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We evaluated the risk of bladder cancer in a cohort of 79 280 Swedish men hospitalised for benign prostatic hyperplasia (BPH), identified in the Swedish Inpatient Register between 1964 and 1983 and followed until 1989 via multiple record linkages with nationwide data on cancer registry, death and emigration. Standardised incidence ratios (SIRs), the ratios of the observed to the expected numbers of incident bladder cancers, were used to calculate the risk associated with BPH. The expected number was calculated by multiplying the number of person-years by the age-specific cancer incidence rates in Sweden for each 5-year age group and calendar year of observation. Analyses were stratified by BPH treatment, latency, calendar year and presence of genitourinary (GU) comorbid conditions. After excluding the first 3 years of follow-up after the index hospitalisation, we observed 506 incident bladder cancer cases during follow-up in the cohort. No overall increased risk of bladder cancer was apparent in our main analysis involving the entire BPH cohort. However, among BPH patients with transurethral resection of the prostate (TURP), there was an increased risk in all follow-up periods; SIRs of bladder cancer during years 4–6 of follow-up was 1.22 (95% confidence interval=1.02–1.46), 1.32 for 7–9 years of follow-up, and 1.47 for 10–26 years of follow-up. SIRs of bladder cancer among TURP-treated BPH patients were particularly elevated among those with comorbid conditions of the GU tract (e.g., stone, infection, etc.); 1.72, 1.74 and 2.01 for 4–6, 7–9, 10–26 years of follow-up, respectively, and also for those whose diagnoses occurred before 1975, when TURP was more likely to be performed by a urologist than a general practitioner: 1.87, 1.90 and 1.74, respectively. These findings suggest that BPH overall is not associated with bladder cancer risk. However, among men treated with TURP, particularly those with other comorbid GU tract conditions, risk of bladder cancer was elevated.British Journal of Cancer (2007) 96, 1475–1479. doi:10.1038/sj.bjc.6603730 www.bjcancer.com Published online 1 May 2007 [ABSTRACT FROM AUTHOR]

Features a population-based case-control study of risk factors for cancers of the esophagus and gastroesophageal junction in Sweden. Increased incidence of adenocarcinomas in western populations; Association between Barrett's esophagus and gastroesophageal reflux disease.

Background: Results from randomized trials of antioxidant supplementation have cast doubt on observational data linking diets high in antioxidants to a reduced risk of cardiovascular diseases. We hypothesized that supplementation of one or a few antioxidants might not simulate the complex actions of all antioxidants in the human diet. We therefore investigated the association between dietary Non Enzymatic Antioxidant Capacity (NEAC), reflecting the antioxidant potential of the whole diet, and the risk of myocardial infarction (MI)., Methods: In the Swedish National March Cohort, 34 543 men and women free from cardiovascular diseases and cancer were followed through record linkages from 1997 until 2010. NEAC was assessed with a validated food-frequency questionnaire at baseline. The distribution of NEAC was categorized into sex-specific quartiles. We fitted multivariable Cox proportional hazards regression models to estimate hazard ratios (HRs) with 95% confidence intervals (CIs)., Results: During a mean follow-up time of 12.7 years, we identified 1142 incident cases of MI. Successively higher quartiles (Qs) of dietary NEAC were accompanied by a monotonic trend of decreasing MI incidence, both for overall MI (HR Q4 vs Q1: 0.77; 95% CI: 0.61-0.96; p for trend = 0.008) and non-fatal MI (HR Q4 vs Q1: 0.72; 95% CI: 0.56-0.92; p for trend = 0.004). No such association was found for fatal MI., Conclusions: A diet rich in antioxidants might protect from MI.

Background: An increased prevalence of gastric premalignant abnormalities was reported among relatives of gastric cancer (GC) patients, with rather unexplored clinical significance., Methods: In Swedish computerized pathology registers, we identified, as 'index' persons, 232 681 patients who were born after 1931 and underwent endoscopic examination with stomach biopsy between 1979 and 2014. Through linkage with the Multi-Generation Register, we compiled a cohort consisting of 903 337 first-degree relatives of these biopsied patients. The relatives were grouped according to their 'family histories', defined as the first gastric mucosal diagnosis of the index person or GC family history known before that. Standardized incidence ratios (SIRs) provided comparisons with the matched general population. For internal comparisons with relatives with 'normal/minor changes' mucosal family history, hazard ratios (HRs) were derived from adjusted Cox regression modelling., Results: During follow-up, 1302 relatives developed GC. Crude incidence rates of non-cardia GC were 7.7 × 10-5 year-1 for the 'normal/minor changes' family history group (SIR = 1.0), 11.2 to 12.6 × 10-5 year-1 for precancerous changes groups (atrophic gastritis/intestinal metaplasia/dysplasia, SIR = 1.5 to 1.6), and 18.4 × 10-5 year-1 for those with a family history of GC (SIR = 2.3). HRs derived from Cox models corroborated the family history-related risk pattern, with the most conspicuous trend observed among siblings-a family history of any precancerous changes and GC was associated with, respectively, a 2.5-fold and a 3.8-fold increment in non-cardia GC hazard, compared with siblings of index persons with 'normal/minor mucosal changes'., Conclusions: The precancerous mucosal abnormalities recorded in a person's first-degree relatives may improve GC risk stratification for this person.

Viral diagnosis of respiratory tract infections has so far required sampling by health professionals,hampering large-scale epidemiological studies of virus-specific disease outcomes. As part of a population-based, prospective study of work-related risk factors for transmission of viral infections (SWEDE-I), we developed a scheme for self-sampling with nasal swabs. Random selection from the gainfully employed population of a medium-sized town in central Sweden resulted in a study cohort of 2,237 men and women aged 25 to 63 years. From September 2011 through May 2012, the cohort reported all instances of respiratory tract infection or gastroenteritis and participants concomitantly sent self-sampled nasal swabs for analysis using regular mail. Diagnosis of 14 viruses was performed. A total of 1,843 samples were received. The week-wise average delay between disease on set and arrival of the specimens at the laboratory varied between four and six days, and the corresponding median delay was between 3.5 and six days. In line with previous community-based studies, picorna- and coronaviruses dominated in specimens obtained from the self-sampling scheme. The results of self-sampling were contrasted to those from contemporaneous routine clinical sampling, on the same age group, in the adjacent Stockholm county. Although higher proportions of positive samples for respiratory syncytial virus and influenza were observed in the clinical sampling scheme, estimations of seasonality for influenza A and picornaviruses derived from both schemes were similar. Our findings show that nasal self-sampling is feasible in large-scale surveillance of respiratory infections and opens new prospects for population based,virologically verified research on virus spread,burden of disease, and effects of environmental factors or interventions.

Background: The treatment of coagulopathy and bleeding in severe trauma requires rapid delivery of large amounts of plasma to emergency wards. The resulting need for adequate supplies of nonfrozen or thawed plasma has consequences for storage strategies. Using extensive population data from a setting where both fresh-frozen plasma (FFP) and cold-stored liquid plasma were used, this study investigates whether there is an association between short-term mortality after receipt of FFP or liquid plasma of different storage times., Methods: A cohort of 84,986 Swedish patients was followed up from first recorded allogenic plasma transfusion for 14-day mortality. Associations with exposure to FFP were expressed as relative risks adjusted for patient characteristics, total transfusions, hospital, and calendar year. For non-FFP, the units given to patients who died and matched patients who survived were compared for their duration of storage., Results: The relative risk of exposure to FFP was 1.19 (95% confidence interval: 1.12-1.27, p < 0.0001), with the risk elevation confined to the earlier calendar years of the study. There was no evidence of any effect of storage time of non-FFP. In analyses of all plasma types, FFP from male donors had lowest risk., Conclusions: Compared with exclusive use of never-frozen plasma, FFP was associated with increased short-term mortality in the era before leukocyte depletion. FFP from female donors had a significantly higher risk than male FFP. For non-FFP, duration of storage was unrelated to mortality. These findings can help to inform policies for managing high plasma demand in critical care.

Background: Plasma from female donors has been implicated in the sometimes fatal complication known as transfusion-related acute lung injury. In studies of patients in intensive care units, worsened gas exchange of the lungs has also been attributed to female plasma. Despite a lack of population-based evidence, policies have already been introduced to exclude female donor plasma., Study Design and Methods: Short-term mortality after plasma transfusion was investigated using data from the Scandinavian Donations and Transfusions (SCANDAT) database. A cohort of 92,565 patients in 30 Swedish hospitals were followed for 14 days after their first plasma transfusion. The relative risk (RR) of death in recipients of female plasma compared to recipients of only male plasma was estimated from Poisson regression., Results: Recipients had median age 70 years, received a mean of 4.4 plasma units, and had an overall 14-day mortality of 8.43%. Sixty-eight percent were exposed to female plasma, with a 14-day mortality of 8.85% compared to 7.53% in the nonexposed group. After adjustment for potential confounding factors, the RRs were 1.16 (confidence interval [CI], 1.06-1.27) and 1.32 (CI, 1.17-1.49) for those receiving 3 to 4 and 5 or more units of female plasma, respectively. Risk estimates were increased in an analysis of deaths with a concomitant discharge diagnosis involving the respiratory or circulatory system or an adverse reaction., Conclusions: This large population-based cohort study of unselected patients suggests that transfusion of plasma from female donors confers a short-term survival disadvantage on recipients.

Objectives: Mental symptoms and impaired quality of life commonly occur in patients treated for hyperthyroidism. Our aim was to determine whether a history of hyperthyroidism implies an increased risk of suicide., Design: Historic cohort study of 43,633 patients treated with radioiodine or surgery for hyperthyroidism between 1950 and 2005. The majority of the radioiodine-treated patients came from Stockholm. Two comparison cohorts consisted of 44,921 patients registered with an operation for atoxic nodular goitre between 1965 and 2005, and 354,861 patients with a cholecystectomy between 1965 and 2001., Methods: Subjects were followed from the date of diagnosis until death, emigration or end of follow-up. Information on outcome was obtained from population and health registers., Results: The number of observed suicide deaths was 134 in the study cohort. A naive comparison with the age-, sex- and calendar period-matched general Swedish population yielded a moderately increased standardized mortality ratio (SMR), but stratifications revealed that the excess was mainly driven by women from Stockholm, whose baseline suicide risk was higher than for women in the rest of Sweden. Using the population rates from Stockholm, the SMR among Stockholm women with Graves' disease was 1.14 (95% confidence intervals (CI) 0.66-1.86) and toxic goitre 0.99 (95% CI 0.51-1.72). A direct comparison between the study cohort and the combined comparison cohorts, with multiple adjustments (including adjustment for residence in Stockholm), yielded a relative risk of suicide of 0.93 (0.68-1.26)., Conclusions: This study did not confirm an increased risk of suicide among patients treated for hyperthyroidism.

No increased risks of specific types of cancer following breast implantation have been consistently reported, but data on risk beyond 15 years are limited. We have pooled the results of 2 nationwide cohort studies of 3,486 Swedish and 2,736 Danish women who underwent cosmetic breast implantation between 1965 and 1993. Cancer incidence through 2002 was ascertained through nationwide cancer registries. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated to compare cancer incidence among women with implants with women in the general population. Mean duration of follow up was 16.6 years (range 0.1-37.8 years). Over 50% of women were followed for 15 years or more after breast implantation and 13.3% for at least 25 years. There was a reduced incidence of breast cancer (SIR=0.73; 95% CI 0.58-0.90), whereas lung cancer was above expectation (SIR=1.64; 95% CI 1.10-2.36). The increased risk of lung cancer is expected due to the high prevalence of smoking among the women with implants in our study. With respect to other site-specific cancers, no significantly increased or decreased SIR was observed. This study, which includes women followed for almost 4 decades, represents the longest follow up of women with cosmetic breast implants to date. The results provide no evidence of an association between breast implants and any type of cancer., (Copyright (c) 2008 Wiley-Liss, Inc.)

Epidemiologic evidence does not support a consistently increased cancer risk among women with cosmetic breast implants, but few studies have assessed risk beyond 15 years. Swedish women who underwent cosmetic breast implantation for the first time between January 1, 1965, and December 31, 1993 (N = 3486), were followed through December 31, 2002. Cancer incidence was ascertained through the nationwide Swedish Cancer Registry. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated to compare cancer incidence of women with implants with women in the general population. Mean follow-up among women with breast implants was 18.4 years (range = 0.1-37.8 years). The incidence of breast cancer was below expectation (SIR = 0.7, 95% CI = 0.6 to 1.0), whereas lung cancer was above expectation (SIR = 2.2, 95% CI = 1.3 to 3.4). With respect to cancer overall and all other specific cancer sites, including brain cancer and sarcoma, non-Hodgkin lymphoma, and multiple myeloma, no statistically significantly increased or decreased SIRs were observed. Stratification by duration of follow-up revealed no statistically significantly increased or decreased SIR, with the exception of a two- to threefold excess of lung cancer among women followed for more than 15 years, which would be expected due to the high prevalence of smoking among the Swedish women with implants in our study.

Objective: We constructed a simple questionnaire that, with a minimum of questions, could accurately and reliably identify women with genital organ prolapse., Study Design and Setting: Two hundred women with confirmed genital organ prolapse and 199 outpatients with various gynecologic symptoms but no objective prolapse answered 13 questions perceived to be valuable for the diagnosis. With stepwise backward logistic regression, the discriminatory ability of a successively abbreviated set of questions was assessed. The resulting short questionnaire was tested in a new population-based sample of 282 women participating in a screening survey., Results: A final five-item questionnaire retained 94% of the predictive value of all 13 questions and had 92.5% sensitivity and 94.5% specificity in the first group of women. When the questionnaire was used in the subsequent population-based survey, the sensitivity and specificity values were 66.5% and 94.2%, respectively. Most missed cases had stage I prolapse., Conclusion: Although the sensitivity of the test was moderate, the specificity, and hence the ability to rule in cases, was satisfactory. The test is suitable for case finding in epidemiologic studies.

This study examined associations between childbearing and risk of scleroderma by using national population-based registry data from Sweden. Women with a discharge diagnosis of scleroderma from 1964 to 1999 (n = 2,149) were identified in the Swedish Inpatient Register. These cases were matched by year and month of birth and region of residence to as many as five controls obtained from the Multi-Generation Register. Pregnancy history (number of births, age at each birth) was restricted to births before the first scleroderma-related hospitalization for cases and the corresponding age for their matched controls. Risk estimates, measured by the odds ratio and 95% confidence interval, were obtained by using conditional logistic regression. Nulliparity was associated with an increased risk of scleroderma (odds ratio = 1.37, 95% confidence interval: 1.22, 1.55). Risk decreased with increasing number of births. Similar results were found when analyses were limited to births up to 2 years or up to 5 years before hospitalization. Among parous women, younger age at first birth was associated with an increased risk of scleroderma. The association between lower parity and increased risk of scleroderma could reflect subfecundity caused by scleroderma before disease became clinically evident, possible common causes of infertility and scleroderma, or a protective effect of pregnancy through an unknown mechanism.

Objective: Researchers have speculated that surgical excision of lymphoid tissue, such as appendectomy, early in life might confer an increased risk of cancer. In this study, we determined the risks of cancer for people who had appendectomy performed during childhood., Methods: We studied the risk of cancer in a large Swedish cohort of children who had appendectomy performed during the period of 1965-1993. Standardized incidence ratios (SIRs) were computed using age-, gender-, and period-specific incidence rates derived from the entire Swedish population as comparison. Hospital discharge diagnosis data were used to examine cancer risks by categories of surgery, medical conditions, and type of appendicitis. The average length of follow-up was 11.2 years., Results: We found no excess overall cancer risk but noted a significant excess for stomach cancer (SIR: 2.45; 95% confidence interval [CI]: 1.1-4.8) and a borderline increase of non-Hodgkin's lymphoma (NHL; SIR: 1.55; 95% CI: 1.0-2.3). The elevated risks for both cancers were only evident 15 or more years after appendectomy (stomach cancer, SIR: 3.82; 95% CI: 1.7-7.5; NHL, SIR: 2.49; 95% CI: 1.4-4.2)., Conclusions: It is reassuring that there was no overall increase of cancer several years after childhood appendectomy. Increased risks for NHL and stomach cancer, occurring 15 or more years after appendectomy, were based on small absolute numbers of excess cancers. As 95% of the subjects were younger than 40 years at exit, this cohort requires continuing follow-up and monitoring.

Background: Individuals with Down syndrome (DS) have a predisposition to leukemia and possibly other cancers and excess mortality from other conditions, but information on the magnitude of risk associated with specific cancers or causes of death is sparse., Methods: Mortality experience and cancer incidence were evaluated in a combined cohort of 4872 individuals with a hospital discharge diagnosis of DS in Sweden (1965-1993) or Denmark (1977-1989) by linkage to national cancer and vital statistics registries. Standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs) were estimated by comparison with age, sex, and calendar-year expected values., Results: Individuals with DS had an increased risk of incident acute lymphocytic (SIR, 24.2; 95% confidence interval [CI], 15.2-36.6; n = 22) and acute nonlymphocytic (SIR, 28.2; 95% CI, 15.7-48.3; n = 14) leukemias. Risks of testicular cancer (SIR, 3.7; 95% CI, 1.0-9.4; n = 4) and liver cancer (SIR, 6.0; 95% CI, 1.2-17.5; n = 3) were also elevated. Individuals with DS also experienced elevated mortality attributed to stomach cancer (SMR, 6.4; 95% CI, 1.7-16.4; n = 4), dementia and Alzheimer disease (SMR, 54.1; 95% CI, 27.9-94.4), epilepsy (SMR, 30.4; 95% CI, 13.9-57.7), ischemic heart disease (SMR, 3.9; 95% CI, 2.7-5.4), other heart disease (SMR, 16.5; 95% CI, 11.0-23.7), cerebrovascular disease (SMR, 6.0; 95% CI, 3.5-9.6), infectious diseases (SMR, 12.0; 95% 6.0-21.4), and congenital anomalies (SMR, 25.8; 95% CI, 21.0-31.4)., Conclusions: Individuals with DS have a substantially increased risk of mortality due to specific causes and may have an elevated risk of other incident cancers in addition to leukemia. These results provide clues regarding chromosome 21 gene involvement in diseases that complicate DS and are important for disease detection and care of affected individuals.

Background: As knee implants become more common, it is important to study their potential health risks. We investigated cancer occurrence in a nationwide population-based cohort of 30,011 patients who underwent knee replacement surgery in Sweden from 1980 to 1994., Methods: Patients were followed from 1 year after the date of their surgery through December 31, 1995, accruing 122,616 person-years of observation. The average follow-up time was 4.3 years, with 2365 patients followed for 10 years or more., Results: Overall cancer incidence was not elevated compared with the general population of Sweden (standardized incidence ratio [SIR] = 1.03; 95% confidence interval [CI] = 0.98-1.08). A reduced rate for all respiratory cancers (SIR = 0.73; 95% CI = 0.59-0.91) and for lung cancer (SIR = 0.73; 95% CI = 0.58-0.91) was found among both men and women. Elevated rates were found for prostate (SIR = 1.20; 95% CI = 1.06-1.34) and bone cancer (SIR = 6.00; 95% CI = 1.24-17.52) in men. The bone cancer excess was based on three observed cases, two of which occurred at a site unrelated to the implant and the site of the third tumor is unknown. Rates of connective tissue cancer and leukemia-lymphoma were not elevated significantly among knee implant recipients. Long-term follow-up (>or= 10 years) did not show a significant excess risk for all cancer (SIR = 1.10; 95% CI = 0.86-1.38) or for any site-specific cancer, including bone cancer, lymphoma, or leukemia. Subgroup analyses for patients with rheumatoid arthritis produced results similar to the overall results., Conclusions: This epidemiologic study of cancer risk among patients with knee implants is the largest to date. It provides evidence that the incidence of cancer among patients with knee implants is similar to that of the general population. Continued follow-up of this cohort is warranted to evaluate further potential long-term effects of these implants., (Copyright 2002 American Cancer Society.)

A retrospective cohort study was performed in Sweden to evaluate the possibility that an individual symptom or constellation of illness symptoms related to silicone occurs in women after breast implant surgery. A random sample (n = 2500) of all women in the Swedish national implant registry who underwent breast augmentation surgery with alloplastic breast implants during the years 1965 through 1993 was compared with a sample (n = 3500) of women who underwent breast reduction surgery during the same period, frequency matched to the implant patients for age and calendar year at the time of surgery. In total, 65 percent of the breast implant patients (n = 1546) and 72 percent of the breast reduction patients (n = 2496) completed a self-administered questionnaire covering 28 rheumatologic and other symptoms and lifestyle and demographic factors. Practically all of the 28 symptoms inquired about were reported more often by women in the breast implant cohort, with 16 (57 percent) significantly more common in breast implant recipients. In contrast, few significant differences or consistent patterns were observed in the length of time since the implant and in the type (silicone or saline) or volume of the implant. Although women with breast implants report a multitude of symptoms more often than women who have breast reduction surgery, the lack of specificity and absence of dose-response relationships suggest that the excess of reported symptoms is not causally related to cosmetic implants.

Epidemiologic studies have found no association between breast implants and cancer or well-defined connective tissue diseases. However, women with cosmetic breast implants continue to report specific as well as nonspecific physical and psychological symptoms after receiving their implants. In an attempt to determine whether local complications of implantation may contribute to this excess of symptom reporting, the authors studied a large cohort of women in Sweden with cosmetic breast implants (n = 1280) and a comparison cohort of women who had cosmetic breast reduction surgery (n = 2211). Both groups of women had operations between 1969 and 1996. Medical record reviews of local complications revealed that approximately 31 percent of the women with cosmetic breast implants had an implant change, implant leakage, or a capsulotomy. Capsulotomies occurred more often in women who were age 35 or older at the time of the operation, had ever smoked, and had implants with a smooth surface. On self-administered questionnaires, symptoms were reported more often by the women who had implants regardless of whether they had local complications. Twenty of the 28 symptoms occurred more frequently among women with local complications and breast implants, compared with the women in the breast reduction comparison group or the women with breast implants but no local complications. This study suggests that local complications, particularly capsular contractures as indicated by capsulotomy, may be an important factor to consider when studying symptom reporting among women with breast implants.

To determine whether women with cosmetic breast implants have distinct demographic, lifestyle, and reproductive characteristics that put them at increased risk for subsequent morbidity, the authors compared 1,369 such women to 2,211 women who had undergone breast reduction surgery, and to a random sample of 49,262 women from the general population of Sweden. Information was collected through self-administered questionnaires, and comparisons were made using the prevalence odds ratio. Women with cosmetic breast implants were significantly (p <0.05) more likely to be current smokers, have a lower body mass index, have had a prematurely terminated pregnancy (induced abortion or miscarriage), and have had fewer live births than either women who underwent breast reduction or women from the general population. Type of implant (silicone gel or saline) did not modify the associations. Regardless of the comparison group used, studies of the health effects of breast implants need to consider that women who undergo cosmetic breast implantation have certain distinct characteristics.

Background: Our aim was to evaluate whether there is a healthy worker effect (HWE) for cancer incidence among women. HWE is a bias found in occupational studies that compare rates of disease among employed people to disease rates for the general population, which includes unemployed people (who may be less healthy than those who are employed)., Methods: Data from the 1960 and 1970 Swedish censuses were used to identify all 1,659,940 Swedish women who were employed in either year. They were followed during 1971-1989 through linkages to the national cancer and death registers. Standardized incidence ratios (SIRs) were computed comparing employed women to the 1,627,873 women who were not employed in either 1960 or 1970., Results: For the 545,857 women employed in both 1960 and 1970, the SIR for all cancers combined was 1.05 (1.04-1.06). When specific cancer sites were analyzed separately, the highest cancer risks were for cancers of the lung and bladder (SIR = 1.2) and reproductive organs (breast, ovary, endometrium, and cervix SIR = 1.1). Overall cancer risks were highest among full-time workers, younger workers, urban workers, and workers with the highest socioeconomic status (based on the woman's job title)., Conclusions: These results show no general HWE for cancer incidence among employed Swedish women.

Background: Previous reports have indicated an association between Barrett's metaplasia or adenocarcinoma of the oesophagus and colonic neoplasia, but the findings have been inconsistent. If true, such an association suggests common causal mechanisms., Aims: To test the hypothesis of an association between Barrett's metaplasia or adenocarcinoma of the oesophagus and colonic neoplasia., Methods: A population based, retrospective cohort study was performed on all Swedish patients with colon cancer diagnosed between 1958 and 1992. 538 500 person years at risk were reviewed among the 118 030 patients in the cohort (average follow up 4.6 years, median 2.1 years). The standardised incidence ratio (SIR), the ratio of the observed to the expected number of incident oesophageal adenocarcinomas, was used as a measure of relative risk. The expected number was derived from the entire Swedish population., Results: Eleven oesophageal adenocarcinomas were found during follow up in the cohort, as against 9.5 expected (SIR=1.2; 95% confidence interval 0.6-2.1). Analysis by latency intervals after diagnosis of colon cancer showed no trend towards increasing or decreasing risk over time. There were no important sex differences in relative risk., Conclusions: Results provide no support for a common link between colon cancer and oesophageal adenocarcinoma. Although the direct relation between colon cancer and Barrett's oesophagus was not looked at, a search for common aetiological factors or genetic defects may not be fruitful. Screening for colonic neoplasia among patients with malignant or premalignant oesophageal mucosa, or vice versa, may not be warranted.

Although self-administered questionnaires are major sources of information in epidemiology, comparatively little has been done to study practical aspects of design and mailing. The objective of this study was to evaluate various measures taken to increase the response rate. A questionnaire was mailed in July 1995 to a random sample (n = 2,000) of the Swedish population aged 20-79 years. Using a randomized factorial study design, the questionnaire and mailing procedures were changed in three ways: preliminary notification, length of the questionnaire, and mention of telephone contact. The overall questionnaire retrieval rate was 49%. Preliminary notification (adjusted odds ratio of receiving a completed questionnaire = 1.30, 95% confidence interval (CI) 1.08-1.56 relative to the absence of preliminary notification) and short length of the questionnaire (odds ratio = 1.24, 95% CI 1.04-1.48 relative to a long questionnaire) were both independently associated with a higher retrieval rate. Of eight possible combinations, the one comprising preliminary notification, a short questionnaire, and no mention of telephone contact gave the highest retrieval rate, 56%. The lowest retrieval rate, 40%, was observed for the combination of no preliminary notification, a long questionnaire, and mention of telephone contact. Young age, male sex, and urban residence significantly lowered the retrieval rate. Although there was a positive association between the questionnaire retrieval rate and partial nonresponse (missing answers in retrieved questionnaires), the marginal losses due to the latter did not cancel the gains by optimized mailing routines. Old age was the strongest determinant of partial nonresponse. The data provide evidence that design and mailing strategies, as well as demographic characteristics, may greatly influence the response rate of mailed epidemiologic questionnaires.

Although some studies have linked excess of Hodgkin's disease (HD) to tonsillectomy, the findings have not been consistent. In particular, risk of HD by age at tonsillectomy has not been fully evaluated, despite the notable change in immunologic function of the tonsils between childhood and adulthood. To evaluate the risk of HD and other lymphomas, associated with tonsillectomy according to age at surgery, a population-based cohort study was conducted. Using nationwide Swedish hospitalization records, 55,169 patients undergoing tonsillectomy with/without adenoidectomy (T/A) were identified during the period 1964-1983. By linkage with the nationwide Total Population, Migration, Cancer and Causes-of-Death registries, these patients were followed up for as long as 25 years. After exclusion of the first post-operative year, a total of 533 first primary-cancer cases was identified between 1965 and 1989. Small excess risk was observed for HD (20 cases, SIR = 1.4, 95% CI 0.9-2.2). HD risk was more pronounced among patients tonsillectomized before age 12 (7 observed vs. 1.7 expected, SIR = 4.1, 95% CI 1.6-8.4), but declined significantly with older ages at T/A. While our data suggest a small increase in HD among all patients undergoing T/A and a significant excess for those under age 12 at surgery, we cannot exclude the possibility that the excess may be due to factors underlying the disorders that led to surgery.

Background: Elevated risk of cancers of the stomach, colon, and buccal cavity, as well as of lymphoma and leukemia, have been reported for patients with pernicious anemia in case reports and hospital-based and cross-sectional studies., Methods: A cohort of 2021 men and 2496 women living in the Uppsala health care region in Sweden, discharged with a hospital diagnosis of pernicious anemia from 1965 to 1983, was followed for 20 years for subsequent risk of cancer., Results: A total of 553 cancers were diagnosed among these patients, significantly more than expected based on cancer standardized incidence rates (SIRs) in the general population (SIR = 1.4; 95% confidence interval [CI], 1.2-1.5). Most prominent were excesses for cancer of the stomach (SIR = 2.9; 95% CI, 2.4-3.5), esophagus (SIR = 3.2; 95% CI, 1.8-5.2), and pancreas (SIR = 1.7; 95% CI, 1.2-2.4) among men and women; myeloid leukemia among men (SIR = 4.4; 95% CI, 1.8-5.2); and multiple myeloma among women (SIR = 2.5; 95% CI, 1.1-4.9). An excess of gastric carcinoid tumors also was evident in this cohort. The risk of stomach cancer was highest in the first year after diagnosis of pernicious anemia (SIR = 7.4; 95% CI, 5.3-10.1), but an increased risk persisted throughout the follow-up period. The risk of esophageal cancer also remained elevated throughout the study period, although the risk of pancreatic cancer dropped off after 5 years., Conclusions: This study confirms the excess risk of gastric carcinoma and carcinoid tumors associated with pernicious anemia, and suggests that the susceptibility state may extend to esophageal and other cancers.