study of 27,500 women in the province of Ontario who underwent breast reduction surgery, 105 women were identified who developed breast cancer after reduction mammaplasty. The purpose of this study was to compare women who had breast cancer and had a previous breast reduction with women who had breast cancer but did not have a breast reduction. Specifically, we wanted to document patient demographics, cancer type, surgical and nonsurgical treatment, and eventual outcome. A comparison group of non-breast reduction women was taken from the cohort of breast cancer patients in the province of Ontario, and the two groups were matched for age, year of diagnosis, and place of diagnosis. It was found that (1) the average age at diagnosis of breast cancer is significantly younger for women who have had previous breast reduction surgery than for those who have not; (2) the median interval between breast reduction and cancer is 5 years; (3) the type, location, and side of breast cancers are similar in the two groups of women; (4) breast reduction does not significantly increase or decrease survival rate from breast cancer; and (5) women who have had breast reduction receive the same treatment for their breast cancer as women who have not had reduction mammaplasty.

In a recent study involving 27,500 women who had breast reduction surgery in Ontario, Canada, 17 women who were diagnosed as having breast cancer at the time of their breast reduction surgery were identified. The aims of this study were to (1) describe a population-based series of patients who had breast cancer diagnosed at the time of breast reduction, (2) describe the treatment of these cancers, and (3) compare their survival rate with survival in patients in the general population who had breast cancer. Information about these women, their treatment, and outcome was extracted from hospital records, pathology reports, and reports from regional cancer centers. The chance of finding an invasive breast cancer at the time of breast reduction was 0.06 percent, which is lower than what has been reported previously. Sixty-seven percent of these women were treated with total mastectomy. In the remaining 33 percent, who were treated with partial mastectomy, the entire tumor was removed at the time of breast reduction. Fifty percent of the women were treated with radiation, and 25 percent were treated with chemotherapy or hormonal therapy. Compared with women in the general population of Ontario who have breast cancer, women whose breast cancer is discovered during breast reduction surgery are more likely to be treated with complete mastectomy and less likely to be treated with radiotherapy or chemotherapy. Seventy-one percent of the breast reduction group were axillary node-negative at diagnosis, compared with 58 percent in the general population of women with breast cancer. Survival from breast cancer in women diagnosed at the time of breast reduction (88 percent, 5-year survival) was better than survival from breast cancer in the general population (77 percent). These findings suggest that cancers found in women at the time of breast reduction are less advanced, possibly because they are diagnosed at an earlier stage.