Alcohol consumption and risk of urothelial cell bladder cancer in the European prospective investigation into cancer and nutrition cohort.

Findings on the association between alcohol consumption and bladder cancer are inconsistent. We investigated that association in the European Prospective Investigation into Cancer and Nutrition cohort. We included 476,160 individuals mostly aged 35-70 years, enrolled in ten countries and followed for 13.9 years on average. Hazard ratios (HR) for developing urothelial cell carcinoma (UCC; 1,802 incident cases) were calculated using Cox proportional hazards models. Alcohol consumption at baseline and over the life course was analyzed, as well as different types of beverages (beer, wine, spirits). Baseline alcohol intake was associated with a statistically nonsignificant increased risk of UCC (HR 1.03; 95% confidence interval (CI) 1.00-1.06 for each additional 12 g/day). HR in smokers was 1.04 (95% CI 1.01-1.07). Men reporting high baseline intakes of alcohol (>96 g/day) had an increased risk of UCC (HR 1.57; 95% CI 1.03-2.40) compared to those reporting moderate intakes (<6 g/day), but no dose-response relationship emerged. In men, an increased risk of aggressive forms of UCC was observed even at lower doses (>6 to 24 g/day). Average lifelong alcohol intake was not associated with the risk of UCC, however intakes of spirits > 24 g/day were associated with an increased risk of UCC in men (1.38; 95% CI 1.01-1.91) and smokers (1.39; 95% CI 1.01-1.92), compared to moderate intakes. We found no association between alcohol and UCC in women and never smokers. In conclusion, we observed some associations between alcohol and UCC in men and in smokers, possibly because of residual confounding by tobacco smoking.

Insulin-like growth factor I and risk of epithelial invasive ovarian cancer by tumour characteristics: results from the EPIC cohort.

BACKGROUND: Prospective studies on insulin-like growth factor I (IGF-I) and epithelial ovarian cancer (EOC) risk are inconclusive. Data suggest risk associations vary by tumour characteristics. METHODS: We conducted a nested case-control study in the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate IGF-I concentrations and EOC risk by tumour characteristics (n=565 cases). Multivariable conditional logistic regression models were used to estimate associations. RESULTS: We observed no association between IGF-I and EOC overall or by tumour characteristics. CONCLUSIONS: In the largest prospective study to date was no association between IGF-I and EOC risk. Pre-diagnostic serum IGF-I concentrations may not influence EOC risk.

An epidemiologic risk prediction model for ovarian cancer in Europe: the EPIC study.

BACKGROUND: Ovarian cancer has a high case-fatality ratio, largely due to late diagnosis. Epidemiologic risk prediction models could help identify women at increased risk who may benefit from targeted prevention measures, such as screening or chemopreventive agents. METHODS: We built an ovarian cancer risk prediction model with epidemiologic risk factors from 202,206 women in the European Prospective Investigation into Cancer and Nutrition study. RESULTS: Older age at menopause, longer duration of hormone replacement therapy, and higher body mass index were included as increasing ovarian cancer risk, whereas unilateral ovariectomy, longer duration of oral contraceptive use, and higher number of full-term pregnancies were decreasing risk. The discriminatory power (overall concordance index) of this model, as examined with five-fold cross-validation, was 0.64 (95% confidence interval (CI): 0.57, 0.70). The ratio of the expected to observed number of ovarian cancer cases occurring in the first 5 years of follow-up was 0.90 (293 out of 324, 95% CI: 0.81-1.01), in general there was no evidence for miscalibration. CONCLUSION: Our ovarian cancer risk model containing only epidemiological data showed modest discriminatory power for a Western European population. Future studies should consider adding informative biomarkers to possibly improve the predictive ability of the model.

Adherence to the Mediterranean diet and risk of bladder cancer in the EPIC cohort study.

There is growing evidence of the protective role of the Mediterranean diet (MD) on cancer. However, to date no epidemiological study has investigated the influence of the MD on bladder cancer. We evaluated the association between adherence to the MD and risk of urothelial cell bladder cancer (UCC), according to tumor aggressiveness, in the European Prospective Investigation into Cancer and Nutrition (EPIC). The analysis included 477,312 participants, recruited from ten European countries between 1991 and 2000. Information from validated dietary questionnaires was used to develop a relative Mediterranean diet score (rMED), including nine dietary components. Cox regression models were used to assess the effect of the rMED on UCC risk, while adjusting for dietary energy and tobacco smoking of any kind. Stratified analyses were performed by sex, BMI, smoking status, European region and age at diagnosis. During an average follow-up of 11 years, 1,425 participants (70.9% male) were diagnosed with a first primary UCC. There was a negative but non-significant association between a high versus low rMED score and risk of UCC overall (HR: 0.84 [95% CI 0.69, 1.03]) and risk of aggressive (HR: 0.88 [95% CI 0.61, 1.28]) and non-aggressive tumors (HR: 0.78 [95% CI 0.54, 1.14]). Although there was no effect modification in the stratified analyses, there was a significant 34% (p = 0.043) decreased risk of UCC in current smokers with a high rMED score. In EPIC, the MD was not significantly associated with risk of UCC, although we cannot exclude that a MD may reduce risk in current smokers.

Dietary intake of acrylamide and endometrial cancer risk in the European Prospective Investigation into Cancer and Nutrition cohort.

BACKGROUND: Three prospective studies have evaluated the association between dietary acrylamide intake and endometrial cancer (EC) risk with inconsistent results. The objective of this study was to evaluate the association between acrylamide intake and EC risk: for overall EC, for type-I EC, and in never smokers and never users of oral contraceptives (OCs). Smoking is a source of acrylamide, and OC use is a protective factor for EC risk. METHODS: Cox regression was used to estimate hazard ratios (HRs) for the association between acrylamide intake and EC risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Acrylamide intake was estimated from the EU acrylamide monitoring database, which was matched with EPIC questionnaire-based food consumption data. Acrylamide intake was energy adjusted using the residual method. RESULTS: No associations were observed between acrylamide intake and overall EC (n=1382) or type-I EC risk (n=627). We observed increasing relative risks for type-I EC with increasing acrylamide intake among women who both never smoked and were non-users of OCs (HRQ5vsQ1: 1.97, 95% CI: 1.08-3.62; likelihood ratio test (LRT) P-value: 0.01, n=203). CONCLUSIONS: Dietary intake of acrylamide was not associated with overall or type-I EC risk; however, positive associations with type I were observed in women who were both non-users of OCs and never smokers.

Flavonoid and lignan intake in relation to bladder cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

BACKGROUND: There is growing evidence of the protective role of dietary intake of flavonoids and lignans on cancer, but the association with bladder cancer has not been thoroughly investigated in epidemiological studies. We evaluated the association between dietary intakes of total and subclasses of flavonoids and lignans and risk of bladder cancer and its main morphological type, urothelial cell carcinoma (UCC), within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. METHODS: A cohort of 477 312 men and women mostly aged 35-70 years, were recruited in 10 European countries. At baseline, dietary flavonoid and lignan intakes were estimated using centre-specific validated questionnaires and a food composition database based on the Phenol-Explorer, the UK Food Standards Agency and the US Department of Agriculture databases. RESULTS: During an average of 11 years of follow-up, 1575 new cases of primary bladder cancer were identified, of which 1425 were UCC (classified into aggressive (n=430) and non-aggressive (n=413) UCC). No association was found between total flavonoid intake and bladder cancer risk. Among flavonoid subclasses, significant inverse associations with bladder cancer risk were found for intakes of flavonol (hazard ratio comparing fifth with first quintile (HRQ5-Q1) 0.74, 95% confidence interval (CI): 0.61-0.91; P-trend=0.009) and lignans (HRQ5-Q1 0.78, 95% CI: 0.62-0.96; P-trend=0.046). Similar results were observed for overall UCC and aggressive UCC, but not for non-aggressive UCC. CONCLUSIONS: Our study suggests an inverse association between the dietary intakes of flavonols and lignans and risk of bladder cancer, particularly aggressive UCC.

Oral contraceptive use and reproductive factors and risk of ovarian cancer in the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: It is well established that parity and use of oral contraceptives reduce the risk of ovarian cancer, but the associations with other reproductive variables are less clear. METHODS: We examined the associations of oral contraceptive use and reproductive factors with ovarian cancer risk in the European Prospective Investigation into Cancer and Nutrition. Among 327,396 eligible women, 878 developed ovarian cancer over an average of 9 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models stratified by centre and age, and adjusted for smoking status, body mass index, unilateral ovariectomy, simple hysterectomy, menopausal hormone therapy, and mutually adjusted for age at menarche, age at menopause, number of full-term pregnancies and duration of oral contraceptive use. RESULTS: Women who used oral contraceptives for 10 or more years had a significant 45% (HR, 0.55; 95% CI, 0.41-0.75) lower risk compared with users of 1 year or less (P-trend, <0.01). Compared with nulliparous women, parous women had a 29% (HR, 0.71; 95% CI, 0.59-0.87) lower risk, with an 8% reduction in risk for each additional pregnancy. A high age at menopause was associated with a higher risk of ovarian cancer (>52 vs ≤ 45 years: HR, 1.46; 95% CI, 1.06-1.99; P-trend, 0.02). Age at menarche, age at first full-term pregnancy, incomplete pregnancies and breastfeeding were not associated with risk. CONCLUSION: This study shows a strong protective association of oral contraceptives and parity with ovarian cancer risk, a higher risk with a late age at menopause, and no association with other reproductive factors.

Fruits and vegetables consumption and the risk of histological subtypes of lung cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC).

OBJECTIVE: To examine the association between fruit and vegetable consumption and risk of different histological subtypes of lung cancer among participants of the European Prospective Investigation into Cancer and Nutrition study. METHODS: Multivariable Cox proportional hazard models were used to analyze the data. A calibration study in a subsample was used to reduce dietary measurement errors. RESULTS: During a mean follow-up of 8.7 years, 1,830 incident cases of lung cancer (574 adenocarcinoma, 286 small cell, 137 large cell, 363 squamous cell, 470 other histologies) were identified. In line with our previous conclusions, we found that after calibration a 100 g/day increase in fruit and vegetables consumption was associated with a reduced lung cancer risk (HR 0.94; 95% CI 0.89-0.99). This was also seen among current smokers (HR 0.93; 95% CI 0.90-0.97). Risks of squamous cell carcinomas in current smokers were reduced for an increase of 100 g/day of fruit and vegetables combined (HR 0.85; 95% CI 0.76-0.94), while no clear effects were seen for the other histological subtypes. CONCLUSION: We observed inverse associations between the consumption of vegetables and fruits and risk of lung cancer without a clear effect on specific histological subtypes of lung cancer. In current smokers, consumption of vegetables and fruits may reduce lung cancer risk, in particular the risk of squamous cell carcinomas.

Moderate physical activity in relation to mammographic patterns.

High-risk mammographic patterns may be used as a surrogate end point for breast cancer in etiologic research as well as in prevention studies. Physical activity may be one of the few modifiable risk factors for breast cancer. We examined the relationship between physical activity and mammographic patterns among 2720 Norwegian women, ages 40-56 years, who participated in both the Second and Third Tromsø studies. Epidemiologic data were obtained through questionnaires. Two questions from the Second Tromsø study and five questions from the Third elicited information on physical activity. The mammograms were categorized into five groups based on anatomical-mammographic correlations. For analysis, patterns I through III were combined into a low-risk group and patterns IV and V into a high-risk group. Odds ratios that were adjusted for age, education, menopausal status, body mass index, parity, age at menarche, oral contraceptive use, and alcohol intake, with 95% confidence intervals, were estimated using logistic regression. Women who reported moderate physical activity, i.e., more than 2 h/week, were 20% less likely (odds ratio, 0.8; 95% confidence interval, 0.6-1.1) to have high-risk mammographic patterns compared with those who reported being inactive. This relationship remains consistent when stratified by menopausal status, parity, and tertiles of body mass index. However, all of the associations between various measures of physical activity and high-risk patterns found in this study are weak with confidence intervals that include 1.0. Thus, chance is a reasonable explanation for the weak associations found. The relationship between physical activity and high-risk patterns should be examined further as a means to explore the biologic mechanisms relating physical activity to breast cancer risk.

Reversal of gonadotropin-releasing hormone agonist induced reductions in mammographic densities on stopping treatment.

Previously, we described the reduction in mammographic densities that occurred in premenopausal women after 12 months on a hormonal regimen designed to be chemopreventive for breast (and ovarian) cancer consisting of a gonadotropin-releasing hormone agonist (GnRHA) plus low-dose add-back estrogen-progestin. We sought to determine whether the density reduction persisted with continuation of the regimen for 24 months, and, if so, whether the densities would return to baseline after the regimen was discontinued. Twenty-one women, 27-40 years of age, with a 5-fold greater than normal risk of breast cancer, were randomly assigned in a 2:1 ratio to the treatment group (14 women) and to a control group (7 women). The percentage of mammographic densities, calculated as the proportion of the breast area on the mammogram containing densities, were assessed blindly using a computer-based threshold method at baseline, after 12 and 24 months of treatment, and at between 6 and 12 months after treatment was stopped. The previously described percentage of mammographic density reductions of 9.7% (P = 0.012) after 12 months of treatment were increased slightly to 11.4% (P = 0.010) after 24 months of treatment, but the additional change was not statistically significant. Ten of 11 treated women assessed at 24 months had reduced percentages of mammographic densities compared with baseline. Six to 12 months after completion of treatment, the mean percentage of mammographic density in the treated group was no different from that at baseline (mean decline of 2.0%; P = 0.73). The women in the control group had no statistically significant changes in densities over the period of the study. Reductions in mammographic densities engendered by the GnRHA plus a low-dose add-back estrogen-progestin regimen persist as long as the women receive treatment. The densities return to baseline when the women resume normal menstrual cycles. These results confirm that mammographic densities are influenced by ovarian function. Improved efficacy of mammographic screening is to be expected as long as a woman continues on such a regimen. Whether such a regimen is chemopreventive for breast cancer remains to be established, but the recent report on a randomized trial of use of GnRHA alone in premenopausal breast cancer cases showing a marked reduction in incidence of contralateral disease provides strong support for the hypothesis.

Oral contraceptive use and mammographic patterns.

High-risk mammographic patterns represent an increased risk of contracting breast cancer and may be used as a surrogate endpoint for the disease. We examined the relationship between oral contraceptive (OC) use and mammographic patterns among 3218 Norwegian women, aged 40-56 years. Information on ever OC use, duration, and age of first OC use and other epidemiological data were obtained through questionnaires. The mammograms were categorized into five groups. Patterns I-III were combined into a low-risk group and patterns IV and V into a high-risk group. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression and adjusted for age, menopausal status, parity, age at first birth, and body mass index. Women who reported ever having used OCs were 20% more likely (OR 1.27, 95% CI 1.0-1.6) to have high-risk mammographic patterns compared with those reporting never having used OCs. There was no dose response between different measures of OC use and high-risk patterns. Among nulliparous women, ever OC users were four times more likely (OR 4.65, 95% CI 2.1-10.3) to have high-risk patterns compared with never users. Our findings suggest that, especially among nulliparous women, ever OC use may exert its effect on breast cancer risk through changes in breast tissue, which can be observed on a mammogram.

The Tabár classification of mammographic parenchymal patterns.

The purpose of this study was to describe one method of classification, based on anatomic-mammographic correlations, developed by Tabár. We also wanted to examine how the mammograms categorized as low- and high-risk according to Tabár and Wolfe criteria related to each other and to three selected risk factors for breast cancer. The study materials are based on questionnaires and mammograms from 3,640 Norwegian women, aged 40-56 years, participating in the third Tromsö study. The mammograms were categorized into five groups. Line drawings and their pathologic correlates of the five patterns are described in detail. The Tabár classification is based on anatomic-mammographic correlations, following three-dimensional (thick slice technique) histopathologic-mammographic comparisons, rather than simple pattern reading (Wolfe classification). For analysis patterns I-III (Tabár) and N1 and P1 (Wolfe) were grouped into low-risk groups and patterns IV and V (Tabár) and P2 and DY Wolfe) into high-risk groups. The overall agreement on high-risk versus low risk for the two classifications was 54% with a kappa-value of 0.22. The study displays that the strength of association between high-risk mammographic patterns and the three selected risk factors parity, number of children and age at first birth is of greater magnitude when the Tabár instead of the Wolfe classification is applied. More patients are needed to compare the classification directly with the risk of cancer. This study indicates that further development of the classification of mammograms may increase the usefulness of mammographic patterns in research and clinical practice.

Rheumatoid arthritis: a commonly misused diagnosis by the general population.

The purpose of this study was to explore what a young general population include when they answer questions concerning the diagnosis rheumatoid arthritis (RA). Altogether 14,420 subjects answered questionnaires concerning disease history, living habits and musculoskeletal pain. They were also asked specifically if they, or any close relative, had RA. One hundred and sixteen (1.6%) men and 115 (1.6%) women reported that they had the disease. Altogether 14 (12%) men and 23 (20%) women of those answering "yes" to the RA question, were found to have the disease verified according to their hospital records. Fifty-five (25%) of the subjects who reported to have RA, were classified in their hospital records as having other defined rheumatic diseases. Our study indicates that when the general population refers to the diagnosis of RA, they include most defined rheumatic diseases as well as unspecified arthralgia. We find it interesting that such a substantial number of young people report they have this serious disease. We therefore recommend that other measures should be used or used in addition to mailed questionnaires when exploring the prevalence of RA.

Clinical impact of atypical squamous cells of undetermined significance. A cytohistologic comparison.

OBJECTIVE: To assess the percentage of squamous intraepithelial lesions (SILs) in the atypical squamous cells of undetermined significance (ASCUS) cytologic diagnosis. STUDY DESIGN: From January 1994 to December 1995, 421 cervical Pap smears with a diagnosis of ASCUS were followed with cervical biopsies within three months. The ASCUS cytologic diagnosis was correlated with the histologic findings and stratified according to age group, previous abnormal history and cell type of ASCUS (squamoid vs. metaplastic). RESULTS: Histologic diagnosis showed that of ASCUS diagnoses, 13% were normal, 34% were reactive, 4.8% were atypical, 43% were low grade SIL, 4% were high grade SIL, 1% were carcinoma in situ, and none were invasive lesions. The patients in the youngest group, up to 25 years, demonstrated the highest percentage of SIL. Patients with a previous abnormal gynecologic history showed a higher percentage of SIL than those without an abnormal history. SILs were observed in 51.5% of squamoid ASCUS and 36.5% of metaplastic ASCUS. CONCLUSION: Forty-eight percent of females having an ASCUS diagnosis on Pap smears had SIL and thus a preneoplastic lesion. The highest percentage of SIL was found in females 25 years and younger. Our findings suggest that an ASCUS diagnosis warrants ongoing follow-up.

Body mass index, waist circumference and waist-hip ratio and serum levels of IGF-I and IGFBP-3 in European women.

OBJECTIVE: To examine the relationship between body mass index (BMI) and waist-hip ratio (WHR) with serum levels of insulin-like growth factor-I (IGF-I), and its binding protein (IGFBP)-3. DESIGN: Cross-sectional study on 2139 women participating in a case-control study on breast cancer and endogenous hormones. Data on lifestyle and reproductive factors were collected by means of questionnaires. Body height, weight, waist and hip circumferences were measured. Serum levels of IGF-I and insulin-like binding protein (IGFBP)-3 were measured by enzyme-linked immunosorbent assays. Adjusted mean levels of IGF-I and IGFBP-3 across quintiles of BMI, waist circumference, and WHR were calculated by linear regression. Results were adjusted for potential confounders associated with IGF-I and IGFBP-3. RESULTS: Adjusted mean serum IGF-I values were lower in women with BMI<22.5 kg/m(2) or BMI>29.2 kg/m(2) compared to women with BMI within this range (P(heterogeneity)<0.0001, P(trend)=0.35). Insulin-like growth factor-I was not related to WHR after adjustment for BMI. IGF-binding protein-3 was linearly positively related to waist and WHR after mutual adjustment. The molar ratio IGF-I/IGFBP-3 had a non-linear relation with BMI and a linear inverse relationship with WHR (P (trend)=0.005). CONCLUSIONS: Our data confirm the nonlinear relationship of circulating IGF-I to total adiposity in women. Serum IGFBP-3 was positively related to central adiposity. These suggest that bioavailable IGF-I levels could be lower in obese compared to non-obese women and inversely related to central adiposity.

Skin symptoms in the seafood-processing industry in north Norway.

A survey of occupational skin problems, based on a questionnaire, was carried out among 883 workers in different types of seafood-processing industries in northern Norway. The prevalence of dry skin, itching, rash/eczema, chapped skin and chronic sores was significantly higher among production workers (55.6%) in the white fish-, shrimp- and salmon-processing industries, compared to administrative workers in the same industries (27.5%). Among production workers, there was a significantly higher prevalence of skin symptoms among females (60.2%) compared to males (50.1%). A strong sex division of work tasks rather than sex itself may explain this. There was no sex difference among administrative workers. Several risk factors for skin symptoms to occur are indicated. The workers are exposed to raw materials and a mixture of water and juice from the fish or shrimp, salt, detergents and disinfectants. Gloves may also cause skin problems. Major risk factors believed to cause skin symptoms were contact with raw materials, fish juice, water and gloves. The results also indicate that skin symptoms are of moderate severity and seldom interfere with working capacity.

[Vasectomy. Subjective and objective reactions]. / Vasektomi. Subjektive og objektive reaksjoner.

PIP: The 1st follow-up study on vasectomy ever conducted in Norway involved 22 men who were patients at the Urological Clinic in Troms during a 6 month period in 1980. The average age at time of the procedure was 40.8, with the youngest 29 and the oldest 51. The men were all married or living with a woman in a longterm relationship. The goal of the study was to determine subjective and objective reactions to their vasectomies. An effort was made to ascertain: 1) the reasons for the choice of vasectomy as a form of contraception, 2) how long it took for azoospermia (no sperm cells) to occur following the operation, 3) if there were any postoperative complications, 4) presence of sperm antibodies in blood, 5) if any hormonal changes occurred, 6) if any changes appeared in one's sex life. The men were 1st given a sperm-count test 4 weeks after the operation, and post-operative blood tests were taken 6 months after the sterilization. Routine hormone analyses were conducted at the hormone laboratory in Oslo. Questionnaires concerning motivations for the surgery, resulting complications, sexual life, etc. were sent out around 6 months after the operation. Results showed that all patients had azoospermia after 12 weeks. Around half had azoospermia after only 4 weeks. 20/22 subjects reported not having to take any sick leave from work after the operation, except for the day of the operation. Neither of the 2 who did have to take sick leave were away from work for more than 3 days. There was no significant difference in hormone levels before and after the vasectomies. 14 patients had no complaints of postoperative discomfort. 5 had stinging for around a week, and 3 had inflammation. The main reason for selecting vasectomy as a contraceptive method for 11 of 18 men was that it was "the surest method." The same proportion stated having considered with their wives that sterilization of 1 partner was the desired method, and that the procedure was simpler for the man. 3 subjects reported frequency of intercourse had increased after their vasectomy, while the other 15 who filled out the questionnaire believed they had experienced no change. None of the men thought they felt any decrease in sexual drive or potency, while 1 said he thought these had increased. None of the men thought the operation had had any negative effects on their relationship with their partner. Results of the study confirmed with others in indicating that high motivation and availability of accurate information are important factors in obtaining positive subjective feelings after vasectomy.^ieng

Cancer anxiety and attitudes toward mammography among screening attenders, nonattenders, and women never invited.

A mailed questionnaire survey was conducted among the following groups: 179 women who screened false positive at a free mammography screening; a random sample of 250 women who screened negative; 670 nonattenders of the screening; and a random population sample of 250 women who lived in another city and were not invited, but were otherwise comparable. The most frequently reported reason for nonattendance was not having the opportunity. Furthermore, only 18% of the nonattenders reported anxiety about breast cancer compared with 33% of the population sample (P less than .05). Ninety-nine percent of the women who attended indicated a positive attitude toward mammography that had not been adversely affected by screening experiences.

Response rate according to title and length of questionnaire.

The purpose of this study was to investigate how response rates to a postal questionnaire are affected by title and length of the survey instrument. Five questionnaires, which differed according to title and length, were designed. Each questionnaire was mailed to a random sample of one thousand Norwegian women aged, 35-49 years. A total of 3,106 questionnaires were returned (62.1%). The highest response rate (70.2%) was achieved by a two-page questionnaire entitled "Women and Cancer". An otherwise identical questionnaire entitled "Oral Contraceptives and Cancer" had a response rate of 60.7%. Questionnaires entitled "Women and Cancer" with a length of four and six pages had a response rate of 62.8% and 63.3%, respectively. The four page questionnaire entitled "Women, Lifestyle and Health" had the lowest response rate of 57.1%. This study shows that in a general population of Norwegian women the title of a postal questionnaire influences the response rate. The results indicate that although the shortest questionnaire had the highest response rate, the most extensive survey instrument did not have the lowest response rate. The distribution of risk factors for breast cancer did not vary according to response rate or design of questionnaire. The overall findings of this study suggest that the benefits from the increased information obtained from extensive postal questionnaires out-weighs a potential non-response bias due to a somewhat lower response rate.