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Biomedical subjects

H A Risch

Publications and source records attributed to H A Risch.

At least 37 records · Page 2Linked to original sources
PubMed1996

Differences in risk factors for epithelial ovarian cancer by histologic type. Results of a case-control study.

A case-control study of associations between dietary and 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 history and dietary practices. 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 the risk of epithelial ovarian cancer of all principal histologic types except mucinous tumors. For each full-term pregnancy, the odds ratio was 0.76 (95% confidence interval (CI) 0.69-0.85) for nonmucinous tumors and 1.03 (95% CI 0.88-1.21) for mucinous tumors; for each year of oral contraceptive use, the odds ratio was 0.89 (95% CI 0.85-0.93) for nonmucinous tumors and 0.98 (95% CI 0.93-1.04) for mucinous tumors (p = 0.00051 and p = 0.0040, respectively, for the difference in odds ratios between mucinous and nonmucinous tumors). Saturated fat intake also appeared to convey greater increased risk for women with mucinous tumors than for women with neoplasms of other histologic types (p = 0.029). Among women with nonmucinous tumors, increasing trends in risk of invasive serous cancer (p = 0.018), and particularly endometrioid cancer (p = 0.0041), were seen with use of noncontraceptive estrogens. Otherwise, borderline-malignant neoplasms seemed to have a similar spectrum of risk factor associations as invasive cancers. On the basis of this study and a number of others, the authors suggest that mucinous ovarian tumors may be etiologically unrelated to other types of epithelial tumors, and thus should be considered separately in studies of ovarian cancer.

Adult↗
PubMed1996

Estrogen replacement therapy and risk of epithelial ovarian cancer.

Estrogen replacement therapy (ERT), in common use among menopausal women, has been inconsistently related to risk of ovarian cancer. Part of the inconsistency may be due to differences in risk according to tumor histology. We therefore compared, within histologic groups, 367 cases of invasive epithelial ovarian cancer to 564 population controls on history of ERT practices. In multivariate logistic regression analyses adjusted for age, parity, oral-contraceptive usage, and other factors, the relative odds of nonmucinous ovarian cancer increased by 5.1% for each year of ERT use [i.e., adjusted odds ratio, 1.051; 95% confidence interval (CI), 1.01-1.09, as a multiplicative factor for each year of use]. In particular, compared to never use, women who employed ERT for a total of 5 years or longer had a relative odds of 2.03 (95% CI, 1.04-3.97) of having a serous carcinoma and 2.81 (95% CI, 1.15-6.89) of having an endometrioid carcinoma. Mucinous tumors were not associated with use. ERT usage may contribute to the development of nonmucinous types of ovarian cancer, and additional histology-specific analysis of this association in other studies is warranted.

Adenocarcinoma, Mucinous↗
PubMed1994

Hereditary and familial ovarian cancer in southern Ontario.

BACKGROUND: Hereditary ovarian cancer may be site specific or may appear in combination with breast cancer or other cancers in a family. The most common hereditary form is the breast-ovarian cancer syndrome. It is estimated that in 100% of these families, there is linkage to a cancer susceptibility gene on chromosome 17q, BRCA1. METHODS: A positive family history of breast or ovarian cancer was reported for 71 of 450 unselected cases of ovarian cancer identified in Southern Ontario. Detailed pedigrees were completed by telephone interview for 48 of the 71 subjects. RESULTS: Nine families were identified with five or more cases of breast or ovarian cancer, 14 families with four cases of cancer, and eight families with three cases. Breast cancer appeared in 80% of the ovarian cancer families. There were 81 healthy first-degree female relatives of the cancer cases considered to be at high risk for ovarian cancer. CONCLUSIONS: It is feasible to use a simple questionnaire on all incident cases of ovarian cancer in a population to identify families with potential hereditary breast-ovarian cancer. Two point nine percent to 6.9% of cases of ovarian cancer appear to be inherited; the majority of the families also will have an excess number of cases of breast cancer.

Adult↗
PubMed1994

Parity, contraception, infertility, and the risk of epithelial ovarian cancer.

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.

Adult↗
PubMed1994

Dietary fat intake and risk of epithelial ovarian cancer.

BACKGROUND: Evidence exists that dietary fat may be a contributory factor in the development of hormone-related cancers such as ovarian cancer. Previous studies have demonstrated significantly higher circulating-estrogen levels among nonvegetarian women than among vegetarian women; the increase correlated directly with consumption of saturated fat. However, the contribution that dietary fat plays in the development of hormone-related cancers remains unresolved. PURPOSE: Our purpose was to evaluate whether saturated fat intake increases the risk of ovarian cancer development. METHODS: Population-based sampling was used to acquire cases and controls over a 3-year period from the study area, which included the highly populated region surrounding the western end of Lake Ontario, Canada. From the Ontario Cancer Registry, all histologically confirmed, primary malignant or borderline malignant epithelial ovarian tumors first diagnosed from November 1989 through October 1992 among study-area residents aged 35-79 years were determined. In total, 631 eligible case subjects were identified, of whom 450 (71.3%) were interviewed concerning reproduction and diet; 564 randomly selected population control subjects were similarly interviewed. From the quantitative diet-history information, average daily intakes of macronutrients and micronutrients were calculated. Unconditional continuous logistic regression methods were used for analysis, with adjustment for age at interview, number of full-term pregnancies, years of oral contraceptive use, and total daily caloric intake. RESULTS: Saturated fat consumption was associated with increasing risk of ovarian cancer (odds ratio [OR] = 1.20 for each 10 g/day of intake; 95% confidence interval [CI] = 1.03-1.40; one-sided P = .0082). No relationship was seen with intake of unsaturated fats. Egg consumption also appeared related to increased risk (OR = 1.42 for each 100 mg of egg cholesterol per day; 95% CI = 1.18-1.72; two-sided P = .0002), though this association may have resulted from disease-related changes in the dietary practices of case subjects prior to diagnosis. Consumption of vegetable fiber (but not fruit or cereal fiber) was associated with decreased risk (OR = 0.63 for each 10 g/day; 95% CI = 0.49-0.80; two-sided P = .0001). All three nutrients (saturated fat, egg cholesterol, and vegetable fiber) remained statistically significant when included in the same regression model. CONCLUSION: Diet may contribute to risk of ovarian cancer development. IMPLICATION: If confirmed in further studies, this association may allow women to appreciably lower their risk of ovarian cancer through dietary modifications: reducing the intake of saturated fats and eating more vegetables.

Adult↗
PubMed1994

Menopausal hormone usage and breast cancer in Saskatchewan: a record-linkage cohort study.

The association between the occurrence of carcinoma of the breast and previous usage of menopausal estrogens, progestins, and oral contraceptives is examined in a record-linkage study using the Saskatchewan Health Prescription-Drug-Plan Database. Saskatchewan Health is a governmental agency that funds publicly insured health care for essentially all residents of the province. For this study, all women aged 43-49 years in 1976 resident in Saskatchewan were identified from the Saskatchewan Health master registration file. These women were linked by registration beneficiary number to the Drug-Plan Database for the period from January 1976 to June 1987 and to the Provincial Cancer Registry Database for the period from March 1960 to December 1990. The fact and date of death or emigration from the province were obtained through the annual updates of the health plan. Of the 33,003 women initially in the cohort, 213 had a breast cancer diagnosed before 1976 and were omitted from this analysis. Between 1976 and 1990, 742 new primary breast cancer cases occurred. Women taking estrogens unopposed by progestins had an elevated risk of breast cancer, the risk increasing by 7% (relative risk = 1.072, 95% confidence interval 1.02-1.13; p = 0.008) for each 252 tablets used (approximately 1 year of use). Usage of estrogens opposed by progestins showed no association with risk (p = 0.48). Women taking oral contraceptives during this follow-up period also had a higher risk, increasing by 14% (relative risk = 1.144, 95% confidence interval 1.05-1.24; p = 0.002) for every 252 tablets used. These 1-year risk elevations are small but become appreciable at longer durations. For example, at 5 years of unopposed estrogen use, the relative risk is 1.42; for 5 years of oral contraceptive use, it is 1.96.

Adult↗
PubMed1994

Dietary lactose intake, lactose intolerance, and the risk of epithelial ovarian cancer in southern Ontario (Canada).

A case-control study of dietary factors and cancer of the ovary was conducted during 1989-92 in metropolitan Toronto and surrounding areas of southern Ontario, Canada. Four hundred and fifty women aged 35-79 years, with newly diagnosed, histologically verified, primary epithelial ovarian-cancer were interviewed concerning reproduction and diet. Over the same period, 564 randomly-selected population controls, frequency-matched to the cases within three 15-year age groups, also were interviewed. From information obtained by quantitative diet history, average daily macro- and micronutrient intake values were calculated through use of the United States Department of Agriculture Food Composition Databank, which was extended and modified for Canadian items and recipes. Analysis was performed with continuous, unconditional logistic-regression methods, adjusting for age at interview, number of full-term pregnancies, total duration of oral contraceptive use, and total daily caloric intake. Neither reported history of lactose intolerance, nor average daily consumption of lactose or free galactose, were found to be associated with risk of ovarian cancer. Lactose intake or intolerance did not appear to modify the protective effects of parity and oral contraceptive use. Nevertheless, other studies suggest that ovarian galactose metabolism still may have a relationship with risk of ovarian cancer, though more evidence is needed.

Adult↗
PubMed1993

Are female smokers at higher risk for lung cancer than male smokers? A case-control analysis by histologic type.

A case-control study of male-female differences in cigarette smoking and lung cancer was conducted during 1981-1985 in Toronto, St. Catharine's, and Niagara Falls, Ontario, Canada. In total, 442 female and 403 male histologically verified cancer cases were individually matched by age and area of residence to each other and to 410 female and 362 male randomly selected population controls. Subjects were interviewed concerning their exposures to various life-style factors, and in particular, they received detailed questioning regarding their lifelong histories of usage of tobacco products. It was found that, for both sexes, a greatly elevated risk of developing lung cancer was associated with cigarette consumption, increasing with pack-years of cigarettes smoked and declining with duration of time since quitting smoking. Furthermore, the association was significantly (p = 0.010) and appreciably stronger for females than for males. At a history of 40 pack-years relative to lifelong nonsmoking, the odds ratio for women was 27.9 (95% confidence interval (CI) 14.9-52.0) and that for men was 9.60 (95% CI 5.64-16.3). Higher odds ratios for females were also seen within each of the major histologic groupings. Thus, the higher elevated risk of lung cancer currently observed in other studies for female ever smokers compared with male ever smokers, while possibly attributable in part to greater smoking cessation among males, may be due to higher susceptibility among females.

Adenocarcinoma↗
PubMed1990

Dietary factors and risk of lung cancer: results from a case-control study, Toronto, 1981-1985.

Associations between dietary factors and risk of lung cancer are reported from a study of 839 cases and 772 population-based controls interviewed in metropolitan Toronto between 1981 and 1985. Increased consumption of vegetables is associated with a decreased relative risk of 0.60 (95% confidence limits = 0.40 to 0.88) for those in the highest compared with the lowest quartile. Cholesterol intake is associated with increased risk, but this is restricted to those in the highest quartile for whom the relative risk is 1.58 (95% confidence limits = 1.05 to 2.38) compared with those in the lowest quartile. The results of this study suggest that dietary factors may affect the risk of lung cancer, but identification of the specific constituents involved will require further research.

Adult↗
PubMed1989

Mortality from breast cancer after irradiation during fluoroscopic examinations in patients being treated for tuberculosis.

The increasing use of mammography to screen asymptomatic women makes it important to know the risk of breast cancer associated with exposure to low levels of ionizing radiation. We examined the mortality from breast cancer in a cohort of 31,710 women who had been treated for tuberculosis at Canadian sanatoriums between 1930 and 1952. A substantial proportion (26.4 percent) had received radiation doses to the breast of 10 cGy or more from repeated fluoroscopic examinations during therapeutic pneumothoraxes. Women exposed to greater than or equal to 10 cGy of radiation had a relative risk of death from breast cancer of 1.36, as compared with those exposed to less than 10 cGy (95 percent confidence interval, 1.11 to 1.67; P = 0.001). The data were most consistent with a linear dose-response relation. The risk was greatest among women who had been exposed to radiation when they were between 10 and 14 years of age; they had a relative risk of 4.5 per gray, and an additive risk of 6.1 per 10(4) person-years per gray. With increasing age at first exposure, there was substantially less excess risk, and the radiation effect appeared to peak approximately 25 to 34 years after the first exposure. Our additive model for lifetime risk predicts that exposure to 1 cGy at the age of 40 increases the number of deaths from breast cancer by 42 per million women. We conclude that the risk of breast cancer associated with radiation decreases sharply with increasing age at exposure and that even a small benefit to women of screening mammography would outweigh any possible risk of radiation-induced breast cancer.

Adolescent↗
PubMed1989

Risk of bladder cancer by source and type of tobacco exposure: a case-control study.

The association between tobacco use and risk of bladder cancer was investigated in a population-based case-control study conducted in Alberta and south-central Ontario, Canada, between 1979 and 1982. In all, 826 histologically-confirmed cancer cases and 792 randomly selected controls, individually matched to cases for age, sex, and area of residence, were recruited into the study. Compared to those who had never smoked cigarettes, males and females who had ever smoked cigarettes had a statistically highly significant 2-fold increase in risk of bladder cancer; for ex-smokers, the risk was intermediate between that for current smokers and never-smokers. There was a dose-dependent increase in risk of bladder cancer with total lifetime cigarette consumption, of similar magnitude for males and females. In males, risk increased with self-reported degree of inhalation in ex-smokers and in current smokers (statistically significant trend), while in females there was no association in current smokers, and a statistically significant inverse association in ex-smokers. Overall, risks of bladder cancer associated with lifetime consumption of plain and filter cigarettes were similar, and there was little evidence to suggest that switching from plain to filter cigarettes was beneficial. Neither passive smoking nor other forms of tobacco consumption (pipes, cigars, chewing tobacco, or snuff) were associated with altered risk of bladder cancer. The population attributable risk for cigarette smoking was about 47% in males and about 33% in females.

Adult↗
PubMed1989

An exploratory case-control study of brain tumors in children.

An exploratory case-control study of childhood brain tumors was conducted in southern Ontario between 1977 and 1983, on 74 cases and 138 age- and sex-matched population controls. A significantly elevated risk (perhaps due to early case symptoms) was seen for skull X-rays at least 5 years prior to diagnosis, and for head or neck injuries which required medical attention. However, no evidence of an increased risk appeared for exposure to sick pets or to pesticides, maternal or paternal history of smoking, and various birth characteristics or antenatal exposure of the child, though these have previously been reported to be associated with childhood brain tumors. With respect to the hypothesis that N-nitroso compounds may be involved in the etiology of childhood brain tumors, most exposures of this type were not associated with risk, though a significant positive association was seen for consumption of beer by the mother during pregnancy, and a significant negative association was seen with consumption of fruit juice by the child. Other findings in the present study include an association with developmental problems relating to height and weight and with certain socioeconomic characteristics of the mother. Further investigation of these results in future studies is warranted.

Adolescent↗
PubMed1988

Lymphocyte micronuclei and sister chromatid exchanges among Canadian federal laboratory employees.

Blood lymphocytes from 59 federally employed Canadian laboratory workers, 137 nearby office employees, and 11 workers with a mixed employment history were examined for the presence of sister-chromatid exchanges and micronuclei. These laboratory workers were exposed routinely to a host of organic solvents and had previously voiced complaints regarding the adequacy of the ventilation system in their building. Overall, no relationship between laboratory work and either cytogenetic endpoint was observed. The two tests were only weakly correlated, but in a multivariate analysis, both were associated with recent and past smoking. Within-person variation was measured for the sister-chromatid exchange assay, and it and other possible sources of variation are discussed.

Abortion, Spontaneous↗
PubMed1988

An application of capture-recapture methods to the estimation of completeness of cancer registration.

Completeness of cancer registration has not been consistently ascertained across different registries. This report describes how capture-recapture methods have been used to estimate completeness at the Ontario Cancer Registry. The method was applied in two fashions; first, using three data sources in a modeling approach: and second, using two data sources and standard, simple capture-recapture methods. The modeling approach is more flexible, since several variables that influence cancer registration can be considered and can be used to identify reporting patterns of different data sources. In the present analysis, estimates of completeness of the registry as a whole were remarkably similar using either two or three data sources, and site-specific comparisons differed by at most 7%. Because of the advantages of capture-recapture methods-estimation of level of completeness, possible comparability of estimates across different registries, and versatility to consider other determinants of cancer registration-a plea for greater use of these methods in cancer registration is made.

Data Collection↗
PubMed1988

Dietary factors and the incidence of cancer of the urinary bladder.

A case-control study of diet and bladder cancer was conducted during 1979-1982 in Edmonton, Calgary, Toronto, and Kingston, Canada. A total of 826 histologically verified cancer cases were individually matched by age, sex, and area of residence to 792 randomly selected population controls. Subjects were interviewed concerning their histories of exposure to a number of dietary factors, including table-top artificial sweeteners, low calorie foods and drinks, beverages containing caffeine or ethanol, and certain other food items. Also, subjects provided information on their past medical, occupational, and residential histories, in addition to their exposures to tobacco and other life-style factors. For the analysis, conditional logistic regression methods were used. Under adjustment for cumulative lifetime amount of cigarette smoking, the dietary factors, with little exception, were not associated with significant alteration of risk for bladder cancer. In particular, ever regular use of artificial sweeteners did not appear to be associated with increased risk, either among men (odds ratio = 0.95, p = 0.70) or among women (odds ratio = 1.15, p = 0.53). However, daily intake of cholesterol, calculated from reported frequencies of consumption of nine relevant food items, suggested a mild increase in risk; the odds ratio estimate of trend was 1.07/100 mg average daily intake (i.e., 1.07(5.5) = 1.45 for 550 mg cholesterol per day, as might be consumed in one egg; p = 0.009). A history of diabetes mellitus of onset after age 20 years also seemed to be associated with increased risk of bladder cancer (odds ratio = 1.65, p = 0.019), but this increase did not appear to be the result of use of insulin or other medications, or use of artificial sweeteners or low calorie foods. Thus, this study tends to confirm reports of a lack of association between use of artificial sweeteners and subsequent risk of bladder cancer.

Adult↗