Contraceptive methods and induced abortions and their association with the risk of colon cancer in Shanghai, China.

267400 female textile workers in Shanghai, who were administered a questionnaire at enrollment into a randomised trial of breast self-examination between October 1989 and October 1991, were followed up until the middle of 2000. Based on the 655 women who developed colon cancer, rate ratios (RRs) were estimated and trends in risk assessed using Cox Proportional Hazards Models. Risk was increased in women who used oral contraceptives for over 3 years (RR=1.56, 95% Confidence Interval (CI) 1.01-2.40). A possible increase in risk was also observed in women who received progestational injections during pregnancy (RR=1.24, 95% CI 0.95-1.62), but not in relation to the use of injectable contraceptives. A possible reduction in risk was associated with tubal ligation (RR=0.86, 95% CI 0.71-1.03) and ever having had an induced abortion (RR=0.84, 95% CI 0.71-1.00). No trends in risk were observed in relation to the duration of hormonal contraceptive use or the number of induced abortions. Additional studies of the possible roles contraceptives may play in the aetiology of colon cancer in women at low risk of this disease are warranted.

Sexual factors and the risk of prostate cancer.

A population-based case-control study of prostate cancer was performed in King County, Washington, in White men and Black men aged 40-64 years, between 1993 and 1996. Incident prostate cancer cases (n = 753) were identified from the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) cancer registry. Controls (n = 703) were identified through random digit dialing and were frequency matched to cases on age. Sexual behavior, medical history, and other potential prostate cancer risk factors were ascertained through an in-person interview. There was no relation between sexual orientation and prostate cancer, although the number of men who had sex with men was small. Risk estimates increased directly with the lifetime number of female sexual partners (trend p < 0.001) but not with male partners (trend p = 0.62). Risk also increased with decreasing age at first intercourse, but this effect disappeared after adjusting for the number of female partners. Prior infection with gonorrhea was positively associated with risk (odds ratio = 1.50; 95% confidence interval: 1.0, 2.2), but no effect was seen among men with other sexually transmitted diseases. No relation between lifetime frequency of sexual intercourse and risk of prostate cancer was apparent. These findings are consistent with previous studies that support an infectious etiology for prostate cancer.

The relationship between diet and breast cancer in men (United States).

OBJECTIVES: The purpose of this paper was to investigate the relationship between food and beverage consumption and the development of breast cancer in men. METHODS: Possible relationships of dietary factors to risk of breast cancer in men were assessed in a case-control study conducted between 1983 and 1986. Cases (N = 220) were ascertained from ten population-based cancer registries. Controls (N = 291) were selected by random-digit dialing (< age 65) and from Health Care Financing Administration Medicare beneficiary lists (> or = age 65). RESULTS: No trends in risk were observed with increasing intakes of specific foods, except for an increase in risk with citrus fruits. No increase in risk with increasing amounts of specific fats, vitamins, or minerals or with amounts of protein, fiber, carbohydrate, starches, nitrites, or alcohol consumed was observed, except for an increase in risk with dietary vitamin C consumption. A decreasing trend in risk with dietary niacin and with coffee and an increasing trend in risk with tea consumption were observed. No associations were found with use of any dietary supplements, including vitamin C. CONCLUSIONS: The observed associations are not consistent with findings from studies of breast cancer in women and probably do not represent causal relationships. Dietary factors are unlikely to be strong determinants of breast cancer in men.

Characteristics of women who use perineal powders.

OBJECTIVE: To examine demographic and behavioral factors related to perineal application of powders. METHODS: Controls from three case-control studies (N = 1206) were asked identical questions about the use of genital powders by direct perineal application. The relationship of perineal powder application with demographic factors, reproductive factors, body mass index (BMI), douching, and alcohol and tobacco use was assessed. Data were analyzed by multiple logistic regression. RESULTS: Women who douched (prevalence odds ratio [prevalence OR] 2.0, 95% confidence interval [CI] 1.0, 3.9), drank alcohol (prevalence OR 1.8, 95% CI 1.2, 2.8), smoked cigarettes (prevalence OR 1.3, 95% CI 1.0, 1.8), or were in the highest BMI quartile were more likely to engage in perineal use of powder (prevalence OR 1.6, 95% CI 1.1, 2.6). There appeared to be a close response relationship between the number of perineal applications of powder and BMI (P < .002). CONCLUSION: Body mass index might confound the relationship between perineal powder application and the development of ovarian cancer. Other factors, such as alcohol and tobacco use and douching, are related to perineal use of powder and may represent similar behavioral characteristics.

Intrauterine devices and endometrial cancer. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

The relationship between intrauterine device (IUD) use and the development of endometrial cancer was assessed in data from seven countries that were collected between 1979 and 1988 for a multinational hospital-based case-control study. Two hundred twenty-six cases of endometrial cancer were compared with 1,529 controls matched for age, hospital, and year of interview. No significant association between use of an IUD and risk of endometrial cancer was observed (OR = 0.74, 95% CI = 0.4-1.33). There were no trends in risk with respect to duration of use, time since first use, or ages at first or last use. No cases had used a copper IUD (OR = 0, 95% CI = 0-1.71). Although women over age 55 who had used an IUD were at significantly increased risk, this unexpected finding is based on small numbers of users and requires independent confirmation. These results, along with those from other studies, provide reassurance that risk of endometrial cancer is unlikely to be increased by use of an IUD.

Reduced risk of ovarian cancer in women with a tubal ligation or hysterectomy. The World Health Organization Collaborative Study of Neoplasia and Steroid Contraceptives.

Possible relationships between tubal ligation and hysterectomy and epithelial ovarian cancer were assessed in data that were collected for a multinational hospital-based case-control study conducted between 1979 and 1988. Histologically confirmed incident cases (n = 393) were compared with controls (n = 2563) matched on age, hospital, and year of interview. A nonsignificant reduction in risk was observed for tubal ligation [odds ratio (OR), 0.72; 95% confidence interval (CI), 0.48-1.08] and hysterectomy (OR, 0.58; 95% CI, 0.26-1.27). There was no trend in risk with time since tubal ligation. The possible protective effect of tubal ligation was greatest in women of parity less than four. The apparent protective effect of tubal ligation was seen only for clear cell (OR, 0.32; 95% CI, 0.006-2.50) and endometrioid (OR, 0.20; 95% CI, 0.046-1.46) tumors, suggesting a hormonal mechanism for the observed associations.

Liver cancer in Asian migrants to the United States and their descendants.

The incidence of primary liver cancer in Chinese, Japanese, and Filipino migrants to the United States and their descendants is compared with that of United States-born Whites. Incident liver cancer cases were ascertained between 1973 and 1986 from population-based cancer registries serving the San Francisco/Oakland (CA) metropolitan area, 13 counties of western Washington, and Hawaii. The population of these three areas, with regard to age, race, and country of birth, was estimated from a special tabulation of the 1980 US census. Rates of primary liver cancer were higher for men born in Asia than Asian men born in the US, who, in turn, had higher rates than did US Whites (respective annual rates per 100,000: Chinese, 26.5 and 9.8; Japanese, 16.5 and 6.6; Filipinos, 11.4 and 6.5; US Whites, 3.4). Among Asian American women, the trends were not as consistent (respective annual rates per 100,000: Chinese, 2.2 and 3.7; Japanese, 1.9 and 1.4; Filipino, 2.6 and 0; US Whites, 1.1). In general, liver cancer incidence among Asian Americans was lower than among residents of Asia. These findings are compatible with substantial variation among Asians in the prevalence of one or more etiologic factors for liver cancer, such as hepatitis-B infection and aflatoxin consumption, in relation to residence and place of birth.

Prolonged lactation and endometrial cancer. WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

BACKGROUND: The risk of endometrial cancer is related to oestrogen levels, showing an increased risk with increasing endogenous or exogenous oestrogen stimulation and a reduced risk when oestrogen is opposed by progesterone. During breastfeeding, the reduction of endogenous oestrogen exposure is larger than that of progesterone, suggesting that breastfeeding may possibly reduce the risk of endometrial cancer. METHODS: The relationship between lactation and endometrial cancer was assessed in data from six countries, including four developing countries, that were collected for a multinational hospital-based case-control study conducted between 1979 and 1988. In all, 136 cases were compared with 933 controls matched on age, hospital, and year of interview. Standardized questionnaires, administered in the local language, ascertained information on the length of time breastfed, age started and stopped breastfeeding, reproductive and contraceptive practices, and other risk factors for endometrial cancer. Conditional logistic regression was used to control for the confounding effects of gravidity and age at menarche. RESULTS: Significant decreasing trends in risk were observed with increasing duration of lactation, and with months of breastfeeding per pregnancy. Risk was lowest in women who had most recently lactated, and the apparent protective effect declined with time since cessation of breastfeeding, so that there was no evidence for a protective effect after age 55 even in women who had breastfed for over 5 years. CONCLUSIONS: The long-term lactation that takes place in developing countries probably reduces the risk of endometrial cancer, but this effect may not persist into the ages at which this disease is most common.

Lactation and the risk of epithelial ovarian cancer. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

The relationship between lactation and the development of epithelial ovarian cancer was assessed in data from seven countries that were collected for a multinational hospital-based case-control study conducted between 1979 and 1988. Three hundred and ninety-three cases of ovarian cancer were compared to 2565 controls matched on age, hospital, and year of interview. A non-significant reduction in risk with short-term lactation was observed but no further reduction in risk was seen with long-term lactation. The reduction in risk associated with months of lactation was not as great as the reduction with months of pregnancy, which may be a result of lactation being a less effective form of ovulation suppression than pregnancy. The short-term lactation that takes place in developed countries, may provide as great a reduction in risk as the long-term lactation practised in the developing countries included in this study.

Histologic types and hormone receptors in breast cancer in men: a population-based study in 282 United States men.

Histologic slides from 282 incident cases of breast cancer in men, that were identified in 10 population-based cancer registries in the United States, were reviewed by a single pathologist. Breast cancer more often presented in the noninvasive stage in men (10.8 percent of all cases) than would be expected among women. All noninvasive carcinomas were of the ductal type. Of invasive carcinomas, compared with women, men had smaller proportions of lobular and mucinous types and larger proportions of ductal and papillary types and Paget's disease. No case of tubular or medullary carcinoma was seen. The breast in men is composed only of ducts and normally contains no lobules, and the histologic types of breast carcinomas that predominate in men are likely of ductal origin. Estrogen and progesterone receptors were present in 86.7 percent and 76.3 percent of invasive carcinomas, respectively, which are higher proportions than would be expected among women. Also, unlike findings in women, receptor content was not associated with patient age at diagnosis.

High-dose and low-dose combined oral contraceptives: protection against epithelial ovarian cancer and the length of the protective effect. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

The relations between use of high-dose and low-dose combined oral contraceptives and epithelial ovarian cancer were compared in an international hospital-based case-control study. 393 cases from seven countries were compared with 2561 matched controls. The odds ratio (OR) was somewhat lower for women who used high-dose oestrogen oral contraceptives (OR = 0.68) than for women who used low-dose preparations (OR = 0.81) although the difference could have occurred by chance. After controlling for time since last use, risk was slightly lower for long-term users of high-dose preparations than for long-term users of low-dose pills. Both high-dose and low-dose oral contraceptives protect against ovarian cancer, but the degree of protection may be slightly weaker for the newer, low-dose products.

Hormonal content of combined oral contraceptives in relation to the reduced risk of endometrial carcinoma. The WHO Collaborative Study of Neoplasia and Steroid Contraceptives.

The relationship between the strength of the estrogenic and progestational components of combined oral contraceptives and risk of endometrial carcinoma was examined in a multinational hospital-based case-control study comparing 220 cases from 7 countries with 1,537 age- and hospital-matched controls. Oral contraceptives were classified according to their relative content of estrogen and progestin. The risk was not altered in women who used preparations containing high-dose estrogen/low-dose progestin compounds [odds ratio (OR) = 1.10, 95% CI = 0.13-9.96]. In contrast, the risk among users of low-dose estrogen/high-dose progestin oral contraceptives was greatly decreased (OR = 0, 95% CI = 0-1.08). Risks observed for users of high-dose estrogen/high-dose progestin (OR = 0.15, 95% CI = 0.045-0.50) and low-dose estrogen/low-dose progesterone (OR = 0.59, 95% CI = 0.26-1.30) preparations were intermediate between those for users of the 2 other types of preparation. A significantly lower risk was observed for high-dose progestin users than for low-dose users [ratio of odds ratios (ROR) = 0.21, 95% CI = 0.05-0.84]. Although the numbers are small, findings from this study suggest that combined oral contraceptives with varying strengths of estrogen and progestin have different effects on the risk of endometrial carcinoma.

Occupational exposure to electromagnetic fields and breast cancer in men.

Data from a population-based case-control study of breast cancer in men were used to examine the hypothesis that occupational exposure to electromagnetic fields increases the risk of breast cancer. Incident cases (n = 227) diagnosed between 1983 and 1987 were obtained from 10 population-based cancer registries of the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. Controls (n = 300) were selected by random digit dialing and from Medicare eligibility lists. Exposure status, defined as ever having been employed in a job which has been classified as involving potential exposure to electromagnetic fields, was assigned without knowledge of case/control status. An elevated risk was found for any job with exposure (odds ratio (OR) = 1.8, 95 percent confidence interval (CI) 1.0-3.7), and risk was highest among electricians, telephone linemen, and electric power workers (OR = 6.0, 95 percent CI 1.7-21) and radio and communications workers (OR = 2.9, 95 percent CI 0.8-10). Risk did not vary with duration of exposed employment. The risk was highest among subjects who were first employed in jobs with exposure before the age of 30 years and who were initially exposed at least 30 years prior to diagnosis. These results lend support to the theory that electromagnetic fields may be related to breast cancer in men. The hypothesis warrants evaluation in women.

Antigenic stimulation and the occurrence of chronic lymphocytic leukemia.

Data from a population-based case-control study of chronic lymphocytic leukemia were analyzed to assess the possible etiologic role of chronic antigenic stimulation. The study, conducted in four geographic areas of the United States (the metropolitan areas surrounding Seattle, Washington, Salt Lake City, Utah, Detroit, Michigan, and Atlanta, Georgia) sought to identify all incident cases (n = 430) among residents diagnosed between July 1, 1977 and December 31, 1981. The responses of these cases to questions about possible sources of antigenic stimulation were compared with the responses of controls selected from the populations of these areas. Little difference between cases and controls was present for a history of most forms of viral and bacterial infection and for a history of allergies or allergy treatment. However, a relation was observed with antecedent syphilis infection (odds ratio (OR) = 5.0, 95% confidence interval (Cl) 2.0-12.9). Associations of smaller magnitude were observed with a history of tuberculosis (OR = 1.9, 95% Cl 1.0-3.7) and of urinary tract infection (OR = 1.4, 95% Cl 1.1-1.9). Overall, however, the authors found little evidence of a relation between chronic antigenic stimulation and the occurrence of chronic lymphocytic leukemia. Nonetheless, because the measure of prior antigenic stimulation was restricted to that obtained through interviews and undoubtedly was an insensitive one, these negative results should not be interpreted as ruling out antigenic stimulation as a possible cause of some cases of chronic lymphocytic leukemia.

Breast cancer in men: aspects of familial aggregation.

Familial aggregation of breast cancer in males was investigated in a population-based case-control study. Cases were ascertained from 10 Surveillance, Epidemiology, and End Results Program registries in the United States between 1983 and 1986. Controls were identified by random-digit dialing and from lists of Medicare recipients. The relative odds of developing breast cancer were similar in men with affected paternal and maternal relatives and in men with affected mothers and sisters. The risk increased with the number of affected relatives. The relative odds of developing breast cancer were greater in men with first-degree relatives who developed their mammary neoplasm before the age of 45 than in men with older first-degree affected relatives; the enhancement of risk in men with an affected sister was greater in those under age 60 than in older men. These results are similar to those observed by others in studies of breast cancer in women.

Incidence of malignant fallopian tube tumors.

Incidence rates were examined for epithelial malignant fallopian tube neoplasms diagnosed between 1973 and 1984 and reported to nine population-based cancer registries in the United States. The average annual incidence was 3.6 per million women per year and there was no evidence of a change in the rate during the study period. Age-specific incidence followed a pattern similar to that observed for ovarian and endometrial neoplasms, rising rapidly during the reproductive years and flattening out thereafter. The incidence rate varied only slightly by race, with whites having a higher rate than blacks. Considerable variation in incidence was observed among the registries. While this could have been due to true regional differences in incidence, we cannot rule out the possibility that misclassification of fallopian tube tumors as ovarian tumors was responsible. Further investigations into the etiology of fallopian tube neoplasms should focus on the role of reproductive factors that have previously been reported as risk factors for ovarian and endometrial neoplasms.