Use of exogenous hormones by women and lung cancer: evidence from the Royal College of General Practitioners' Oral Contraception Study

OBJECTIVE: The objective of this study was to assess the risk of lung cancer among women who have used oral contraception or hormone replacement therapy (HRT), especially those exposed to both classes of exogenous hormones. DESIGN: This study is a nested case-control one using prospectively collected data from the Royal College of General Practitioners' Oral Contraception Study (OCS). The 162 case patients were women with a diagnosis of lung cancer recorded on the OCS database by August 2004. Each case patient was matched with 3 control subjects who were free of the disease at the time of the case patient's diagnosis, of similar age and with similar length of follow-up in the OCS. RESULTS: Compared with never use, current use of oral contraception was associated with a statistically nonsignificant reduced risk of lung cancer, with an adjusted odds ratio (OR) of 0.47 and a 95% confidence interval (CI) of 0.08-2.95 (OR=0.86 and 95% CI=0.50-1.48 for former use; OR=0.84 and 95% CI=0.49-1.43 for ever use). Similar comparisons for HRT were current use (OR=1.21, 95% CI=0.23-6.37), former use (OR=0.62, 95% CI=0.23-1.68) and ever use (OR=0.71, 95% CI=0.28-1.78). The OR among women who had used both classes of hormones was 0.53 (95% CI=0.16-1.72), as compared with those who had used neither. CONCLUSIONS: Our results are compatible with findings from other studies that suggest that oral contraceptives may reduce the risk of lung cancer. Evidence for a beneficial effect of HRT is less convincing. Further study is needed to determine how long any benefit lasts and whether it is stronger in women exposed to both classes of exogenous hormones. The small number of events occurring in this very large cohort, however, shows that any public health benefit is likely to be marginal.     

Age and menopausal effects of hormonal birth control and hormone replacement therapy in relation to breast cancer risk

It is unclear whether breast cancer risk varies by age and menopausal status in relation to use of hormonal birth control (HBC) and hormone replacement therapy (HRT), taken singly or cumulatively. The authors utilized data from 1,478 cases and 1,493 controls aged 20-98 years with known menopausal status, who had participated in a population-based, case-control study conducted on Long Island during 1996-1997. Exogenous hormone use over the lifecourse was assessed by use of memory aids. The authors examined associations among women in these subgroups: premenopausal (n = 968), postmenopausal <65 years (n = 1,045), and postmenopausal > or = 65 years (n = 958). Among premenopausal women, risk was increased for ever use of HBC (odds ratio (OR) = 1.37, 95% confidence interval (CI): 1.04, 1.81) or HRT (OR = 1.81, 95% CI: 1.17, 2.81) and was pronounced among women reporting use of both HBC and HRT (OR = 2.59, 95% CI: 1.50, 4.46), long-term HRT use (OR = 3.93, 95% CI: 1.43, 10.84), or estrogen-plus-progestin therapy (OR = 3.51, 95% CI: 1.45, 8.49). There was no effect of ever HBC use among postmenopausal women aged less than 65 years, but risk was modestly elevated for more than 5 years of HRT use (OR = 1.41, 95% CI: 1.00, 1.99). Among postmenopausal women aged 65 years or more, odds ratios for HBC or HRT use were around the null. These results emphasize that timing of exogenous hormone use is important. Women who used these hormones before menopause had elevated risks, but the harmful effects began to decline with age after menopause.     

Hormonal factors and risk of lung cancer among women?

BACKGROUND: Gender differences in the histological distribution of lung carcinoma and a possibly greater susceptibility of women than men to tobacco carcinogens, suggest a possible influence of sex-specific hormones. This study examines endocrine factors and risk of lung cancer among women by smoking status and histology. METHODS: We used data of a case-control study on lung cancer conducted from 1990 to 1996 in Germany, including 811 histologically confirmed female cases and 912 female population controls. Information on various menstrual and reproductive factors, use of oral contraceptives (OC), hormone replacement therapy (HRT), and smoking was gathered through personal interviews using a structured questionnaire. Odds ratios (OR) and 95% CI adjusted for age, region, smoking, and education were calculated via logistic regression. RESULTS: A reduction in lung cancer risk was observed with the use of OC (OR = 0.69; 95% CI: 0.51-0.92), but no trend in risk with increasing duration of use, age at first use, or calendar year of first use was present. A history of HRT was associated with a reduced risk (OR = 0.83; 95% CI: 0.64-1.09), particularly after long duration (>/=7 years) (OR = 0.59; 95% CI: 0.37-0.93). No clear association was found with regard to age at menarche, length of menstrual cycle, number of live-births, and age at menopause. Overall results did not differ much by histological cell subtype. The reduction in lung cancer risk associated with the use of exogenous hormones was primarily seen among smoking women. CONCLUSIONS: Our data provide evidence for a possible role of hormonal factors in the aetiology of lung cancer in women.     

Fibroadenoma and the use of exogenous hormones. A case-control study

The association between fibroadenoma and the use of exogenous hormones in women aged 18-74 years was examined in a case-control study conducted in Connecticut during 1979-1981. The study population included 251 women with biopsy-confirmed fibroadenoma and 1,081 control women drawn from inpatient and outpatient general surgical services of five Connecticut hospitals. Among women under age 45 years, oral contraceptive use was negatively associated with the occurrence of fibroadenoma (age-adjusted odds ratio (OR) = 0.57, 95% confidence interval (CI) = 0.42-0.79). The odds ratio for women over age 45 years who had ever used oral contraceptives was 1.65 (95% CI = 0.58-4.68). Women over age 45 years who had ever used replacement estrogens had an elevated odds ratio for fibroadenoma (OR = 2.83, 95% CI = 1.21-6.60). The data suggest either that the effects of exogenous hormones may differ by age, or that the changing composition of exogenous hormones has brought about different associations depending upon the cohort of women.     

Oral contraceptives, other methods of contraception, and risk reduction for ovarian cancer

Oral contraceptives reduce the risk of ovarian cancer, but the impact of other methods of contraception has not been fully explored. This population-based, case-control study involved women 20-69 years of age who had ever had intercourse. We compared cases with a recent diagnosis of ovarian cancer (N = 727) with community controls (N = 1,360). All methods of contraception evaluated were associated with a reduced risk for ovarian cancer. After adjustment for age, race, pregnancies, and family history of ovarian cancer, the odds ratios for ever-use of each method as compared with never-use were: oral contraceptives for contraception, 0.6 (95% confidence interval = 0.5-0.8); intrauterine device, 0.8 (95% confidence interval = 0.6-1.0); barrier methods, 0.8 (95% confidence interval = 0.6-0.9); tubal ligation, 0.5 (95% confidence interval 0.4-0.7); and vasectomy, 0.8 (95% confidence interval = 0.6-1.1). Nulligravid women were not protected by any of these contraceptive methods. Multigravid women, however, were protected by all methods. We conclude that various methods of contraception reduce ovarian cancer risk. This effect does not appear to result from contraceptive use being a nonspecific marker of fertility. The results imply mechanisms other than hormonal or ovulatory by which ovarian cancer risk is reduced.     

Incidence of thyroid cancer in women in relation to reproductive and hormonal factors

Female residents of western Washington state aged 18-80 years in whom thyroid cancer was diagnosed between January 1974 and December 1979 were interviewed concerning their reproductive histories and their prior use of exogenous estrogens. Their responses were compared with those of a sample of women from the same population, individually matched to cases on telephone prefix. Use of each of several estrogen-containing preparations was associated with a small increased risk of thyroid cancer; parous women who had ever used a lactation suppressant had 1.7 times the risk of parous nonusers (95% confidence interval, 1.1-2.8); ever users of oral contraceptives had 1.6 times the risk of never users (95% confidence interval, 0.98-2.5); and ever users of postmenopausal estrogens had 1.4 times the risk of never users (95% confidence interval, 0.89-2.3). Among the low risk group of women, i.e., those who had never undergone radiation therapy and who had never had a goiter, a history of one or more pregnancies was also associated with a small increase in the risk of thyroid cancer (relative risk = 1.8, 95% confidence interval, 1.1-3.1). However, no increase in risk with increasing duration of use of oral contraceptives or menopausal estrogens or with increasing number of pregnancies was noted. While pregnancy and use of exogenous estrogens have an impact on the production of thyroid-stimulating hormone, their effect on the incidence of thyroid carcinoma, if present at all, appears to be small.     

Factors Modifying the Association Between Hormone-Replacement Therapy and Breast Cancer Risk

Objectives: Hormone-replacement therapy (HRT) is an established risk factor for breast cancer. HRT users are different from non-users with respect to socio-economic and other characteristics. There may be women where the HRT-related risk could be modulated by other factors.Methods: We conducted a population-based case–control study with 688 breast cancer cases and 724 controls to characterize HRT users and to estimate odds ratios (OR) and 95% confidence intervals (CI) for HRT use and potentially risk modifying factors. Results: In women aged 50 years and older, 58% of controls and 61% of cases ever used HRT. Among women in natural menopause, HRT use for 10 years and more years was associated with an increased breast cancer risk (OR 1.79, 95% CI, 1.12–2.87), but not among women in surgical menopause (OR 0.61, 95% CI, 0.09–4.17). In the subgroup of women with a positive family history of breast cancer, each year of HRT use increased the risk by 1.22 (95% CI, 1.02–1.47). Another subgroup comprised women with at least 10 diagnostic mammograms (OR 4.04, 95% CI, 1.10–14.81 for using HRT 10 or more years).Conclusions: Long-term HRT use was associated with a breast cancer risk in women with natural menopause. Our findings suggest that this risk may be increased in women with a positive family history of breast cancer and in women who received frequent diagnostic mammographic screens.     

Hormone replacement therapy and hip fracture risk: effect modification by tobacco smoking, alcohol intake, physical activity, and body mass index

The authors prospectively studied the overall effect of hormone replacement therapy (HRT) on hip fracture risk and the effect modification by behavioral habits and body mass index. A total of 6,159 postmenopausal women from the Copenhagen Center for Prospective Population Studies, Copenhagen, Denmark, with initial examination in 1976-1978 were followed until 1993. During follow-up 363 hip fractures were identified. Women who reported current use of HRT had a lower risk of hip fracture as compared with women who were nonusers (relative risk (RR) = 0.71; 95 percent confidence interval (CI): 0.50, 1.01). Use of HRT was associated with a lower risk of hip fracture in former (RR = 0.55; 95 percent CI: 0.22, 1.37) and current (RR = 0.61; 95 percent CI: 0.38, 0.99) smokers but not in never smokers (RR = 1.10; 95 percent CI: 0.60, 2.03). HRT was also associated with lower risk of hip fracture among alcohol drinkers (RR = 0.36; 95 percent CI: 0.14, 0.90) and among sedentary women (RR = 0.42; 95 percent CI: 0.18, 0.98) but not among nondrinkers (RR = 0.99; 95 percent CI: 0.61, 1.61) and physically active women (RR = 0.92; 95 percent CI: 0.42, 2.04). There was no evidence of interaction between use of HRT and body mass index. In conclusion, the protective effect of HRT on hip fracture appears to be strongest in women who ever smoked, in women who drink alcohol, and in women who are sedentary. The results suggest that history of behavioral habits offers important information concerning the probable degree of protection against hip fracture afforded by HRT.     

Risk factors for invasive epithelial ovarian cancer: results from a Swedish case-control study

This case-control study evaluated reproductive and other factors in relation to epithelial ovarian cancer (EOC) risk. Between 1993 and 1995, the authors recruited 655 EOC cases and 3,899 population controls aged 50-74 years who were born in and residents of Sweden. Data were collected through mailed questionnaires. Odds ratios were estimated by unconditional logistic regression. Parity reduced EOC risk (odds ratio = 0.61, 95% confidence interval (CI): 0.46, 0.81) for uniparous compared with nulliparous women. The risk of EOC decreased with incomplete pregnancies, early menopausal age, late age at first birth, and unilateral oophorectomy; increased with family history of ovarian cancer; and was not associated with menarcheal age, lactation, irregular menses, and menopausal symptoms. Histology-specific odds ratios of EOC for ever compared with never users of oral contraceptives were: serous, 0.56 (95% CI: 0.42, 0.74); mucinous, 1.96 (95% CI: 1.04, 3.68); endometrioid, 0.71 (95% CI: 0.49, 1.03); clear cell, 0.66 (95% CI: 0.31, 1.43); and all EOCs, 0.73 (95% CI: 0.59, 0.90). Prolonged oral contraceptive use reduced EOC risk, with persistent protection up to 25 years after the last use. Ever use of hormone replacement therapy increased EOC risk (odds ratio = 1.41, 95% CI: 1.15, 1.72). Among etiologic hypotheses, the retrograde transportation hypothesis accommodates most epidemiologic findings concerning EOC risk.     

Pregnancy, breast feeding, and oral contraceptives and the risk of epithelial ovarian cancer

To quantify the effects of cumulative months of pregnancy, breast feeding, and oral contraceptive use on the risk of developing epithelial ovarian cancer, the authors used data collected for the Cancer and Steroid Hormone Study--a multicenter, population-based, case-control study. Detailed reproductive histories were obtained from 436 women aged 20-54 with epithelial ovarian cancer newly diagnosed between December 1980 and December 1982, and from 3833 women aged 20-54 selected at random from the same geographic areas. Estimated relative risks of epithelial ovarian cancer were 0.6 (95% confidence interval (CI) 0.5-0.8) for women who had ever been pregnant, 0.6 (95% CI 0.5-0.8) for women who had ever breast fed, and 0.5 (95% CI 0.5-0.7) for women who had ever used oral contraceptives. Logistic regression analysis revealed a strong trend in decreasing risk of epithelial ovarian cancer with increasing cumulative months of pregnancy; this effect was less pronounced in women aged 50-54 than in younger women. In contrast, a marked reduction in risk was associated with ever having breast fed or used oral contraceptives, while the decrease in risk from additional months of either of these exposures was less than that for pregnancy.     

Interactions of familial and hormonal risk factors for large bowel cancer in women.

BACKGROUND: Family history of colorectal cancer has been consistently associated with an increased personal risk of this disease. Since evidence suggests that hormones are related to colon cancer risk in women, the effect of family history on large bowel incidence may be modified according to endogenous and exogenous hormone levels. METHODS: We analysed data from a population-based case-control study of female colorectal cancer to evaluate family history and cancer risk. Cases (n = 702) were female residents of Wisconsin with a new diagnosis of colorectal cancer, identified through a statewide tumour registry. Controls (n = 2274) were randomly selected from lists of licensed drivers and from rosters of Medicare beneficiaries. All relative risks (RR) were adjusted for age, body mass index, smoking and alcohol history, education, and use of hormone replacement therapy. RESULTS: Compared with women who reported no history of cancer in a first degree relative, women with a family history had an RR of 2.07 (95% confidence interval [CI]: 1.60-2.68). Regardless of which parent was affected, risks were increased about twofold, while sibling history was associated with about a 50% increase in risk. Risk was greater if more than one family member was affected (RR 3.65, 95% CI: 1.81-7.37). The association between family history and risk was stronger for colon cancer than for rectal cancer. There were no indications that exogenous hormonal factors, notably hormone replacement use, modified these risks. There was a suggestion that high parity attenuated the risks associated with family history (P = 0.07). CONCLUSIONS: These results confirm that family history of colorectal cancer is associated with a doubling of risk for large bowel cancer in women; some histories were associated with greater risk. This relation was not substantially different among subgroups of women with varying exogenous and endogenous hormone exposures.     

Menopausal hormones and breast cancer in a biracial population

OBJECTIVES: This study examined the association between menopausal hormones and breast cancer in a biracial population. METHODS: Logistic regression was used to calculate odds ratios for breast cancer associated with hormone use among 397 cases and 425 controls, all menopausal women. RESULTS: Odds ratios for ever use of hormones were 0.8 (95% confidence interval [CI] = 0.5, 1.2) for White women and 0.7 (95% CI = 0.4, 1.2) for Black women. Risk was not increased with longer duration of use or more recent use. CONCLUSIONS: Breast cancer risk was not increased among White or Black women who used menopausal hormones, despite patterns of use varying considerably between races.     

Dietary intakes of selected nutrients and food groups and risk of cervical cancer

We investigated the relationships between intakes of selected dietary nutrients and food groups and risk of cervical cancer in a hospital-based, case-control study including 239 cases diagnosed with squamous cell carcinoma of the cervix and 979 hospital patients with nonneoplastic diagnoses who completed a self-administered questionnaire between 1982 and 1998 at Roswell Park Cancer Institute. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression adjusting for age, education, smoking status, use of oral contraceptives, barrier contraceptives and spermicides, family history of cervical cancer, year questionnaire completed, and energy intake. Significant reductions in risk of approximately 40-60% were observed for women in the highest vs. lowest tertiles of dietary fiber (OR=0.59, 95% CI=0.37-0.94), vitamin C (OR=0.52, 95% CI=0.33-0.80), vitamin E (OR=0.44, 95% CI=0.27-0.72), vitamin A (OR=0.47, 95% CI=0.30-0.73), alpha-carotene (OR=0.41, 95% CI=0.27-0.63), beta-carotene (OR=0.44, 95% CI=0.29-0.68), lutein (OR=0.51, 95% CI=0.33-0.79), folate (OR=0.55, 95% CI=0.34-0.88), and total fruit and vegetable intake (OR=0.52, 95% CI=0.34-0.77). Our findings suggest that a diet rich in plant-based nutrients may be important in reducing the risk of cervical cancer.     

Dietary boron and hormone replacement therapy as risk factors for lung cancer in women

Hormone replacement therapy (HRT) may reduce lung cancer risk. Dietary boron may have actions similar to those of HRT; however, no previous study has reported the associations between dietary boron intake and lung cancer risk or the joint effects of boron intake and HRT use on lung cancer risk. The authors examined the associations between boron intake and the joint effects of boron intake and HRT on lung cancer risk in women. In an ongoing case-control study in Houston, Texas (July 1995 through April 2005, end date for this analysis), 763 women were diagnosed with lung cancer, and 838 were matched healthy controls with data on both diet and HRT. Multiple logistic regression analyses were conducted to assess the associations between dietary boron and HRT with lung cancer risk. After adjustment for potential confounders, the odds ratios for lung cancer with decreasing quartiles of dietary boron intake were 1.0, 1.39 (95% confidence interval (CI): 1.02, 1.90), 1.64 (95% CI: 1.20, 2.24), and 1.95 (95% CI: 1.42, 2.68) mg/day, respectively, for all women (p(trend) < 0.0001). In joint-effects analyses, compared with women with high dietary boron intake who used HRT, the odds ratio for lung cancer for low dietary boron intake and no HRT use was 2.07 (95% CI: 1.53, 2.81). Boron intake was inversely associated with lung cancer in women, whereas women who consumed low boron and did not use HRT were at substantial increased odds.     

Menopausal hormone therapy and risks of colorectal adenomas and cancers in the French E3N prospective cohort: true associations or bias?

Menopausal hormone therapy (MHT) use has been quite consistently associated with a decreased colorectal cancer risk; however, data regarding adenomas, types of MHT, or tumour site are limited. We investigated associations between MHT use and colorectal adenoma and cancer risks within the prospective E3N cohort study. In the adenoma study, we analyzed the 13,402 postmenopausal women who underwent a colonoscopy during follow-up (1993-2002), including 1,109 who were diagnosed a first colorectal adenoma. In the cancer study, 525 out of 77,375 postmenopausal women developed a colorectal cancer as the first malignant tumour during follow-up (1992-2008). Ever use of MHT was not significantly associated with colorectal adenoma risk [Hazard Ratio (HR) = 1.13, 95 % Confidence Interval (CI) = 0.99, 1.29], nor with colorectal cancer risk (HR = 0.86, 95 % CI = 0.71, 1.04). However, ever use of estrogens alone was associated with risks of colorectal adenoma and cancer in opposite directions (HR = 1.22, 95 % CI = 1.05, 1.41 and HR = 0.72, 95 % CI = 0.56, 0.94 respectively). Associations were strongest for non-advanced, and for left colon adenomas. Duration, recency of use, type of progestagen or route of estrogen administration were not associated with colorectal tumour risk, nor was the use of estrogen-progestagen MHT. The association between estrogens alone and colorectal cancer risk was only observed in women with previous colonoscopy(ies), but the P value of the interaction test between estrogens alone use and history of colonoscopy was 0.06. Our data suggest a complex relationship between MHT use, colorectal tumour risk and screening strategies, which deserves further investigations in other settings.     

女性激素替代治疗、口服避孕药与女性肺癌关系的Meta分析

目的探讨女性激素替代治疗(HRT)与口服避孕药(OCs)对女性肺癌的影响。方法搜索Medline等计算机数据库,系统收集相关文献。采用固定模型或随机效应模型(研究结果存在异质性)计算合并OR。结果纳入Meta分析的文献共12篇,其中3篇为队列研究,9篇为病例对照研究。Meta分析HRT与肺癌合并OR值为0.88(95%CI:0.77～1.01)。按是否吸烟进行分层分析,吸烟者与非吸烟者中HRT的合并OR值分别为0.76(95%CI:0.61～0.95)和0.78(95%CI:0.64～0.95)。口服避孕药与女性肺癌无统计学关联(OR=0.95;95%CI:0.83～1.20)。结论HRT可能降低女性肺癌发生的危险度,其结果还需要进一步深入研究来验证。     

Are patients with skin cancer at lower risk of developing colorectal or breast cancer?

Ultraviolet exposure may reduce the risk of colorectal and breast cancer as the result of rising vitamin D levels. Because skin cancer is positively related to sun exposure, the authors hypothesized a lower incidence of breast and colorectal cancer after skin cancer diagnosis. They analyzed the incidence of colorectal and breast cancer diagnosed from 1972 to 2002 among 26,916 Netherlands skin cancer patients (4,089 squamous cell carcinoma (SCC), 19,319 basal cell carcinoma (BCC), and 3,508 cutaneous malignant melanoma (CMM)). Standardized incidence ratios were calculated. A markedly decreased risk of colorectal cancer was found for subgroups supposedly associated with the highest accumulated sun exposure: men (standardized incidence ratio (SIR) = 0.83, 95% confidence interval (CI): 0.71, 0.97); patients with SCC (SIR = 0.64, 95% CI: 0.43, 0.93); older patients at SCC diagnosis (SIR = 0.59, 95% CI: 0.37, 0.88); and patients with a SCC or BCC lesion on the head and neck area (SIR = 0.59, 95% CI: 0.36, 0.92 for SCC and SIR = 0.78, 95% CI: 0.63, 0.97 for BCC). Patients with CMM exhibited an increased risk of breast cancer, especially advanced breast cancer (SIR = 2.20, 95% CI: 1.10, 3.94) and older patients at CMM diagnosis (SIR = 1.87, 95% CI: 1.14, 2.89). Study results suggest a beneficial effect of continuous sun exposure against colorectal cancer. The higher risk of breast cancer among CMM patients may be related to socioeconomic class, both being more common in the affluent group.     

Case-control study of postmenopausal hormone replacement therapy and endometrial cancer

This study evaluated recent inconsistent findings that adding progestins to postmenopausal estrogen replacement therapy protects against endometrial cancer. Using a population-based case-control study, the authors compared 511 endometrial cancer cases aged 50-79 years in the Philadelphia, Pennsylvania, region during 1999-2002 with 1,412 random-digit-dialing controls regarding postmenopausal hormone replacement therapy (HRT) use. Telephone interviews were performed with memory aids mailed in advance. An increased risk of endometrial cancer was observed among postmenopausal women using only unopposed estrogen for 3 or more years, compared with women who never used HRT (adjusted odds ratio = 3.4, 95% confidence interval (CI): 1.4, 8.3). Using combination HRT (of any duration) was associated with a substantial reduction in risk (odds ratio = 0.8, 95% CI: 0.6, 1.1). Comparing women using only combined estrogen and progestin for 3 or more years with women using only unopposed estrogen for 3 or more years, the authors found that the adjusted odds ratio was 0.2 (95% CI: 0.1, 0.6). Long-term use of unopposed estrogen is associated with increased risk for endometrial cancer, whereas combined estrogen plus progestin hormone therapy is not. Thus, if HRT is to be used in women with an intact uterus, this study confirms the benefit of adding progestins to the regimen.     

Hormone replacement therapy is not safe for breast cancer survivors

QuestionIs hormone replacement therapy safe for women with previous breast cancer?Study designRandomised controlled trial (interim analysis).Main resultsIn 345 women surviving breast cancer, there were more new breast cancer events in women taking HRT for menopausal symptoms compared with women receiving symptomatic treatment without hormones at a median of 2 years follow-up (absolute risk for new breast cancer: 26/174 [14%] with HRT vs 8/171 [5%] with no HRT; relative hazard 3.5, 95% CI 1.5 to 8.1).Authors’ conclusionsIn women surving breast cancer, those who received HRT for menopausal symptoms were at a higher risk of developing new breast cancers compared with those who received symptomatic treatment without hormones. These findings led to the termination of the trial.     

Infertility and breast cancer: a population-based case-control study

To investigate whether a history of infertility affects a woman's risk of developing breast cancer, the authors analyzed case-control data collected between 1980 and 1982 as part of the Cancer and Steroid Hormone Study. The 4,730 cases were women aged 20-54 years with a first diagnosis of breast cancer ascertained from eight population-based cancer registries; the 4,688 controls were women randomly selected from the general population of these same eight areas. After controlling for age, age at first birth, and parity, the odds ratio (OR) for breast cancer associated with infertility was 1.01 (95% confidence interval (CI) 0.89-1.15) among gravid women. Controlling for age, the odds ratio was 0.82 (95% CI 0.59-1.14) among nulligravid women. Women who reported that the reason for their infertility was a problem with their ovaries had a risk similar to that for women without a history of infertility (OR = 0.75, 95% CI 0.48-1.24). Women whose physicians reported that the reason for their infertility was anovulation or Stein-Leventhal syndrome also had risks similar to those for women without a history of infertility (OR = 1.26 (95% CI 0.67-2.34) and OR = 1.13 (95% CI 0.46-2.78), respectively). Menopausal status, age at menarche, history of spontaneous abortions, drinking or smoking behavior, use of exogenous hormones, or family history of breast cancer did not appreciably alter the observed odds ratios. If infertility has an effect on breast cancer that is independent of age at first birth, then the effect is small.