Oral contraceptive use and breast cancer risk among African-American women

Recent epidemiologic studies, most of them in predominantly White populations, have suggested that long duration of oral contraceptive (OC) use may increase the risk of breast cancer at young ages. We assessed the relationship of OC use to the risk of breast cancer in African-American women aged 25 to 59 years, using interview data from a multipurpose hospital-based case-control study. Five hundred and twenty-four cases hospitalized for invasive breast cancer were compared with 1,021 controls with nonmalignant conditions unrelated to OC use. Relative risks (RR) and 95 percent confidence intervals (CI) were estimated relative to a reference category of use for less than 12 months; potential confounders were controlled by multiple logistic regression analysis. Among women under age 45, three or more years of OC use was associated with an increased risk of breast cancer: the RR estimate was 2.8 (CI=1.5–5.0) for three to four years of use, and declined to 1.5 (CI=0.8.3.0) for 10 or more years of use. Recency and timing of use did not explain the observed association. Among women aged 45 to 59, OC use was associated with little or no increase in risk: the RR estimate for three or more years of use was 1.3 (CI=0.7–2.4). The findings add to the evidence from studies of White women and a recent study of Black women which have suggested an increased risk of breast cancer at young ages for moderate or long duration use of OCs.This research was supported by the US National Cancer Institute (grants R01 CA55766 and R01 CA45762). Additional support was provided by the US Food and Drug Administration (FD-U-000082); the views expressed do not necessarily represent the views of the Food and Drug Administration. The Slone Epidemiology Unit also receives support from Hoffmann-La Roche, Inc., and Marion Merrell Dow Inc.     

Noncontraceptive hormone use and risk of breast cancer

All British Columbia (Canada) women under 75 years of age who were diagnosed with breast cancer during 1988–89 were asked to complete a postal questionnaire which included detailed information on menopausal estrogen use. Controls were drawn from the Provincial Voters List, matched by five-year age category to the cases. The present analysis consists of 699 cases and 685 controls who were postmenopausal due to natural causes or to a hysterectomy. There was no overall increase in risk of breast cancer associated with ever-use of unopposed estrogen (odds ratio [OR] = 1.0,95 percent confidence interval [CI] = 0.8–1.3). For estrogen use of 10 years or longer, the relative risk [RR] was 1.6 (CI = 1.1–2.5). The risk estimate for current users was somewhat elevated (OR = 1.4, CI = 1.0–2.0). Compared with women who never used hormone preparations, women who had used estrogen plus progestogen had an RR of 1.2 (CI = 0.6–2.2). Our results suggest that ever-use of estrogen, with or without progestogen, does not appreciably increase the risk of breast cancer. However, long-term and recent use of unopposed estrogen may be associated with a moderately increased risk.Drs Yang and Band, and Mr Gallagher are with the British Columbia Cancer Agency, Vancouver, Britsh Columbia, Canada. Authors are also affiliated with the School of Public Health and Community Medicine, University of Washington, Seattle, WA, USA (Drs Yang, Daling, White, and Weiss), and the Fred Hutchinson Cancer Research Center, Seattle, WA, USA (Drs Daling, White, and Weiss). Address correspondence to Mr Gallagher, Division of Epidemiology, Biometry and Occupational Oncology, British Columbia Cancer Agency, 600 West 10th Avenue, Vancouver, BC, Canada, V5Z 4E6. This project is funded partially by Health and Welfare Canada, Grant #6610-1834-55 and by Workers Compensation Board of BC.     

Oral contraceptives and breast cancer in northern Italy. Final report from a case-control study.

To assess the relation between oral contraceptive (OC) use and breast cancer, we analysed data from a case-control study conducted in Northern Italy between 1983 and 1991 on 2,309 cases below age 60 and 1,928 controls admitted to hospital for acute diseases unrelated to OC use and to any of the known or potential risk factors for breast cancer. OC use was reported by 16% of cases and 14% of controls. The multivariate relative risk (RR) for ever vs never use of combination OC was 1.2 (95% confidence interval (CI) 1.0-1.4). However, there was no trend in risk with duration. The RR was elevated for very short use, but declined to 0.8 (95% CI = 0.5-1.0) for five or more years'' use. No noteworthy relationship was found for other major measures of OC use, although RR estimates were above unity for women who had stopped use less than 5 years before (RR = 1.5, 95% CI = 1.1-2.0), started use less than 10 years before (RR = 1.3, 95% CI = 1.0-1.9), started when 25 or more years old (RR = 1.4, 95% CI = 1.1-1.7), or after first birth (RR = 1.2, 95% CI = 1.0-1.5). No interaction was observed between OC use and family history of breast cancer, parity and age at first birth. A separate analysis of 373 cases and 456 control below age 40 showed no association with ever use (RR = 0.9, 95% CI = 0.6-1.2).     

Oral contraceptives and risk of benign proliferative epithelial disorders of the breast.

In a case-control study conducted in Adelaide, South Australia, we investigated the hypothesis that use of oral contraceptives is associated with increased risk of benign proliferative epithelial disorders (BPED) of the breast, conditions strongly associated with increased risk of breast cancer and thought to have pre-malignant potential. The study was restricted to women with no prior history of breast biopsy, and involved 383 cases of biopsy-confirmed BPED, 192 controls whose biopsy did not show epithelial proliferation, and 383 unbiopsied community controls individually matched to cases by age and socio-economic grading of area of residence. When cases were compared with community controls, the adjusted odds ratio (OR) for the association between ever-use of oral contraceptives and risk of BPED was 1.1 (95% CI 0.7 to 1.7), while when cases were compared with biopsy controls, the adjusted OR was 0.9 (95% CI 0.5 to 1.5). There was little variation in risk of BPED with total duration of use of oral contraceptives, and with duration of use before first pregnancy, while current users had a statistically significant 60% reduction in risk, irrespective of the control group used for comparative purposes. Also, there was little variation in risk with years since first and last use of oral contraceptives, and there was no trend in the association between ever-use of oral contraceptives and risk of BPED by degree of cytological atypia.     

Oral contraceptive use and risk of cutaneous malignant melanoma in a case-control study of French women

We report the results of a case-control study designed to analyze the relationship between oral contraceptive use (OC) and the risk of cutaneous malignant melonama (MM) in 240 White women under the age of 45. Five French centers participated in the study between February 1982 and January 1987 for periods of eight to 54 months, depending on the center. Cases were 91 consecutive newly diagnosed patients with histologically verified MM. Each case was matched with one or two controls on year of birth, date of interview, and treatment center. Controls were 149 patients with either malignant or nonmalignant disease who came to the center for diagnosis and treatment. Odds ratios (OR) were estimated by multivariate analyses taking into account age at menarche, sunlight exposure, and skin characteristics. No significant relation was found between the risk of MM and the total duration of OC use, age at start of use, and elapsed time since the first OC use. However, when the analysis was restricted to women aged 30–40 years, i.e., those who were able to use OC for 10 years or more, or who had started OC use 15 years or more before the diagnosis, the risk of MM increased significantly with the duration of OC use (P=0.03). A total of more than 4,000 hours of sunlight exposure, and menarche before the age of 14 also were found to increase significantly the risk of MM (OR=5.4, 95 percent confidence interval [CI]=1.6–18.3; and OR=3.6, CI=1.0–12.5, respectively).This study was made possible by a grant from the Institut Goustave Roussy (Contract no. 85-D-9).     

A case-control study of melanomas of the soles and palms (Australia and Scotland)

Objectives: Because the factors that influence risk of acral melanomas on the soles and palms in White populations are unknown, we investigated these in a multi-center case-control study.Methods: Cases of melanoma of the feet and hands diagnosed from 1987–93 in persons aged over 18 years were ascertained in eastern Australia and western Scotland. There were 275 cases of melanoma on the soles and palms matched to 496 controls (selected from the electoral roll) in Australia, and 36 cases matched to 72 controls (nominated by general practitioners) in Scotland.Results: Acral melanoma was strongly associated with high total body nevus counts (adjusted relative risk [RR]=6.3, 95% confidence interval [CI]=2.5–15.6), and with nevi on the soles (RR=7.5, CI=3.0–18.6). There were also significant positive associations with a penetrative injury of the feet or hands (RR=5.0, CI=3.0–8.6) and with heavy exposure to agricultural chemicals (RR=3.6, CI=1.5–8.3). Sun-sensitive complexions, cumulative sun exposure and a past history of nonmelanoma skin cancer were also associated with increased risk of acral melanoma. Current cigarette smoking was inversely related to acral melanoma (RR=0.6, CI=0.4–0.9).Conclusions: Melanomas of the soles and palms resemble other cutaneous melanomas in their association with sun exposure, but are distinguished from them by their strong positive associations with nevi on the soles, previous penetrative injury, and exposure to agricultural chemicals, and by their inverse association with smoking.     

Estrogen replacement therapy and risk of fatal breast cancer in a prospective cohort of postmenopausal women in the United States

This study examines the relationship between fatal breast cancer and use of estrogen replacement therapy (ERT) among women in a large prospective study in the United States. After nine years of follow-up, 1,469 breast cancer deaths were observedin a cohort of 422,373 postmenopausal women who were cancer free at study entry and who supplied information on estrogen use. Results from Cox proportional hazards modeling, adjusted for 11 other potential risk factors, showed that ever-use of ERT was associated with a significantly decreased risk of fatal breast cancer (rate ratio [RR]=0.84,95 percent confidence interval [CI]=0.75–0.94). There was a moderate trend (P=0.07) of decreasing risk with younger age at first use of ERT. This decreased risk was most pronounced in women who experienced natural menopause before the age of 40 years (RR=0.59, CI=0.40–0.87). There was no discernible trend of increasing risk with duration of use in estrogen users at baseline or former users, nor was there any trend in years since last use in former users. The relationship between ERT and breast cancer mortality differed by age at menarche and by a self-reported history of breast cysts. No increased risk of fatal breast cancer with ERT was observed with estrogen use status (baseline/former), age at first use, duration of use, or years since last use. These findings suggest that ever-use of ERT is associated with a 16 percent decreased risk of fatal breast cancer.     

Exogenous hormone use and the risk of postmenopausal breast cancer: results from the Netherlands Cohort Study

The association between the use of exogenous hormones as either oral contraceptives (OC) or hormone replacement therapy (HRT) in relation to postmenopausal breast cancer incidence was examined in the Netherlands Cohort Study (NLCS) among 62,573 women aged 55 to 69 years. Information on these types of exogenous hormone use and other risk factors was collected by mailed questionnaire. During 3.3 years of follow-up, 471 incident breast cancer cases were identified. After adjustment for traditional breast cancer risk factors, the relative risk (RR) of breast cancer was 1.09 (95 percent confidence interval [CI]=0.79–1.48) for women who ever used OCs cf women who never used OCs. The relative rates (with CIs) for women who used OCs for a period < 5 years, 5–9 years, 10–14 years, and 15+ years were 0.97 (0.61–1.55), 1.20 (0.69–2.07), 1.03 (0.60–1.77), and 1.96 (0.99–3.89), respectively. The test for trend was not significant (P=0.13). There was no evidence of any association between the number of years between the first and the last use of OCs and breast cancer incidence. In the subgroup of women with first-degree relatives with breast cancer, the RR for breast cancer associated with ever use of OCs was 1.51 (CI=0.67–3.41), whereas in the remaining women, the RR was 0.97 (CI=0.73–1.27). Ever-use of HRT compared with never-use was not associated with an increase in breast cancer risk in the multivariate analysis (RR=0.99, CI=0.68–1.43). Also, the number of years of HRT use was not associated with an increased breast cancer risk (trend P=0.83), nor was the number of years between the first and the last use of HRT and breast cancer incidence. One subgroup of women in which the use of HRT seemed associated (but not significantly) with an increase in breast cancer risk was women with an induced menopause (RR=1.72, CI=0.95–3.12). The RR of breast cancer for women who had ever used both OCs and HRT, compared with women who never used these exogenous hormones was 1.00 (CI=0.51–1.94). From this study, it cannot be concluded that the use of exogenous hormones is a strong risk factor for the development of postmenopausal breast cancer.Since the acceptance of this paper, two other papers have been published on HRT and breast cancer. For HRT (estrogen alone), one supports our finding of no association (Stanford et al, JAMA 1995; 274: 137–42) and one did find a positive association for current use (Colditz et al, New Engl J Med 1995; 332: 1589–93), most pronounced in older women with longer durations of use. With regard to use of combined estrogen-progestin HRT, the results in both papers were comparable to those for estrogen alone. More research on (combinations of) types of hormones is needed.This work was supported by the Dutch Cancer Society.     

Marijuana use and cancer incidence (California, United States)

The purpose of this retrospective cohort study was to examine therelationship of marijuana use to cancer incidence. The study populationconsisted of 64,855 examinees in the Kaiser Permanente multiphasic healthcheckup in San Francisco and Oakland (California, United States), between1979-85, aged 15 to 49 years, who completed self-ad-ministered questionnairesabout smoking habits, including marijuana use. Follow-up for cancer incidencewas conducted through 1993 (mean length 8.6 years). Compared withnonusers/experimenters (lifetime use of less than seven times), ever- andcurrent use of marijuana were not associated with increased risk of cancer ofall sites (relative risk [RR] = 0.9, 95 percent confidence interval [CI] =0.7-1.2 for ever-use in men; RR = 1.0, CI = 0.8-1.1 in women) in analysesadjusted for sociodemographic factors, cigarette smoking, and alcohol use.Marijuana use also was not associated with tobacco-related cancers or withcancer of the following sites: co lorectal, lung, melanoma, prostate, breast,cervix. Among nonsmokers of tobacco cigarettes, ever having used marijuanawas associated with increased risk of prostate cancer (RR = 3.1, CI =1.0-9.5) and nearly significantly increased risk of cervical cancer (RR =1.4, CI = 1.0-2.1). We conclude that, in this relatively young study cohort,marijuana use and cancer were not associated in overall analyses, but thatassociations in nonsmokers of tobacco cigarettes suggested that marijuana usemight affect certain site-specific cancer risks.     

Oral contraceptive use and risk of melanoma in premenopausal women.

Melanoma has been increasing in white populations. Incidence rates rise steeply in women until about age 50, suggesting oestrogen as a possible risk factor. Oestrogens can increase melanocyte count and melanin content and cause hyperpigmentation of the skin. We examined prospectively the association between oral contraceptive (OC) use and diagnoses of superficial spreading and nodular melanoma among 183,693 premenopausal white women in the Nurses' Health Study (NHS) and the Nurses' Health Study II (NHS II) cohorts. One hundred and forty six cases were confirmed in NHS during follow-up from 1976 to 1994, and 106 cases were confirmed in NHS II from 1989 to 1995. Skin reaction to sun exposure, sunburn history, mole counts, hair colour, family history of melanoma, parity, height and body mass index were also assessed and included in logistic regression models. A significant twofold increase in risk of melanoma (relative risk (RR) = 2.0, 95% confidence interval (CI) 1.2-3.4) was observed among current OC users compared to never users. Risk was further increased among current users with 10 or more years of use (RR = 3.4, 95% CI 1.7-7.0). Risk did not appear elevated among past OC users, even among those with longer durations of use, and risk did not decline linearly with time since last use. In conclusion, risk of premenopausal melanoma may be increased among women who are current OC users, particularly among those with longer durations of use. Further research is needed to determine whether low-dose oestrogen pills in particular are associated with an increase in risk and to describe possible interactions between OC use and sun exposure or other risk factors for melanoma.     

Oral contraceptives and malignant melanoma

Several studies have suggested that prolonged use of oral contraceptives may increase a woman's risk of developing malignant melanoma. In the Royal College of General Practitioners' Oral Contraception Study, 31 cases of malignant melanoma (code 172--International Classification of Diseases, 8th Revision) have been reported among ever-users and 27 cases among never-users. The risk ratio (RR) (indirectly standardised for age, parity, social class and smoking) was 0.92 (95% confidence interval (CI) 0.55-1.54). There was no significant trend with duration of oral contraceptive use, although those women who had used the pill for at least 10 years had an elevated RR of 1.77 (95% CI 0.80-3.90). The Oxford/Family Planning Association Study has recorded 15 cases among ever-users and 17 cases among never-users; the standardised risk ratio was 0.85 (95% CI 0.42-1.70). None of the rates observed in any duration of use category was materially different from those observed in never-users. The results available so far from the two studies suggest that oral contraceptive use is probably not associated with an increased risk of malignant melanoma.     

Recent oral contraceptive use and risk of breast cancer (United States)

We examined the association between recent oral contraceptive (OC) use and the risk of breast cancer in data from a large population-based case-control study in the United States. Cases (n=6,751) were women less than 75 years old who had breast cancer identified from statewide tumor registries in Wisconsin, Massachusetts, Maine, and New Hampshire. Controls (n=9,311) were selected randomly from lists of licensed drivers (if aged under 65 years) and from lists of Medicare beneficiaries (if aged 65 through 74 years). Information on OC use, reproductive experiences, and family and medical history was obtained by telephone interview. After adjustment for parity, age at first delivery, and other risk factors, women who had ever used OCs were at similar risk of breast cancer as never-users (relative risk [RR]=1.1, 95 percent confidence interval [CI]=10–1.2). Total duration of usealso was not related to risk. There was a suggestion that more recent use was associated with an increased risk of breast cancer; use less than two years ago was associated with an RR of 1.3 (CI=0.9–1.9). However, only among women aged 35 to 45 years at diagnosis was the increase in risk among recent users statistically significantly elevated (RR=2.0, CI=1.1–3.9). Use prior to the first pregnancy or among nulliparous women was not associated with increased risk. Among recent users of OCs, the risk associated with use was greatest among non-obese women, e.g., among women with body mass index (kg/m²) less than 20.4, RR=1.7, CI=1.1–2.8. While these results suggest that, in general, breast cancer risk is not increased substantially among women who have used OCs, they also are consistent with a slight increased risk among subgroups of recent users.Authors are with the University of Wisconsin Comprehensive Cancer Center, Madison, WI, USA (Dr Newcomb, Ms Trentham Dietz); NIEHS Epidemiology Branch, Research Triangle Park, NC (Dr Longnecker); Fred Hutchinson Cancer Research Center, Seattle, WA (Dr Surer); Department of Obstetrics and Gynecology, Pritzker School of Medicine, The University of Chicago, Chicago, IL (Dr Mittendorf); Department of Community and Family Medicine, Dartmouth Medical School, Hanover, NH (Dr Baron); Boston University, School of Public Health, Boston, MA (Dr Clapp); Department of Epidemiology and Department of Nutrition, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School and Department of Medicine, Brigham and Women's Hospital, Boston, MA (Dr Willett). Address correspondence to: Dr Polly A. Newcomb, University of Wisconsin-Madison Comprehensive Cancer Center, 1300 University Ave., #4780, Madison, WI 53706, USA. Supported by Public Health Service (National Cancer Institute) grants R01 CA 47147 and R01 CA 47305.     

Prospective study of exogenous hormone use and breast cancer in Seventh-day Adventists

Exogenous hormone use as either oral contraceptives (OC) or hormone replacement therapy (HRT) was evaluated in reference to subsequent breast cancer risk in a cohort study of 20,341 Seventh-day Adventist women, residing in California, who completed a detailed lifestyle questionnaire in 1976 and who were followed for 6 years. During the follow-up period, 215 histologically confirmed primary breast cancers were detected in the cohort. The mean age at diagnosis was 66 years, indicating a primarily postmenopausal case series. In this cohort, after taking into account potentially confounding variables, current use of HRT (in 1976) was associated with a 69% increase in breast cancer risk, which was statistically significant (RR = 1.69; CI = 1.12-2.55). However, there was no strong increase in risk with increasing duration of use of HRT. Subgroups of women who did experience HRT associated increases in breast cancer risk included those women who had ever used HRT (RR = 1.39; CI = 1.00-1.94) and those with no history of maternal breast cancer (RR = 1.45), those women with prior benign breast disease (RR = 2.80), and those women who experienced menopause at 44 years of age or later (RR = 1.56). There was no substantial increase in breast cancer risk associated with use of OC in this population, although among women with exposure to both OC and HRT there was a suggested increase in risk (RR = 1.42; CI = 0.71-2.85).     

Oral contraceptives and the risk of endometrial cancer

The relationship between the use of combbination oral contraceptives (OCs) and the risk of endometrial cancer was assessed in a case-control study conducted in the Swiss Canton of Vaud between 1 January 1988 and 31 July 1990. Subjects included 122 women aged 75 or less with histologically confirmed endometrial cancer, and 309 control women in hospital for acute conditions unrelated to OC use. Overall, 14 percent of cases and 27 percent of controls had ever used OCs, corresponding to a multivariate relative risk (RR) of 0.5 (95 percent confidence interval [CI]: 0.3. 0.8). The risk of endometrial cancer was found to be related inversely to duration of OC use: RR=1.0 for less than two years of OC use; 0.5 for two to five years; and 0.3 (95 percent CI: 0.1, 0.7) for more than five years. The protection appeared greater within 20 years since last use, and the RR rose to 0.8 after 20 or more years since last use; numbers are too small, however, for reliable inference from these subanalyses. No significant interaction or modifying effect was observed with other major factors related to endometrial cancer, including parity, body mass index, estrogen replacement therapy, and cigarette smoking. While this study provides further evidence for the protective effect of OCs against risk of endometrial cancer, the relationship requires continued evaluation to assess the long-term implications and public health impact of OC use.This work was supported in part by the Swiss National Science Foundation Grant No. 3.866-0.88.     

Female hormone utilisation and risk of hepatocellular carcinoma.

The relationship between female hormone use and primary liver cancer was analysed using data from a case-control study conducted between 1984 and 1992 in Milan on 82 female incident cases with histologically or serologically confirmed hepatocellular carcinoma and 368 controls admitted to hospital for acute non-neoplastic, non-hormone-related diseases. An elevated relative risk (RR) or primary liver cancer was observed in oral contraceptive (OC) users (RR 2.6, for ever versus never users, 95% confidence interval, CI 1.0-7.0). The RR was directly related to duration of use (RR 1.5 for < or = 5 years and 3.9 for > 5 years) and persisted for longer than 10 years after stopping use (RR 4.3%, 95% CI 1.0-18.2). The RR were below unity, although not significantly, for women ever using oestrogen replacement therapy (RR 0.2, 95% CI 0.03-1.5) and female hormones for indications other than contraception and menopausal therapy (RR 0.4, 95% CI 0.1-1.5). The long-lasting, association between risk of hepatocellular carcinoma and OC use has potential implications on a public health scale, since primary liver cancer is a relatively rare disease among young women, but much more common at older ages. This study provides limited but reassuring evidence on the possible relationship between oestrogen replacement treatment and subsequent risk of hepatocellular carcinoma.     

Multiple myeloma and family history of cancer. A case-control study

A hospital-based case-control study was done to examine the hypothesis that persons with a family history of multiple myeloma (MM) or other cancers are at increased risk of multiple myeloma. Study members were 439 cases of multiple myeloma and 1317 matched controls seen at the Duke University Medical Center. Only 3 cases and 4 controls reported multiple myeloma in their families. The relative risk (RR) was 2.3, but the 95% confidence interval (CI) was 0.5-10.1, allowing no firm conclusion about the risk associated with familial MM. A family history of cancer of any type resulted in a relative risk of MM of 1.4 (CI: 1.1-1.8). This association was strongest (RR = 2.5, CI: 1.1-5.3) among young study members (age less than or equal to 49). A family history of hematologic malignancy (ICD 200-208) resulted in a RR of 2.4 (95% CI: 1.4-4.0). The data also suggested that a family history of lung cancer, breast cancer, and genitourinary cancer may be associated with increased risk of myeloma in older persons.     

Recency,duration, and progestin content of oral contraceptives in relation to the incidence of endometrial cancer (Washington,USA)

Women who have used combined oral contraceptives (COC) have a reduced risk of endometrial cancer relative to that of women who have never used oral contraceptives, but it is unclear whether the size of the reduction is influenced by the progestin content of the preparation. We analyzed data from two population-based case-control studies of endometrial cancer to investigate this question. Among women aged 40 to 59 years who were residents of King or Pierce Counties, Washington (United States), incident cases who were diagnosed during 1975–77 or 1985–87 were identified. Personal interviews were conducted with 316 such women and their responses compared with those of 501 controls who were selected by household surveys or random-digit dialing. A reduced risk of endometrial cancer associated with COC use was present only among users of five or more years' duration, and even then only in women who were not long-term users of unopposed postmenopausal estrogens. Among these women, the relative risk (RR) of endometrial cancer did not differ according to the progestin potency of the COC used: it was equally low for women who had used a COC with low progestin content (RR=0.2, 95 percent confidence interval [CI]=0.1–0.8) as for women who had used a COC with high progestin content (RR=0.3, CI=0.1–0.9). Our results argue that, if the reduced risk of endometrial cancer in long-term users of COCs is due to the progestins contained in these preparations, that amount of progestin in most COCs exceeds the threshold amount needed to produce this beneficial effect.This project was supported by Grant 5R35CA39779 and Contract NO1-CN-05230 from the US National Cancer Institute.     

Association of basal cell skin cancers with other cancers (United States)

Background: Persons with basal cell skin cancer (BCSC) have shown increased risk of developing cancer at several other sites. Methods: We identified 3164 persons with BCSC and 15,730 comparison subjects matched for age, sex, race, residence area and length of membership in a health maintenance organization. Results: In retrospective follow-up for up to 24 years (mean 11.3 years), BCSC patients experienced statistically significant increases in the incidence of all cancer (relative risk [RR] = 1.2, 95% confidence interval [CI] = 1.1–1.4) lung cancer (RR = 1.4, CI = 1.0–1.8) and melanoma (RR = 2.2, CI = 1.6–3.0). Women experienced significantly increased risk for all cancer, lung cancer, melanoma and thyroid cancer, increases of borderline significance in breast cancer, non-Hodgkin's lymphoma and leukemia, and increased pre-existing bladder cancer. Men showed statistically significant increases in all cancer, melanoma, and kidney cancers, and mouth and throat cancers. Multivariate analysis incorporating available risk factor data did not weaken positive associations with BCSC except slightly for melanoma and for bladder cancer in women. Other previously reported associations were not confirmed. Conclusion: Periodic skin examinations appear well justified after removal of BCSC to detect new skin cancers including melanoma. Given the relatively weak, unexplained associations of BCSC with internal cancers, the costs vs. benefits of extra efforts to detect the latter still need to be determined.     

Pooled analysis of 3 European case-control studies of epithelial ovarian cancer: III. Oral contraceptive use

The relationship between use of oral contraceptives (OCs) and other contraceptive methods and the risk of ovarian cancer was examined in a combined analysis of 3 hospital-based case-control studies conducted in Italy, the United Kingdom, and Greece, for a total of 971 ovarian cancer cases and 2,258 controls under age 65. Compared with never-users, the combined multivariate relative risk (RR) for ever-users was 0.6 (95% confidence interval, CI = 0.4-0.8) and the estimates were consistent in the 3 datasets. The protection was also similar across strata of age and parity. Considering various measures of OC use, available in the Italian and British datasets only, the protection conveyed on ovarian cancer risk increased with the duration of use and persisted in the medium-long period: the RR in women reporting their last OC use greater than or equal to 15 years prior to diagnosis was 0.5 (95% CI = 0.2-1.0). The risks in ever-users were appreciably lower in those women who reported their first OC use before 25 years of age (RR = 0.3 for first use before age 25, 0.8 for first use at age 25-34 and 0.7 at 35 years or after). Such findings emerged similarly from Italian and British data. This combined analysis, besides offering further quantitative estimates of the protective effects of OCs on ovarian cancer risk in European populations, provides useful insights into the time pattern of the relationship between OC use and ovarian carcinogenesis, suggesting that the protection persists for 15 years or more after cessation of use and may be larger for use at younger age.     

Oral contraceptives and colorectal cancer risk: a meta-analysis

Several studies have suggested an inverse association between use of combined oral contraceptives (OC) and the risk of colorectal cancer and here we present a meta-analysis of published studies. Articles considered were epidemiological studies published as full papers in English up to June 2000 that included quantitative information on OC use. The pooled relative risks (RR) of colorectal cancer for ever OC use from the 8 case-control studies was 0.81 (95% confidence interval (CI): 0.69-0.94), and the pooled estimate from the 4 cohort studies was 0.84 (95% CI: 0.72-0.97). The pooled estimate from all studies combined was 0.82 (95% CI: 0.74-0.92), without apparent heterogeneity. Duration of use was not associated with a decrease in risk, but there was some indication that the apparent protection was stronger for women who had used OCs more recently (RR = 0.46; 95% CI: 0.30-0.71). A better understanding of this potential relation may help informed choice of contraception.