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A case-control study of reproductive factors and cancer of the ovary was conducted during 1989-1992 in metropolitan Toronto and nearby areas of Southern Ontario, Canada. In total, 450 women aged 35-79 years with histologically verified new primary epithelial ovarian cancers were interviewed concerning their reproductive histories. Over the same time period, 564 randomly selected population controls, frequency-matched to the cases according to three 15-year age groups, were also interviewed. Continuous unconditional logistic regression methods were used for analysis. It was found that childbearing and use of oral contraceptives were associated with significant decreasing trends in risk of ovarian cancer; the respective odds ratios were 0.78 for each full-term pregnancy (p < 10(-8)) and 0.92 for each year of use (p < 10(-6)). Hysterectomy was also associated with reduced risk, even after more than 20 years. Among parous women, infertility did not appear to affect risk; for nulliparous women, some evidence of increased risk was present, although fertility problems were reported by only a small fraction of nulliparae. It is suggested that the relatively lower parity of cases as compared with controls may be due to voluntary choices for having fewer children.

Data are presented from an interview case-control study (583 cases and 608 controls), performed in southern Ontario, Canada, from October 1984 to September 1986, on the association of cutaneous malignant melanoma with exposure to fluorescent light. Males showed a significant trend with cumulative years of occupational exposure and with various indices of exposure to domestic fluorescent light. The risk was more pronounced for lesions on the arms and for superficial spreading melanomas. There was no consistent association in females. These effects were similar when adjusted for other major risk factors for melanoma, including the amount of time spent outdoors occupationally. Comparisons of melanoma cases interviewed before or after diagnosis revealed no evidence of rumination bias. Comparisons of sample data from the same cases and controls by interview and mail questionnaire showed reasonable levels of reliability with no evidence of recall bias. A small sample of subjects was also selected for exposure validation with employers; this revealed very accurate recall of occupational exposure. On the basis of these results, previous epidemiologic studies, and clinical and animal evidence, the authors conclude that fluorescent light exposure remains a potential risk factor for melanoma.

Data are presented from a large case-control study (583 cases, 608 controls) to estimate the association of melanoma with the use of sunbeds and sunlamps. Odds ratios of 1.88 and 1.45 were found for ever having used a sunbed or sunlamp in males and females, respectively, which was statistically significant in males and of borderline significance in females. These effects persisted when adjustments were made for age and a variety of potential confounders. The effect was slightly stronger for lentigo maligna and for lesions of the face, head, neck, and arms. The risk was greater and significant for both sexes for domestic use of sunbeds/sunlamps, and increased with duration and amount of use. A comparison of 43 cases interviewed before a diagnosis of melanoma had been made with the other 540 cases suggests that recall bias was not responsible for the association. The authors conclude that use of artificial tanning devices appears to be a risk factor for melanoma.

The association between coffee consumption and bladder cancer is investigated in a population-based case-control study carried out in Connecticut during 1978-1979. Measures of coffee consumption employed include total weekly cups, years of consumption, and more than seven cups per week, in addition to use frequencies of specific coffee types. After adjustment for age and cigarette smoking, a significant elevation in risk for consuming more than seven cups weekly was found for males (odds ratio = 1.5) but not for females (odds ratio = 1.0); there was also some evidence of a dose-response relationship in males. Among nonsmokers of both sexes combined, the odds ratio for more than seven cups per week was 1.9. Male smokers showed age- and smoking-adjusted odds ratios for coffee similar to those of male nonsmokers. Female smokers had a decreased risk for bladder cancer associated with increased coffee consumption which reflects the substantially lowered risk among older (65 years and over) smoking women who may constitute a selected resistant group; odds ratios among younger female smokers were close to 1.0. Males also showed elevated risks associated with consumption of regular (non-decaffeinated) and ground (noninstant) coffees. No relationship with duration of consumption was found.

The incidence of cancer of the uterine corpus diagnosed in the localized 1964 and 1969. During the next six years, however, it increased substantially, reaching a peak in 1975, followed by an irregular decline through 1979. Women aged 45-64 years showed both the largest increase and the sharpest decline. The incidence of tumors diagnosed with regional or distant spread has been rising slightly but consistently through the period 1970-1979; this upward trend is statistically significant (p less than 0.01). Rates corrected for hysterectomized women not truly at risk are 40-50% higher than uncorrected rates but trends are the same. Explanations which are considered are changes in diagnostic practices and changes in risk factor prevalence. The use of noncontraceptive oral estrogens, a well documented risk factor for endometrial cancer, increased between 1964 and 1975 and then declined sharply through 1979 in the United States. The importance of these compounds in explaining the observed incidence trends is considered in terms of the major time- and stage-specific features of the exogenous estrogen-endometrial cancer association reported in the case-control studies.

A population-based case-control study of histologically confirmed endometrial neoplasia was conducted in Toronto, Canada, between 1977 and 1978. Pathologic slide review resulted in classification of patients to diagnostic categories of endometrial carcinoma, endometrial carcinoma in situ, and endometrial hyperplasia. This report concerns the subset of patients classified as having adenomatous endometrial hyperplasia. Two age-matched neighborhood controls were selected for each case, and analyses included only those case-control sets in which the case and at least one control were concordant on menopausal status. Among postmenopausal women (87 cases and 151 controls), noncontraceptive estrogen use was a statistically significant risk factor (adjusted odds ratio (OR) = 6.7), as was heavy body weight relative to height (Quetelet index) (adjusted OR = 3.2). Long-term (5+ years) estrogen use conferred an estimated relative risk of more than 20, but use of oral contraceptives did not alter risk significantly. Among premenopausal women (62 cases and 97 controls), a high Quetelet index appeared to be a significant protective factor, even when adjusted for oral contraceptive use (adjusted OR = 0.2). While oral contraceptive use was not associated with a change in risk, long duration of use was highly, but statistically not significantly, protective against hyperplasia. The data for pre- and postmenopausal women indicate that both endogenous and exogenous estrogen exposure are important factors in the etiology of adenomatous endometrial hyperplasia.