Oral contraceptives and cancer. A review of the evidence

Combined Oral Contraceptive Use and the Risk of Cervical Cancer: Literature Review

Cervical cancer (CC) is caused by persistent infection of human papillomavirus of high oncogenic risk (hr-HPV); however, several cofactors are important in its carcinogenesis, such as smoking, multiparity, and prolonged use of oral hormonal contraceptives (COCs). Worldwide, 16% of women use COCs, whereas in Brazil this rate is of ∼ 30%. The safety and adverse effects of COCs are widely discussed in the literature, including the increase in carcinogenic risk. Due to the existence of several drugs, combinations, and dosages of COCs, it is hard to have uniform information in epidemiological studies. Our objective was to perform a narrative review on the role of COCs use in the carcinogenesis of cervical cancer. Several populational studies have suggested an increase in the incidence of cervical cancer for those who have used COCs for > 5 years, but other available studies reach controversial and contradictory results regarding the action of COCs in the development of CC.

Oral contraceptives and colorectal cancer risk - A meta-analysis and systematic review

There is limited understanding of the potential relationship between the risk of colorectal cancer and oral contraceptive use among women of different ages. Further investigation on the issue helps develop an informed choice of contraception. Data for this meta-analysis were derived from case-control and cohort studies of colorectal cancer and oral contraceptive use conducted between June 2000 and May 2022. The studies had a very high heterogeneity, as shown by an I² of 99%, and a confidence interval of 95% was considered significant. Other results from the meta-analysis were as follows; Heterogeneity: Chi² = 585.13, df = 6 (P < 0.00001). A test of the overall effect of ever use versus never use of oral contraceptives was Z = 21.85 (P < 0.00001). All the studies had a pooled risk ratio (RR) of 0.53. The use of oral contraceptives is associated with reduced risk of developing colorectal cancer. There is a need for further research into the biological mechanisms underlying these relationships, which may lead to insights into potential preventive interventions for colorectal carcinogenesis in women. The keywords used to locate studies included in this meta-analysis include Keywords targeting oral contraceptives included oral contraceptive pills, and birth control pills. Search keywords targeting colorectal carcinogenesis included neoplasms, tumors, or colon and rectal cancer.

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Oral contraceptive use in woman does affect the risk of developing colorectal cancer.

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Colorectal cancer has many identifiable and nonidentifiable risk factors.

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OCP usage in women of various age groups shown a lower risk of colorectal cancer development than those who never used OCPs.

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Regarding the population at risk for colorectal cancer due to a variety of reasons, many studies have deemed OCP usage safe.

Endocrine disruption of oestrogen action and female reproductive tract cancers

Endocrine disrupting chemicals (EDC) are ubiquitous and persistent compounds that have the capacity to interfere with normal endocrine homoeostasis. The female reproductive tract is exquisitely sensitive to the action of sex steroids, and oestrogens play a key role in normal reproductive function. Malignancies of the female reproductive tract are the fourth most common cancer in women, with endometrial cancer accounting for most cases. Established risk factors for development of endometrial cancer include high BMI and exposure to oestrogens or synthetic compounds such as tamoxifen. Studies on cell and animal models have provided evidence that many EDC can bind oestrogen receptors and highlighted early life exposure as a window of risk for adverse lifelong effects on the reproductive system. The most robust evidence for a link between early life exposure to EDC and adverse reproductive health has come from studies on women who were exposed in utero to diethylstilbestrol. Demonstration that EDC can alter expression of members of the HOX gene cluster highlights one pathway that might be vulnerable to their actions. In summary, evidence for a direct link between EDC exposure and cancers of the reproductive system is currently incomplete. It will be challenging to attribute causality to any single EDC when exposure and development of malignancy may be separated by many years and influenced by lifestyle factors such as diet (a source of phytoestrogens) and adiposity. This review considers some of the evidence collected to date.

Ovarian cancer risk in postmenopausal women using estradiol-progestin therapy - a nationwide study

OBJECTIVE

While previous data link the use of postmenopausal hormone therapy to an increased risk for ovarian cancer, little is known about the impact of various progestins, modes or routes of administration of hormone therapy for this risk. In this nationwide study, we compared relations between different estradiol-progestin (EPT) formulations and epithelial ovarian cancer risk.

METHODS

All Finnish women over 50 years using EPT for at least 6 months (224 015 women with 602 ovarian cancers) during 1994-2006 were identified from the reimbursement register. The incidence of ovarian cancer in EPT users was compared to that in the age-matched background population by means of observed to expected ratio (standardized incidence ratio, SIR).

RESULTS

Ovarian cancer risk was not elevated for EPT use of < 5 years but it was elevated for EPT use of ≥5 years (SIR 1.21, 95% confidence interval (CI) 1.06-1.37). Medroxyprogesterone acetate and norethisterone acetate as components of EPT were associated with similar risks for use for ≥ 5 years (SIR 1.26, 95% CI 0.94-1.64 and SIR 1.42, 95% CI 1.11-1.77, respectively). The risk did not differ between sequential or continuous EPT regimens or between oral or transdermal EPT formulations. The risk elevation for EPT use for ≥ 5 years was seen only for serous (SIR 1.56; 95% CI 1.33-1.80) and mixed cancers (SIR 1.54; 95% CI 1.22-1.91), whereas the risk for mucinous cancer was decreased (SIR 0.47; 95% CI 0.22-0.86).

CONCLUSION

The elevated risk of non-mucinous ovarian cancer in users of EPT ≥ 5 years does not depend on progestin type, mode or route of administration of EPT.

Histology-specific long-term trends in the incidence of ovarian cancer and borderline tumor in Japanese females: a population-based study from 1983 to 2007 in Niigata

AIM

The histology-specific long-term trends in the incidence of ovarian cancer and borderline tumors in Japanese women were examined, based on data from the population-based cancer registry in Niigata, Japan.

MATERIAL AND METHODS

Data were obtained from the Niigata Gynecological Cancer Registry, which covered the entire female population in Niigata prefecture, Japan, during the period from 1983 to 2007.

RESULTS

A total of 3134 females with epithelial ovarian cancer, including borderline tumor cases, were diagnosed between 1983 and 2007. The age-standardized rates (ASRs) of both ovarian cancer and borderline tumors have steadily increased, with significant changes in ovarian cancer in all age groups, and borderline ovarian tumors in subjects aged <50. The ASRs of endometrioid adenocarcinoma showed a steady increasing trend, and those of clear cell and mucinous adenocarcinomas showed significant increasing trends in the total population. The ASRs of clear cell, mucinous, and endometrioid adenocarcinomas in the 50+ age group were significantly increased, especially the incidence of clear cell adenocarcinoma, which strikingly increased by approximately threefold from 1.2 (1983-1989) to 3.5 (2000-2007) per 100,000 females.

CONCLUSION

This prefecture-wide study showed the practical trends in ovarian cancer and borderline tumors in Japanese females. The incidence of ovarian cancer has steadily increased, with significant increases in the incidence of clear cell and mucinous adenocarcinomas in the total population during the past two decades. Because of the poor response rate of these histological subtypes to platinum-based regimens, novel treatment approaches should be adopted to improve the prognostic outcome in patients with ovarian cancer in Japan.

Hepatocellular carcinoma: management of an increasingly common problem

Hepatocellular carcinoma (HCC) is a common cancer that typically occurs in the setting of cirrhosis and chronic hepatitis virus infections. Hepatitis B and C account for approximately 80% of cases worldwide. HCC is currently the fifth most common malignancy in men and the eighth in women worldwide; its incidence is increasing dramatically in many parts of the world. Recognition of those at risk and early diagnosis by surveillance with imaging, with or without serologic testing, are extremely important. Many highly effective and even curative therapies are now available and include resection, liver transplantation, and local ablation. Appropriate application of these interventions offers hope of prolonged survival to many patients with this otherwise lethal complication of liver disease.

Systematic literature reviews and meta-analyses: part 6 of a series on evaluation of scientific publications

BACKGROUND

Because of the rising number of scientific publications, it is important to have a means of jointly summarizing and assessing different studies on a single topic. Systematic literature reviews, meta-analyses of published data, and meta-analyses of individual data (pooled reanalyses) are now being published with increasing frequency. We here describe the essential features of these methods and discuss their strengths and weaknesses.

METHODS

This article is based on a selective literature search. The different types of review and meta-analysis are described, the methods used in each are outlined so that they can be evaluated, and a checklist is given for the assessment of reviews and meta-analyses of scientific articles.

RESULTS

Systematic literature reviews provide an overview of the state of research on a given topic and enable an assessment of the quality of individual studies. They also allow the results of different studies to be evaluated together when these are inconsistent. Meta-analyses additionally allow calculation of pooled estimates of an effect. The different types of review and meta-analysis are discussed with examples from the literature on one particular topic.

CONCLUSIONS

Systematic literature reviews and meta-analyses enable the research findings and treatment effects obtained in different individual studies to be summed up and evaluated.

Hormonal treatments and epithelial ovarian cancer risk

Exogenous sex hormones are widely used by women either for pregnancy prevention, as part of infertility treatment, or for treatment of menopausal symptoms. The role of these hormones in the development of ovarian cancer has been vastly explored. The protective effect of combined oral contraceptive pill is confirmed in multiple studies, but it is not clear whether this protection also covers women with a genetic predisposition to ovarian cancer. There is no conclusive evidence of infertility treatments increasing ovarian cancer risk, but infertility as such is a risk factor. Currently available data suggest that long-term users of hormone replacement therapy may have a slightly increased risk for ovarian cancer compared to women who have never used estrogen. The risk might particularly involve the endometrioid type of ovarian cancer. Most data on ovarian cancer and estrogen comes from epidemiological studies, since the normally high concentrations of estrogens in ovarian tissue and follicular fluid make direct biologic studies on the effects of exogenous estrogens on the ovarian cell difficult. This review discusses the risk of ovarian cancer associated with the use of sex steroid hormones, with special emphasis on the possible risk associated with estrogens.

Epidemiology of hepatocellular carcinoma

Year 2000 estimates of the incidence of cancer indicate that primary liver cancer remains the fifth most common malignancy in men and the eighth in women. The number of new cases has been predicted as 564,000, corresponding to 398,000 in men and 166,000 in women. The geographic areas at highest risk are located in Eastern Asia, Middle Africa, and some countries of Western Africa. Changes in incidence among migrant populations underline the predominant role of environmental factors in the etiology of primary liver cancer. In high-risk countries, the early cases of primary liver cancer occur already at ages 20 and above, underlying the impact of viral exposures early in life. In countries at low risk, primary liver cancer is rare before the 50s, translating the impact of late exposures with moderate risks and long latency intervals. Sex ratios are typically between 2 and 4. The incidence of primary liver cancer is increasing in several developed countries including the United States, and the increase will likely continue for several decades. The trend has a dominant cohort effect related to exposures to hepatitis B and C viruses. The variability of primary liver cancer incidence is largely explained by the distribution and the natural history of the hepatitis B and C viruses. The attributable risk estimates for the combined effects of these infections account for well over 80% of liver cancer cases worldwide. Primary liver cancer is the first human cancer largely amenable to prevention using hepatitis B virus vaccines and screening of blood and blood products for hepatitis B and C viruses.

Primary liver cancer: worldwide incidence and trends

Estimates from the year 2000 indicate that liver cancer remains the fifth most common malignancy in men and the eighth in women worldwide. The number of new cases is estimated to be 564,000 per year, including 398,000 in men and 166,000 in women. In high-risk countries, liver cancer can arise before the age of 20 years, whereas, in countries at low risk, liver cancer is rare before the age of 50 years. Rates of liver cancer in men are typically 2 to 4 times higher than in women. The incidence of primary liver cancer is increasing in several developed countries, including the United States, and the increase will likely continue for some decades. The trend is a result of a cohort effect related to infection with hepatitis B and C viruses, the incidence of which peaked in the 1950s to 1980s. In selected areas of some developing countries, the incidence of primary liver cancer has decreased, possibly as a result of the introduction of hepatitis B virus vaccine. The geographic variability in incidence of primary liver cancer is largely explained by the distribution and the natural history of the hepatitis B and C viruses. The attributable risk estimates for the combined effects of these infections account for well over 80% of liver cancer cases worldwide. Primary liver cancer is the first human cancer largely amenable to prevention using hepatitis B virus vaccines and screening of blood and blood products for hepatitis B and C viruses.

Oral contraceptives and reproductive system cancer

Extensive research during the last 20 years has shown that oral contraceptives are safe. Several recent epidemiological studies have confirmed that combined oral contraceptives (COCs) provide substantial protection against endometrial and ovarian cancer, and this protection is long-lasting and may persist for 15 or more years after termination of OC use. In many studies COCs have been associated with an increased risk of cervical abnormalities and cervical cancer, but there might be alternative explanations for these epidemiological associations (COC users can start having sexual intercourse at an earlier age, they have more sexual partners, and they rarely use barrier methods of contraception), so OCs act as a promoter for HPV-induced carcinogenesis. Finally, women who are currently using COCs or have used them in the past 10 years are at a slightly increased risk of having breast cancer during the next 10 years, although the additional cancers diagnosed tend to be localized to the breast and they are less advanced clinically than the cancers diagnosed in those who have never used COCs.

Prevalence and persistence of human papillomavirus in postmenopausal age women

Little is known about the prevalence and persistence of human papillomavirus (HPV) in older women, or about the association between hormone replacement therapy (HRT) use and HPV detection. Like oral contraceptives, HRT hormones may upregulate viral expression and subsequent risk of genital cancer. Postmenopausal women seeking routine gynecologic care were evaluated for HPV infection, testing cervical/vaginal cytology by PCR/DNA sequencing. The prevalence of HPV was 14%; 6% had oncogenic types and 5.8% had persistent infection. Although risk of HPV detection was non-significantly elevated after adjustment for age and HPV-related risk factors among current (adjusted odds ratio (OR)=2.3) and past (adjusted OR=3.2) hormone users compared to never users, past users had a significantly higher risk using combination HRT regimens with increasing duration (adjusted OR=1.8 per year; 95% confidence interval (CI)=1.1-3.1). These findings suggest that a significant percentage of older women are infected with HPV. This may put them at increased risk of genital cancers with longer use of HRTs. Additional studies are needed.

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.

Oral contraceptives and cancer: an update

Most up-to-date information on oral contraceptives (OCs) and breast cancer risk comes from a collaborative re-analysis of individual data on 53297 cases and 100239 controls. It is now established that there is a moderately increased breast cancer risk among current OC users, which tends to level off in the few years after stopping use. With regard to cervical cancer, OC use has been found to be associated with increased risk in human papilloma virus-positive women. With reference to the well known protective effects of OCs against endometrial carcinogenesis, additional information has suggested a consistent protection across types of OCs used. Further data on ovarian cancer confirm that the protection of OCs is long lasting, and may well be observed 15 to 20 years after stopping use. Several studies have suggested an inverse relationship between use of OCs and risk of colorectal cancer, and in a meta-analysis of published data the pooled relative risk of colorectal cancer for DC ever-use was 0.82 (95% confidence interval 0.74 to 0.97). There was no association with duration of use. The increased risk for hepatocellular carcinoma in the absence of hepatitis B viruses is the only established evidence of a direct association between OC use and cancer risk, which led an International Agency for Research on Cancer Working Group to classify OCs as carcinogenic to humans in 1998.

Triphasic oral contraceptives: review and comparison of various regimens

OBJECTIVE

To review and compare the risk-benefit profile of triphasic oral contraceptives with that of low-dose monophasic oral contraceptives.

DESIGN

Literature on currently marketed triphasics and monophasics.

PATIENT(S)

Healthy women of reproductive age.

MAIN OUTCOME MEASURE(S)

Comparison of the rationale for development, composition, mechanism, efficacy, menstrual cycle control, side effects, health benefits, and risk-benefit profile.

RESULT(S)

All triphasics contain ethinyl estradiol (0.025-0.040 mg/d) and one of several progestins in doses (0.05-1.0 mg/d) related to their relative potencies, which are substantially lower overall (total dose) than those in monophasics. The triphasics are highly efficacious. In general, menstrual cycle control and side effects are similar in both types, but triphasics containing the newer progestins (desogestrel, gestodene, and norgestimate) have better cycle control and a reduced incidence of androgenic side effects compared with those with norethindrone or levonorgestrel. Both triphasics and monophasics have minimal effects on carbohydrate and lipid metabolism and hemostasis parameters, and therefore comparable low risks of coronary heart disease. The health benefits of triphasics and monophasics are similar and include decreased incidence of unwanted and ectopic pregnancies, ovarian cysts, endometrial and ovarian cancers, benign breast disease, and acute pelvic inflammatory disease; less menstrual blood loss and iron deficiency anemia; and lower frequency of irregular bleeding and menorrhagia.

CONCLUSION(S)

The risk-benefit profiles of both triphasics and monophasics are favorable and similar.

The effect of the duration of progestin use on the occurrence of endometrial cancer in postmenopausal women

OBJECTIVE

Women who have ever used estrogen replacement therapy (ERT), even at a low dose, have an increased incidence of endometrial cancer. The addition of a progestin to ERT reduces the incidence of endometrial cancer. The duration of progestin administration is more important than the dose.

DESIGN

A MEDLINE review of the literature was performed using the search terms endometrial cancer, epidemiology, and hormone replacement therapy (HRT).

RESULTS

Women who have ever used ERT have an increased incidence of endometrial cancer. The use of HRT for more than 5 years, with a progestin use of <10 days per cycle, has a relative risk = 1.8. Continuous combined HRT, or sequential or cyclic HRT with >10 days of progestin per cycle, appears to decrease the incidence of endometrial cancer to that found in nonusers of HRT.

CONCLUSIONS

The use of HRT in postmenopausal women with a uterus reduces the incidence of endometrial cancer. The duration of progestin administration should be 14 days or more per cycle based on recent epidemiologic data.

Cancer-related risk indicators and preventive screening behaviors among lesbians and bisexual women

OBJECTIVES

This study examined whether lesbians are at increased risk for certain cancers as a result of an accumulation of behavioral risk factors and difficulties in accessing health care.

METHODS

Prevalence estimates of behavioral risk factors (nulliparity, obesity, smoking, and alcohol use), cancer screening behaviors, and self-reported breast cancer histories derived from 7 independently conducted surveys of lesbians/bisexual women (n = 11,876) were compared with national estimates for women.

RESULTS

In comparison with adjusted estimates for the US female population, lesbians/bisexual women exhibited greater prevalence rates of obesity, alcohol use, and tobacco use and lower rates of parity and birth control pill use. These women were also less likely to have health insurance coverage or to have had a recent pelvic examination or mammogram. Self-reported histories of breast cancer, however, did not differ from adjusted US female population estimates.

CONCLUSIONS

Lesbians and bisexual women differ from heterosexual women in patterns of health risk. These women would be expected to be at especially greater risk for chronic diseases linked to smoking and obesity.

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.

The pill and cancer

The relation between oral contraceptives (OC) and cancer risk has been investigated extensively, mainly with reference to breast, female genital tract, liver cancer and cutaneous malignant melanoma, and will be summarized below. There is also some suggestion that OC use is related to other neoplasms, including a reduced risk of colorectal cancer among OC users, but the issue is still controversial and too preliminary to provide indications for informed contraception choice.

Endometrial histology during use of a low-dose estrogen-desogestrel oral contraceptive with a reduced hormone-free interval

The object of the study was to determine the effect of a new low-dose ethinyl estradiol-desogestrel oral contraceptive on endometrial histology. The oral contraceptive regimen contained fixed doses of ethinyl estradiol (20 micrograms) and desogestrel (150 micrograms) for days 1-21, placebo on days 22 and 23, and ethinyl estradiol alone (10 micrograms) on days 24-28. Endometrial histology was assessed in tissue samples obtained during treatment cycles 13 and 14. All endometrial samples were sent to a central laboratory for processing and evaluation. No endometrial hyperplasia or metaplasia was found in the endometrial biopsy specimens obtained during cycles 13 and 14 in a subset of 12 women participating in a multicenter efficacy and safety study. These results suggest that this oral contraceptive regimen, which includes 5 days of unopposed ethinyl estradiol, is not associated with endometrial hyperplasia or metaplasia. The endometrial histologic findings observed in this study were similar to those observed during the use of 21-day combination oral contraceptive regimens.

Epidemiology and biology of cervical cancer

Worldwide, cancer of the cervix is the second leading cause of cancer death in women: each year, an estimated 500,000 cases are newly diagnosed. Among populations, there are large differences in incidence rates of invasive cervical cancer: these reflect the influence of environmental factors, screening Papanicolaou (Pap) tests, and treatment of pre-invasive lesions. The high-risk human papillomavirus (HPV) subtypes 16, 18, 31, 33, and 51 have been recovered from more than 95% of cervical cancers. We have made great strides in understanding the molecular mechanism of oncogenesis of this virus, focusing on the action of the E6 and E7 viral oncoproteins. These oncoproteins function by inactivating cell cycle regulators p53 and retinoblastoma (Rb), thus providing the initial event in progression to malignancy. Cervical cancers develop from precursor lesions, which are termed squamous intraepithelial lesions (SIL) and are graded as high or low, depending on the degree of disruption of epithelial differentiation. Viral production occurs in low-grade lesions and is restricted to basal cells. In carcinomas, viral DNA is found integrated into the host genome, but no viral production is seen. The well-defined pre-invasive stages, as well as the viral factors involved at the molecular level, make cervical carcinoma a good model for investigating immune therapeutic alternatives or adjuvants to standard treatments.

A pilot efficacy study with a single-rod contraceptive implant (Implanon) in 200 Indonesian women treated for < or = 4 years

In this 4-year open-label, noncomparative, single-center pilot efficacy study, the contraceptive efficacy, safety, bleeding pattern and acceptability of Implanon was studied in 200 sexually active women of proven fertility in Indonesia. All subjects received the single-rod subdermal implant Implanon, which contains 68 mg etonogestrel (3-keto-desogestrel), with an initial release rate of 67 micrograms etonogestrel/day. Contraceptive efficacy was analyzed by calculation of the pregnancy rate, bleeding patterns were determined by the 90-day reference period method, and acceptability by the discontinuation rate. No in-treatment pregnancies were reported during 658.4 women-years of exposure, resulting in a Pearl Index of 0.0 (95% CI 0.0-0.6). The overall bleeding pattern was acceptable, with no discontinuations because of irregular bleeding. Incidence of irregular bleeding was highest during the first two reference periods and decreased thereafter. Amenorrhea was experienced by 7%-12% of subjects during years 1 and 2, by 5%-7% during year 3, and by 2%-5% during year 4, with one discontinuation because of amenorrhea. No clinically significant changes were reported for systolic and diastolic blood pressure, body mass index, and hemoglobin level. Three adverse experiences were related to treatment and resulted in discontinuation (two headaches and one dyspnea). One difficult implant removal was reported. In conclusion, this pilot efficacy study indicates that Implanon provides excellent contraceptive reliability and an acceptable bleeding pattern. Overall safety and acceptability are good, as suggested by the low incidence of adverse experiences and the low discontinuation rate.

Hormonal treatment of endometrial cancer

This article summarizes the endocrine background of women with endometrial cancer at both peripheral and tissue levels, and the current status of clinical trials of hormonal, cytotoxic, and combination regimens. Because significant advances in systemic therapy are required to improve the prognosis of endometrial cancer, recommendations for future clinical investigations will be based on these recent biologic observations.

Borderline ovarian tumours in Vaud, Switzerland: incidence, survival and second neoplasms

Between 1976 and 1996, 176 borderline ovarian tumours were registered in the Cancer Registry of the Swiss canton of Vaud, corresponding to an age-adjusted incidence (world standard) of 2.7 in 100,000. Incidence rose from 1.7 per 100,000 during 1976-81 to 2.7 per 100,000 during 1987-91, and then levelled off; 58% of cases were serous and 41% mucinous. Relative survival was 94% at 10 years; 18 second neoplasms were observed, compared with 10.3 expected, and there was a significant excess of invasive ovarian cancers (four observed, including three synchronous, compared with 0.4 expected).

Oral contraceptive use and benign gynecologic conditions. A review

The following review considers the main epidemiologic data on oral contraceptives (OC) and the risk of major benign gynecologic diseases. Earlier studies investigating the relationship between OC use and functional ovarian cysts indicated that the use of high-dose combination OC have a protective effect, whereas low-dose monophasic or multiphasic pills have little or no effect. With regard to seromucinous cysts, the scanty data available are consistent with the notion of some protection of OC in current but not in former users, although possible effects of diagnostic and selection bias should be considered. Published data on the relationship between fibroids and OC appear too scattered to allow a precise quantification of risk. In any case, any relationship is moderate and, hence, of limited clinical and public health relevance. The data on OC and benign gynecologic conditions are reassuring in their absence of any consistent excess risk.