Cancer of the breast and reproductive tract in relation to use of oral contraceptives

Combined oral contraceptive use before the first birth and epithelial ovarian cancer risk

Background:

Combined oral contraceptive (COC) use reduces epithelial ovarian cancer (EOC) risk. However, little is known about risk with COC use before the first full-term pregnancy (FFTP).

Methods:

This Canadian population-based case–control study (2001–2012) included 854 invasive cases/2139 controls aged ⩾40 years who were parous and had information on COC use. We estimated odds ratios (aORs) and 95% confidence intervals (CI) adjusted for study site, age, parity, breastfeeding, age at FFTP, familial breast/ovarian cancer, tubal ligation, and body mass.

Results:

Among parous women, per year of COC use exclusively before the FFTP was associated with a 9% risk reduction (95% CI=0.86–0.96). Results were similar for high-grade serous and endometrioid/clear cell EOC. In contrast, per year of use exclusively after the FFTP was not associated with risk (aOR=0.98, 95% CI=0.95–1.02).

Conclusions:

Combined oral contraceptive use before the FFTP may provide a risk reduction that remains for many years, informing possible prevention strategies.

Non-contraceptive benefits of oral contraceptives

BACKGROUND

There is increasing awareness of the opportunity that many contraceptive interventions may provide for additional health benefits. However, treatment of medical problems with oral contraceptives (OCs) is often an 'off-label' practice.

OBJECTIVE

The aim of this review is to summarize available data on non-contraceptive benefits of OCs.

METHODS

Review of the literature.

RESULTS

OCs have been shown to reduce the risk of ovarian, endometrial, and colorectal cancer. It has been suggested that OCs may be used in treatment of endometriosis, menorrhagia, and uterine leiomyomas. Pelvic inflammatory disease, dysmenorrhea, premenstrual syndrome, and acne have been shown to improve under OCs.

CONCLUSION

OCs are important for global and female health. Besides contraception, non-contraceptive effects of OCs are evidence based, well established, and commonly used in clinical practice.

Contraceptive needs of the perimenopausal woman

Although there are many definitions of the perimenopause, all include the concept of transition from physiologic ovulatory menstrual cycles to hyperestrogenic anovulation and ultimately to hypoestrogenic ovarian shutdown. With this comes a transition from childbearing, and its requirement for contraception, to the infertility of menopause. There is no contraceptive method that is contraindicated merely by age. The contraceptive needs of the perimenopausal woman, however, may be better suited to some methods over others. This article explores various methods of contraception for the perimenopausal woman, including female sterilization, barrier methods, intrauterine devices, injectables, implants, and oral contraceptives.

Divergent effects of retinoic acids on the expression of ERalpha and 17beta-hydroxysteroid dehydrogenase type 2 in endometrial carcinoma cells (RL 95-2)

The effects of E2 are dependent on ERs and local E2 concentration in target cells. Modulation of intracellular E2 concentration involves the action of 17beta-hydroxysteroid dehydrogenase (17HSD) type 2, the enzyme converting E2 to estrone. In the present study, the influence of RAs on the growth of endometrial cancer cell line RL 95-2 as well as the expression of ERs and 17HSD type 2 have been investigated. It was found that RAs repress the growth of RL 95-2 cells, which express all subtypes of RXR and RAR, as examined by RT-PCR. Also, quantitative RT-PCR analysis showed that both ERalpha and ERbeta are present in RL 95-2 cells, and Western blot assay further revealed that ERalpha expression was decreased by all trans-RA treatment. In contrast, RAs induced 17HSD type 2 mRNA expression in a dose- and time-dependent fashion. This stimulatory effect was also detected at the level of in vivo oxidative 17HSD activity in cultured cells. On the other hand, the abundance of 17HSD type 2 mRNA was not altered by RAs in cultured normal epithelial cells isolated from human early- and late-secretory endometrium. The data indicate that RAs have an inhibitory effect on the growth of RL 95-2 cells and a cross-talk with the estrogen pathway in estrogen-responsive endometrial cancer cells.

Bias and causal associations in observational research

Readers of medical literature need to consider two types of validity, internal and external. Internal validity means that the study measured what it set out to; external validity is the ability to generalise from the study to the reader's patients. With respect to internal validity, selection bias, information bias, and confounding are present to some degree in all observational research. Selection bias stems from an absence of comparability between groups being studied. Information bias results from incorrect determination of exposure, outcome, or both. The effect of information bias depends on its type. If information is gathered differently for one group than for another, bias results. By contrast, non-differential misclassification tends to obscure real differences. Confounding is a mixing or blurring of effects: a researcher attempts to relate an exposure to an outcome but actually measures the effect of a third factor (the confounding variable). Confounding can be controlled in several ways: restriction, matching, stratification, and more sophisticated multivariate techniques. If a reader cannot explain away study results on the basis of selection, information, or confounding bias, then chance might be another explanation. Chance should be examined last, however, since these biases can account for highly significant, though bogus results. Differentiation between spurious, indirect, and causal associations can be difficult. Criteria such as temporal sequence, strength and consistency of an association, and evidence of a dose-response effect lend support to a causal link.

Evaluating the safety of medicines, with particular reference to contraception

Toxicological studies and clinical trials cannot be expected to predict all important adverse effects of medicines and contraceptives. Post-marketing surveillance is essentially an epidemiological task that involves detecting associations between drugs and events. The first alerts about drug safety problems have often come from case reports, but epidemiological studies are needed to confirm adverse (or beneficial) effects and to provide quantitative information. This article illustrates methodological principles by considering three examples from the field of contraceptive safety: oral contraceptives and breast cancer, intrauterine contraception and pelvic inflammatory disease, and newer oral contraceptives and venous thromboembolism. Key issues that emerge include bias and confounding, the place of subgroup analyses, random error, and the use of computerized databases. In research on contraceptive and drug safety, conclusions usually need to be based on careful assessment of multiple observational studies.

Antitumor effect of GnRH agonist in epithelial ovarian cancer

OBJECTIVE

The effects of the gonadotropin releasing hormone (GnRH) agonist (D-Trp(6)) were examined in two human ovarian cancer cell lines and in severe combined immune deficiency (SCID) mice to evaluate its potential as a cytocidal, cytostatic, or differentiating antitumor agent.

METHODS

We treated the human ovarian cancer cell lines OVCAR-3 and SKOV-3 for 5 or 7 days and sex-matched SCID mice with GnRH agonist for 29 days. The antitumor effect of GnRH agonist were studied in various aspects. To confirm the antiproliferative effect, we used 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide colorimetric assay, in vitro, and a serial measurement of tumor growth in vivo. The disturbances of progression in the cell cycle and the changes of cyclin-dependent kinase 1 following treatment with GnRH agonist were evaluated with flow cytometric analysis in vitro. The induction of apoptosis following treatment with GnRH agonist was studied using in situ terminal deoxyribonucleotidyl transferase (Tdt) and further quantitated with ELISA in vitro. The presence of telomerase activity following treatment with GnRH agonist was measured by PCR-based telomeric repeat amplification protocol and ELISA detection in cell lines and xenografts in vitro and in vivo.

RESULTS

Continuous exposure of cell lines and xenografts to GnRH agonist resulted in growth inhibition of cancer cells in a dose- and time-dependent manner. In cultured cells, the GnRH agonist blocked cell cycle progression in G0/G1 phase and thus reduced the number of cells in S and G2/M phases. The phenomenon of apoptosis was documented in cultured cells treated with GnRH agonist by in situ Tdt assay. The frequency of apoptotic cells in the in situ Tdt assay was 5-6% compared with control, 4-5%. Apoptosis quantified by ELISA revealed a high incidence in cultured cells treated with GnRH agonist. The activities of telomerase in cell lines and xenografts were not decreased by GnRH agonist. There were not any significant changes of expression of CA-125 by flow cytometry and of the cellular morphology observed with light microscopy.

CONCLUSIONS

Our results indicate that the antiproliferative effect of GnRH agonist in epithelial ovarian cancer cells may be mainly attributed to cytostatic activities resulting in blocking of cell cycle progression in the G0/G1 phase and minimally related to the induction of apoptosis.

Hormonal interactions in ovarian cancer

According to the epidemiologic literature and the laboratory characterization of receptor content and molecular interactions, there is a relationship between the microenvironment of ovarian cancer and steroid hormones. Advances in our knowledge of the molecular-hormonal nature of ovarian cancer will help in designing a rationale for clinical trials in appropriate subsets of patients. However, currently, development of successful therapies and prevention strategies for women at risk remains a true challenge.

Breast cancer risk: perception versus reality

Evidence that breast cancer is hormonally mediated has fueled women's concern that use of oral contraceptives (OC) will increase their risk of developing the disease. A recent reanalysis of combined worldwide epidemiologic evidence regarding the relationship between breast cancer risk and use of combination OC provides reassurance that there is little or no association between OC use and breast cancer. Ten or more years after discontinuation of OC use, there is no difference in cumulative risk of breast cancer among OC ever-users and never-users. The risk of breast cancer diagnosis is slightly elevated in current OC users and remains slightly elevated until about 10 years after OC discontinuation. Once recency of use is taken into account, other characteristics have little additional effect. There is no increase in breast cancer risk with increasing dose or duration of OC use and no difference in risk related to type of estrogen or progestin used. Moreover, those breast cancers diagnosed in OC ever-users were found to be significantly more likely to be localized than those diagnosed in same-age never-users.

Prophylactic oophorectomy: a continuing controversy

Prophylactic oophorectomy remains a controversial issue among gynecological surgeons. A woman's history of hereditary ovarian cancer syndrome is currently considered the most important indication for prophylactic oophorectomy. This is because of the high risk of ovarian cancer developing in these women and the poor prognosis that is generally associated with ovarian cancer. The purpose of prophylactic oophorectomy in women with no family history of hereditary ovarian cancer syndrome who present for hysterectomy because of other gynecological indications is, however, less clear. The attitude of the patients toward removal of normal ovaries deserves special consideration when counseling for prophylactic oophorectomy in this group of women. Knowledge about the risk of ovarian cancer in the conserved ovaries, cancer phobia, possible psychological effects of prophylactic oophorectomy, and the need for long-term hormone replacement therapy if prophylactic oophorectomy is carried out, are all important considerations in the counseling process.

Is tubal sterilization associated with an increased risk of subsequent hysterectomy but a decreased risk of ovarian cancer? A review of recent literature

Recent epidemiologic studies have suggested that tubal sterilization (TS) may lead to an increased incidence of subsequent hysterectomy but a decreased risk of ovarian cancer. This review evaluates the nature and magnitude of these two relationships, which should be of great concern and interest to women, clinicians and the administrators of family planning programs. The positive relationship between TS and subsequent hysterectomy is more likely to be of a motivational rather than biological nature, and a considerable number of unnecessary hysterectomies after TS could be avoided by changing the attitudes of physicians and women. The inverse relationship between TS and ovarian cancer appears causal, although the exact biological mechanisms remain to be clarified. Theoretically, this non-contraceptive beneficial effect of TS could be used as a primary preventive measure to curb the incidence of the highly fatal ovarian cancer. However, a number of medical, ethical, and economic questions attending use of a generally irreversible contraceptive procedure as a preventive measure must first be answered. The issue of whether TS is associated with any long-term sequelae, and, if so, whether the association is of a cause-and-effect nature or a by-product of time passage and aging of the woman, should be addressed by well-designed studies.

Hormones and breast cancer

The exact nature of the association between hormones and the development of breast cancer remains uncertain. Studies of endogenous hormone levels and breast cancer suggest a possible role of estrogens and androgens in the cause of breast cancer. Numerous studies have been conducted to assess the risk of breast cancer among women exposed to exogenous hormones. Several studies of women who have used oral contraceptives have shown a twofold increase in risk for the onset of breast cancer at an early age associated with 10 years of oral contraceptive use. One of the largest studies, the Cancer and Steroid Hormone Study, found no association between breast cancer and oral contraceptive use for women up to the age of 54. A meta-analysis combining the results of 31 published studies of the association between hormone replacement therapy and breast cancer revealed no increased risk of breast cancer associated with ever-use (risk ratio [RR], 1.02; 95% confidence interval [CI], 0.93-1.12). Use of oral contraceptives for more than 10 years was associated with a small increased risk (RR, 1.23; 95% CI, 1.08-1.40), but few studies have examined very long term use. A recent study of pregnancy and breast cancer outcome found no adverse influence of pregnancy shortly before or after diagnosis of breast cancer on prognosis. The results of a wide range of studies should be considered when weighing the benefits and risks of hormone use among women at increased risk of breast cancer or with a history of breast cancer.

Contraception. A clinical review for the internist

Effective use of contraception allows couples to control their fertility and, in certain instances, is associated with important noncontraceptive benefits. Surgical sterilization offers safe, effective, and permanent contraception for women and men. Low-dose OCPs offer safe, effective contraception for most women able and willing to take pills consistently. In addition, their use confers a variety of important noncontraceptive benefits. The availability of long-acting progestin injectable and implantable methods has made highly effective and convenient birth control available for women who are not good pill takers as well as for those for whom contraceptive doses of estrogen are contraindicated. Barrier methods are readily available and provide protection against STDs; unfortunately, erratic use is all too often associated with inadequate contraceptive efficacy. IUDs offer convenient, highly effective contraception for appropriate candidates.

Coffee and cancer: a prospective study of 43,000 Norwegian men and women

Relationships between coffee drinking and cancer incidence were examined in a 10-year complete follow-up of 21,735 men and 21,238 women aged 35-54 years. The study population participated in a cardiovascular screening in three countries in Norway during 1977-82. Data on coffee and smoking habits were based on information from a self-administered questionnaire. There was no association between coffee consumption and overall risk of cancer. A positive association was found between coffee drinking and risk of lung cancer, also after adjustment for age, cigarette smoking, and county of residence. Residual confounding by cigarette smoking and other lifestyle factors cannot be ruled out. A negative association was found with cancer of buccal cavity and pharynx and with malignant melanoma in women. No significant associations were found between coffee drinking and incidence of cancer of the pancreas or the bladder.

Ovarian carcinoma. A review of the significance of familial risk factors and the role of prophylactic oophorectomy in cancer prevention

Women with a family history of ovarian cancer are at increased risk of ovarian cancer. Prophylactic oophorectomy (PO) remains the only effective method of ovarian cancer prevention. This study reviewed current data on the significance of family history and how prophylactic oophorectomy should be used in different risk groups. Approximately 7% of ovarian cancer patients have a positive family history of whom 3-9% may eventually manifest certain hereditary cancer syndromes. Women in direct genetic lineage of family cancer syndromes have up to a 50% lifetime risk of ovarian cancer. Because of the high risk, PO is indicated for women with familial cancer syndromes after childbearing or between the ages of 35-40 at the latest. The majority of women with a positive family history of ovarian cancer do not have one of the recognized syndromes. Women with one or two affected relatives have an increased lifetime risk of ovarian cancer from a baseline of 1.6 to 5-7%. This risk is not high enough to warrant PO for a large number of women. After being properly informed, the patient still chooses surgical prevention, she then receives PO. For women without a family history of ovarian cancer, the role of PO remains controversial. Assuming an annual incidence of 22,000 new cases of ovarian cancer, it is estimated that at least 1000 may be prevented if PO is diligently practiced during hysterectomy. Despite ovarian and breast cancer prevention, PO would lead to shorter life expectancy if estrogen therapy compliance were less than perfect. Thus, the decision on PO as a concurrent procedure should depend on the individual patient and her ability to comply with lifelong estrogen therapy.

Unanswered questions in hormonal replacement therapy

This review addresses many of the unanswered questions existing relative to the use of exogenous estrogens and progestins in postmenopausal women (PMW). The literature in the field is reviewed and summarized, with a particular effort to identify key questions of major concern. The effect of selection bias on conclusions reached from retrospective studies involving hormone replacement therapy (HRT) has not been examined. Less is actually known about the effects of progestins than estrogens. Many of the endocrine changes that occur with aging remain poorly defined. Effects of estrogens and progestins on the breast and on breast cancer are unclear. Estrogens have recognized beneficial effects and progestins have detrimental effects on lipoprotein metabolism. Estrogens also have direct effects on the vasculature and may impact on cardiovascular risk in other ways. Although estrogens are the only agents known to eliminate hot flushes, the mechanism by which flushes arise is not known. Estrogens may have ameliorating effects on mood and behavior and may improve dementia, but research in this area has been limited to date. Lastly, the preferred estrogens and progestins, their dosages and routes of administration, remain to be more completely defined.

Animal toxicity studies performed for risk assessment of the once-a-month injectable contraceptive Mesigyna

Results from toxicity studies performed for risk assessment of the combined injectable hormonal preparation Mesigyna are reviewed. Both components of Mesigyna, i.e., estradiol valerate (E2Val) and norethisterone enanthate (NET-EN), have been thoroughly investigated as individual compounds and some limited toxicity data have been obtained for the combination. Most findings which were gathered in these studies from different animal species occurred in the gonads, accessory genital and endocrine organs and can be related to the known species-specific pharmacological activity of a typical estrogen or progestin, respectively. No additional or unexpected information which might indicate a possible estrogen/progestin interaction was gained from the administration of the combined preparation to animals. Based on the results from toxicity testing, there were no objections to the long-term therapeutic use of Mesigyna for hormonal contraception. The predictive value of the effects (including the tumorigenicity) observed in the common laboratory animals with regard to human safety is critically discussed, taking the vast amount of previous experience with hormonal contraceptives into consideration. The conclusion is drawn that there is no animal model for safety assessment of sex steroids that adequately represents the human situation. Quantitative extrapolations from animal toxicity findings to humans, therefore, are not possible. Especially, the value of long-term studies and of toxicity studies on estrogen/progestin combinations is put into question. Like endocrine pharmacology studies, the toxicity studies with these steroid hormones are useful for the characterization of the possible endocrine pharmacological profile only.

Incidence trends for cancers of the breast, ovary, and corpus uteri in urban Shanghai, 1972-89

Incidence data from the Shanghai (People's Republic of China) Cancer Registry were used to assess the temporal trends of three major female cancers during 1972-89. Rates for cancers of the breast, corpus uteri and, to a lesser extent, ovary rose over the study period. The increases in breast and ovarian cancer were most pronounced among women under age 50, whereas those for corpus uteri cancer were restricted generally to those aged 55 to 69 years. When considered by cohort year of birth, risk of breast and ovarian cancers rose among women born since 1925 and 1935, respectively, but little evidence of cohort effect was apparent for corpus uteri cancer. Potential explanations for these patterns are explored.

Norgestrel and gestodene stimulate breast cancer cell growth through an oestrogen receptor mediated mechanism

There is great concern over the long-term influence of oral contraceptives on the development of breast cancer in women. Oestrogens are known to stimulate the growth of human breast cancer cells, and this laboratory has previously reported (Jeng & Jordan, 1991) that the 19-norprogestin norethindrone could stimulate the proliferation of MCF-7 human breast cancer cells. We studied the influence of the 19-norprogestins norgestrel and gestodene compared to a 'non' 19-norprogestin medroxyprogesterone acetate (MPA) on MCF-7 cell proliferation. The 19-norprogestins stimulated proliferation at a concentration of 10(-8) M, while MPA could not stimulate proliferation at concentrations as great as 3 x 10(-6) M. The stimulatory activity of the 19-norprogestins could be blocked by the antioestrogen ICI 164,384, but not by the antiprogestin RU486. Transfection studies with the reporter plasmids containing an oestrogen response element or progesterone response element (vitERE-CAT, pS2ERE-CAT, and PRE15-CAT) were performed to determine the intracellular action of norgestrel and gestodene. The 19-norprogestins stimulated the vitERE-CAT activity maximally at 10(-6) M, and this stimulation was inhibited by the addition of ICI 164,384. MPA did not stimulate vitERE-CAT activity. A single base pair alteration in the palindromic sequence of vitERE (resulting in the pS2ERE) led to a dramatic decrease in CAT expression by the 19-norprogestins, suggesting that the progestin activity required specific response element base sequencing. PRE15-CAT activity was stimulated by norgestrel, gestodene and MPA at concentrations well below growth stimulatory activity. This stimulation could be blocked by RU486. These studies suggest that the 19-norprogestins norgestrel and gestodene stimulate MCF-7 breast cancer cell growth by activating the oestrogen receptor.

Age-specific differences in the relationship between oral contraceptive use and breast cancer

BACKGROUND

Nearly all studies have suggested that the use of oral contraceptives (OC) is not associated with the aggregate risk of breast cancer diagnosed in women aged 20-54 years. Because of age-specific differences in the breast cancer-parity relationship and because of age-specific differences in other breast cancer risk factors, the Centers for Disease Control reexamined data from the Cancer and Steroid Hormone Study (CASH) to assess whether OC use has different effects on the risk of breast cancer at different ages of diagnosis.

METHODS

This population-based case-control study was designed to examine the relationship between the use of OC and the risk of breast, ovarian, and endometrial cancer. CASH was conducted in eight geographic areas in the United States during 1980-1982. All participants were interviewed at home with a pretested standardized questionnaire including a calendar of life events and a photograph book of all pills marketed in the United States.

RESULTS

We found that the relationship between the risk of breast cancer and OC use appeared to vary by the age at diagnosis. Among women aged 20-34 years at diagnosis or interview, those who had ever used OC had a slightly increased risk of breast cancer (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.0-2.1) compared with women of the same ages who had never used OC. Among these women, there were no trends of increasing or decreasing risk with any measure of OC use. Among women aged 35-44 years, there was no association between OC use and breast cancer. Among women aged 45-54 years, those who used OC had a slightly decreased risk of breast cancer (OR, 0.9; 95% CI, 0.8-1.0). Among these women, risk estimates decreased significantly with increasing time since first and last use.

CONCLUSIONS

Although the slightly increased risk estimates for the youngest women were compatible with findings by other investigators, the decreased risk estimates for the oldest women have not been described in as many studies. Available data provide no reasons to change prescribing practices or the use of OC that are related to the breast cancer risk.

Epidemiology of the noncontraceptive effects of oral contraceptives

Epidemiologic studies have made major contributions to our understanding of oral contraceptive safety. The findings of major studies of the risk of cardiovascular disease and neoplasia associated with oral contraceptive use are reviewed, with discussion of the many factors to be considered in the interpretation of conflicting results. Mortality data that were based on earlier oral contraceptive formulations, dosage, and usage patterns may not be relevant to current practices. Recent studies suggest that reduced doses of estrogens and progestins in current oral contraceptive formulations and better screening of patients have reduced the risks of cardiovascular disease associated with oral contraceptive use, with the most important exception being an increased risk among older women who smoke. While most epidemiologic studies demonstrate no overall association between oral contraceptives and breast cancer, unanswered questions remain concerning this relationship.

Oral contraceptives and gynecologic cancer: an update for the 1990s

The most recent statistical evidence confirms a protective effect of oral contraceptive use against ovarian and endometrial cancers. Studies of the association between oral contraceptive use and cervical cancer continue to be hampered by confounding factors; however, results suggest that the overall risk of invasive cervical neoplasia is not increased. Although the association between oral contraceptive use and breast cancer remains controversial, existing data strongly suggest that overall risk of breast cancer is not increased by the use of oral contraceptives. In most candidates for oral contraceptive use, the benefits greatly outweigh the risks.

Oral contraceptive use and the incidence of cervical intraepithelial neoplasia

OBJECTIVE

Our objective was to examine the relationship between oral contraceptive use and the incidence of cervical intraepithelial neoplasia.

STUDY DESIGN

In a prospective follow-up study of 6622 women participating in the Second Tromsö Study conducted in 1979 and 1980 in Tromsö, Norway, women aged 20 to 49 years answered a questionnaire regarding their smoking history, dietary habits, alcohol consumption, and oral contraceptive use. They were then followed for 10 years with data from the Pathology Registry of the University Hospital.

RESULTS

The age-adjusted incidence rate of cervical intraepithelial neoplasia was 897 per 100,000 person years among noncurrent and 1295 per 100,000 person years among current oral contraceptive users as of 1979. After adjusting for age, marital status, smoking, and frequency of alcohol intoxication the relative rate for current users was 1.5 (95% confidence interval 1.1 to 2.1), and the relative rate for past users was 1.4 (95% confidence interval 1.0 to 1.8), as compared with those who had never used oral contraceptives before 1979.

CONCLUSION

These findings support the hypothesis that the occurrence of cervical intraepithelial neoplasia is increased by oral contraceptive use.

The safety of oral contraceptives: epidemiologic insights from the first 30 years

Because oral contraceptives are used by tens of millions of healthy women, their safety for short-term and long-term use is an important issue that has been examined in a large number of epidemiologic studies. These studies have become more rigorous and have increased in size and analytic sophistication over the years. Although breast cancer remains the most important safety concern, the bulk of recent data suggests that oral contraceptives have no overall impact on a woman's risk of developing this disease. The results are less clear on the risk of cervical cancer and its precursors because of methodologic problems. However, the newer oral contraceptive formulations no longer appear to be associated with an increased risk of myocardial infarction or stroke.

Cyclical mastalgia as a marker of breast cancer susceptibility: results of a case-control study among French women

A matched case-control study in a population of urban, non-menopaused women living in Paris was performed between 1983 and 1985 to investigate the risk of breast cancer (BC) in relation to various factors with a particular interest in the effect of the use of oral contraceptive (OC) and the existence of cyclical mastalgia (CM). Two hundred and ten non-menopaused women, less than 45 years old, with newly diagnosed BC were compared to 210 controls from the same geographic area matched on year of birth, age, education level and age at first full term pregnancy (FFTP), when justified. The adjusted Relative Risk of BC (RRa) was significantly increased for a total duration of OC use longer than 72 months (RRa 2.80; 95% CI 1.56-5.01), as well as the RRa for OC use above 48 months before FFTP (3.26 95% CI 1.37-7.76) and, to a lesser extent, the RRa for OC use above 48 months after FFTP (2.02 95% CI 1.07-3.84) respectively. Adjustment was performed on familial history of BC, personal history of Benign Breast Disease (BBD), age at menarche. A previous history of cyclical mastalgia was found to be associated with an increased risk of BC. The significant increase remained after adjustment on the previously mentioned confounding factors and OC use: RRa 2.12; 95% CI (1.31-3.43). Under a precise definition related to the hormonal environment, mastalgia appear to be an interesting marker of breast cell susceptibility, the importance of which can only be validated by prospective studies.

Childbearing and use of oral contraceptives: impact of educational level. The Nordland Health Study

STUDY OBJECTIVE

The aim was to correlate the level of education to childbearing pattern and previous use of oral contraceptives in middle aged women.

DESIGN AND SETTING

The study was a cross sectional survey of 3608 women aged 40-42 years in a county in northern Norway and involved 72% of all women in the age bracket living in the county. Information about childbearing and use of oral contraceptives was obtained from a self administered questionnaire.

MAIN RESULTS

Level of education was inversely associated with parity and positively related to age at first and last birth, to the use of oral contraceptives at any time, and particularly to the use of oral contraceptives before the first birth.

CONCLUSIONS

Women with high level of education have relatively low parity and postpone childbearing by using oral contraceptives.

Oral contraceptives and breast cancer risk in Denmark

To evaluate the influence of oral contraceptives (OCs) on breast cancer risk, a population-based case-control study was conducted in Denmark. The study population included women aged less than 40 years (203 cases, diagnosed between 1 March 1983 and 31 August 1984, and 212 controls) and women aged 40-59 years (856 cases, diagnosed between 1 March 1983 and 29 February 1984, and 779 controls). Cases were identified from the nationwide clinical trial of the Danish Breast Co-operative Group and the Danish Cancer Registry. The control groups were age-stratified random samples of the general female population. Data on OC use and breast cancer risk factors were collected by self-administered questionnaires. In both age groups, no significant association was detected between breast cancer risk and duration, age at start, latency or recency of OC use. However, the data provided some limited support that OCs containing 50 micrograms or more oestrogen may be more harmful than pills with a lower oestrogen dose.

Worldwide variations in the lifetime probability of reproductive cancer in women: implications of best-case, worst-case, and likely-case assumptions about the effect of oral contraceptive use

Cancer incidence in countries representative of three patterns of reproductive cancer and age-specific mortality was used to estimate the effect of oral contraceptive use on the lifetime probability of reproductive cancer under three sets of assumptions about the effects of oral contraceptives. Under the set of assumptions considered likely, oral contraceptives were estimated to reduce or increase only slightly the lifetime probability of any reproductive cancer in each setting. Under worst-case assumptions, oral contraceptives were estimated to increase the lifetime probability of reproductive cancer only modestly in settings with low cancer rates and in settings with high rates of breast, ovarian, and endometrial cancer, but it might have a large impact on lifetime probability of reproductive cancer in settings with high cervical cancer rates. Under best-case assumptions, oral contraceptives were estimated to decrease the lifetime probability of reproductive cancer in each setting; this reduction was estimated to be greatest in settings where endometrial and ovarian cancer incidence are high.

Intracellular actions of gonadotropic and peptide hormones and the therapeutic value of GnRH-agonists in ovarian cancer

During the last two decades, considerable experimental evidence has been collected indicating that epithelial ovarian cancer might be gonadotropin dependent. LH and FSH receptors have been described in some of these tumors. The proliferation of ovarian cancer cells could be stimulated in vitro by gonadotropins. Suppression of endogenous LH and FSH secretion by GnRH-agonist treatment inhibited the growth of experimental or heterotransplanted ovarian cancers in various animal models. A number of recent phase II clinical trials have shown that the application of GnRH-agonists can lead to remission or stable disease in patients with relapsed advanced ovarian cancer. At present, prospective controlled clinical studies are being performed to assess the efficacy of GnRH-agonist treatment in addition to conventional surgical and cytostatic therapy in ovarian cancer in FIGO stages III and IV. Also, direct effects of GnRH analogues on ovarian cancer seem possible: a GnRH-like protein has been found in the human ovary. Our group discovered and partially characterized a specific GnRH-binding site (mol. wt 63.2 kDa) in ovarian cancer which is very similar to other human extrapituitary GnRH-binding sites of the low affinity, high capacity type, e.g. in breast cancer or the placenta. Recently, other groups have described also high affinity GnRH-agonist binding sites in ovarian cancer as well as in other extrapituitary tissues. First results from our laboratory indicate that the proliferation of certain ovarian cancer cell lines in vitro is reduced by both agonistic and antagonistic analogues of GnRH. Other authors were able to inhibit gonadotropin-induced in vitro proliferation of ovarian cancer cell lines by co-incubation with a GnRH-agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Oral contraceptives and breast cancer. A review with some comments on mathematical models

The relationship between oral contraceptive use and breast cancer is discussed on the basis of information given in review articles, meta-analyses and editorials emphasizing methodological problems related to bias and confounding. Over the last few years a shift in opinion has taken place. Most reviewers now consider that long-term use of oral contraceptives is associated with an increased risk of premenopausal breast cancer and no effect among postmenopausal breast cancer. This result is compatible with an additive effect (in rate measure scale) of oral contraceptive use on breast cancer risk.

Oral contraceptives and breast disease

Epidemiologic data support the hypothesis that the types of OCs used before the mid-1970s protected against most forms of benign breast disease. It is unclear whether current low-dose progestogen OCs will confer the same protection. Further studies are necessary to clarify this. For breast cancer, the relationship is more complex. It is possible that prolonged use of high-dose OCs exert a small increased risk for breast cancer development in women before age 45. Furthermore, prolonged use before a first term pregnancy may result in a small increase in risk for breast cancer before age 45. Studies evaluating the effect of current low-dose OCs are necessary to elucidate what, if any, effect they may have on breast cancer development. Furthermore, as our population ages, studies will be able to determine what effect, if any, may be present in women over age 60, those women with the highest underlying risk of breast cancer. And finally, more research of basic breast tissue physiology and the effect of endogenous and exogenous hormones on this complex organ is needed.

Biology of female sex hormone action in relation to contraceptive agents and neoplasia

This article will present an overview of estrogen and progestin action at a cellular level, with emphasis on points that are relevant to neoplasia. In breast, endometrium and ovary, these two classes of hormone are clearly implicated in carcinogenesis, but their involvement with cancers of the liver, cervix and other tissues is more problematic. In the latter situations, I will highlight the major points to be considered if the hormones are involved without wishing to judge whether there actually is a causal involvement.

Oral contraceptives and breast cancer

Among women in general the risk of breast cancer through 59 years of age does not appear to be affected appreciably by the use of oral contraceptives. Nonetheless, concern continues to be expressed about the effects of early age at first use, long-term duration of use, formulation, and a variety of other factors thought to influence breast cancer risk in the presence of oral contraception. A number of recent studies restricted to young women suggest that long-term use may increase the risk of disease occurring very early, but the present lack of consistent findings in well-conducted epidemiologic studies prevents any certain conclusion with regard to cause-and-effect. However, if an increased risk were indeed present, the most plausible interpretation is that long-term oral contraception promotes earlier clinical manifestation of breast cancer in some women while having no net impact on their lifetime risk of the disease.

Oral contraceptives and risk of breast cancer

A national population-based case-control study was conducted in New Zealand to assess the effects of hormonal contraception on breast-cancer risk. A total of 891 women aged 25 to 54 with a first diagnosis of breast cancer, and 1864 control subjects, randomly selected from the electoral rolls, were interviewed. The relative risk of breast cancer for women who had ever used oral contraceptives was 1.0 (95% confidence interval 0.82-1.3). There was no increase in risk with duration of use, even among women who had continued to use oral contraceptives for 14 or more years (relative risk = 1.1, 95% confidence interval 0.78-1.7). The risk of breast cancer was not increased by use of oral contraceptives for long periods before the first pregnancy or by starting use at a young age. Parity, age at menarche, family history of breast cancer, or history of benign breast disease did not modify the effect of oral contraceptives on breast-cancer risk. Relative risk estimates were slightly, although not significantly, increased during the first few years after starting oral contraception and in women under 35 years of age at diagnosis.