4

Information for Users of the Pill and Health Care Providers

Oral contraceptives are widely used and have been the object of more studies and data gathering than any other pharmaceutical preparation. Nonetheless, widespread consumer confusion prevails. A 1985 poll on consumer perception conducted for the American College of Obstetricians and Gynecologists revealed that (1) 75 percent of women believed that the pill carried substantial health risks, (2) 33 percent believed that the pill caused cancer, and (3) 66 percent believed that taking the pill was more dangerous than bearing a child. In light of these findings, the public must be kept better informed, and health care providers must keep themselves informed of the current status of the health benefit/risk ratio relative to the use of oral contraceptives.

BENEFITS AND RISKS OF ORAL CONTRACEPTIVES

Benefits

The pill is the most effective, reversible contraceptive in widespread use today. In the United States, it is a major factor in preventing unintended pregnancy and induced abortion.

Aside from their extraordinary effectiveness as contraceptives, oral contraceptives have been shown to have numerous noncontraceptive benefits (Table 4-1). The pill usually regulates menstrual cycles and reduces menstrual flow, thus preventing iron-deficiency anemia and



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Oral Contraceptives & Breast Cancer 4 Information for Users of the Pill and Health Care Providers Oral contraceptives are widely used and have been the object of more studies and data gathering than any other pharmaceutical preparation. Nonetheless, widespread consumer confusion prevails. A 1985 poll on consumer perception conducted for the American College of Obstetricians and Gynecologists revealed that (1) 75 percent of women believed that the pill carried substantial health risks, (2) 33 percent believed that the pill caused cancer, and (3) 66 percent believed that taking the pill was more dangerous than bearing a child. In light of these findings, the public must be kept better informed, and health care providers must keep themselves informed of the current status of the health benefit/risk ratio relative to the use of oral contraceptives. BENEFITS AND RISKS OF ORAL CONTRACEPTIVES Benefits The pill is the most effective, reversible contraceptive in widespread use today. In the United States, it is a major factor in preventing unintended pregnancy and induced abortion. Aside from their extraordinary effectiveness as contraceptives, oral contraceptives have been shown to have numerous noncontraceptive benefits (Table 4-1). The pill usually regulates menstrual cycles and reduces menstrual flow, thus preventing iron-deficiency anemia and

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Oral Contraceptives & Breast Cancer TABLE 4-1 Well-established Major Protective Effects of Oral Contraceptives (OC) by Problem or Condition, United Kingdom or United States   Relative Risk     Problem or Condition Protected Against Current Use Past Use Influenced by Duration of Use Influenced by OC Formulation Menstrual problems a 0.75 1.0 No Yes—protection decreases with “low-dose” pills Iron-deficiency anemia a 0.75 1.0 No Unknown Benign breast cysts a 0.5 1.0 Yes—protection increases as duration increases Yes—protection increases as progestin increases Pelvic inflammatory disease a 0.5 1.0 Unknown Unknown Functional ovarian cysts a 0.25 1.0 No Probably not Epithelial ovarian cancer b 0.5 0.5 Yes—protection increases as duration increases Probably not Endometrial cancer b 0.5 0.5 Yes—protection increases as duration increases Probably not a Based on hospital admissions data. b Based on incidence data. SOURCE: Adapted from M. P. Vessey, "The Jephcott Lecture, 1989: AnOverview of the Benefits and Risks of Combined Oral Contraceptives,"in Oral Contraceptives and Breast Cancer, R. D. Mann, ed. (Park Ridge, N.J.: The Parthenon Publishing Group,1990). reducing hospital admissions for problems related to menorrhagia. Evidence also indicates that the risk of pelvic inflammation decreases in women taking the pill. (Some recent work suggests, however, that the pill is associated with an increased risk of chlamydial infection, although a clear association has not been established in a prospective study.) Use of the pill is associated with decreased risk of ovarian tumors, both benign and malignant; in addition, the risk of endometrial carcinoma begins to decline after one year of oral contraceptive use. Protection against ovarian and endometrial malignancy is greatest in nulliparous women. The risk of ectopic pregnancy and its adverse effects on reproductive health are also decreased in pill users (because most oral contraceptives prevent ovulation, which, of course, precludes pregnancy, ectopic or otherwise).

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Oral Contraceptives & Breast Cancer Risks In the history of unraveling the side effects of the pill, the first described complication of oral contraceptives was related to cardiovascular problems (Table 4-2). The relative risk of venous thrombosis for current users is an estimated 5 times that for nonusers, with a low absolute risk. It seems that venous thrombosis and pulmonary embolism are related mostly to the pill's estrogenic component, whereas other cardiovascular complications relate primarily to the progestin component. Myocardial infarction is rare in young women, and no deaths have been reported in users of the pill who are under 25 years of age, even among smokers. Episodes of acute hypertension are almost nonexistent in users of pill formulations that contain less than 50 μg of estrogen. Both thrombotic and hemorrhagic stroke have been described and can be identified in 5 to 10 percent of all deaths in women who were using oral contraceptives at the time of their death. Recent studies have shown that, with the exception of subarachnoid hemorrhage, there is no increase in risk of stroke among nonsmokers who use oral contraceptives. Careful patient screening and physician sensitivity to premonitory symptoms, especially headaches, should decrease the risk. There is no substantially increased risk of stroke among former users of steroid contraception. An association has been observed between oral contraceptives and the occurrence of rare hepatocellular adenomas. These tumors are benign but can be associated with pill use (Table 4-2). For hepatocellular carcinoma, which is also rare (i.e., approximately 1 case per 100,000 women in the United States), pill users face a risk three times that of nonusers. CURRENT CONTROVERSY It is estimated that one American woman in nine develops breast cancer sometime in her life, thus reducing by 25 percent her chances of surviving the next five years. The major correlate of risk is a woman 's age. Breast cancer is rarely evident in the mid-teens. By age 30-34, the annual occurrence is 30 cases per 100,000 women; by age 70-74, the rate has increased to 424 cases per 100,000 women (1986 data; see

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Oral Contraceptives & Breast Cancer TABLE 4-2 Well-established Major Adverse Effects of Oral Contraceptives (OC), United Kingdom or United States   Relative Risk     Adverse Effect a Current Use Past Use Influenced by Duration of Use Influenced by OC Formulation Acute myocardial infarction b 2 1 Probably not Probably yes—risk increases as estrogen and progestin increase Thrombotic stroke b 5 1 Probably not Unknown Hemorrhagic stroke b 1.5 1.5 Probably not Unknown Venous thromboembolism b 5 1 No Probably yes—risk increases as estrogen increases Hepatocellular adenoma c 50 Yes—risk increases as duration increases Yes—risk increases, with “high-dose” pills Hepatocellular carcinoma d 3 Yes—risk increases as duration increases Unknown a Data are not included on hypertension because the adverse consequences of this condition are expressed in terms of myocardial infarction or stroke. b Based on data for hospital admissions or deaths. c Based on incidence data. d Based on incidence and mortality data. SOURCE: Adapted from M. P. Vessey, "The Jephcott Lecture, 1989: AnOverview of the Benefits and Risks of Combined Oral Contraceptives,"in Oral Contraceptives and Breast Cancer, R. D. Mann, ed. (Park Ridge, N.J.: The Parthenon Publishing Group,1990). Table 1-7). After age and nationality, the major risk factors for breast cancer are (1) early age at menarche, (2) late age at menopause, (3) nulliparity, (4) late age at first full-term pregnancy, (5) breast cancer in first-degree relatives, and (6) elevated postmenopausal weight. Despite the effectiveness of the pill as a contraceptive agent, its numerous noncontraceptive benefits, and evidence that the cumulative risk of breast cancer through at least age 45 appears to have no relationship to pill use, significant uncertainty and concern remain. Several recent epidemiological studies restricted to women under the age of 45 have raised the possibility of an adverse effect from long-term oral contraceptive use before a first full-term pregnancy. Given

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Oral Contraceptives & Breast Cancer the fact that the majority of pill users in this country are now younger women who have not yet had such a pregnancy and who take the pill for extended periods, this concern and the recognition that further studies are needed seem most appropriate. At present, it is unknown if, in fact, risk of breast cancer increases in younger pill users who have used the pill for a long time—whether or not they have had their first full-term pregnancy. Epidemiological research studies must be structured to answer this question. If such studies do show increased risk, several questions must be answered: (1) What is the magnitude of the risk? (2) How long does it persist? and (3) Given the overall benefit/risk ratio of the pill, is its continued use warranted? PRESCRIBING PROBLEMS Health professionals must provide concise, accurate counsel to their patients based on a clear, current understanding of the balance of benefits and risks of pill use and the user's health and sociocultural status. The absolute contraindications to pill use, as they appear in the patient package insert, are: undiagnosed abnormal genital bleeding; presence or history of breast or liver malignancy; thromboembolic disorders; cerebrovascular disease; myocardial infarction; known or suspected estrogen-dependent neoplasia; and known or suspected pregnancy. Additionally, a number of factors place a patient at a potentially higher risk for complications with the use of oral contraceptives. A list of these factors appears in the package insert, as follows: age over 40; heavy smoking over age 35; family history of premature death from cardiovascular disease; hypertension; abnormal metabolic conditions; gestational diabetes; hyperlipidemia; severe migraine; and chronic liver disease. In 1989, an advisory committee of the Food and Drug Administration recommended removal of any upper age limit. It is important to note that practitioners are obliged to provide women with information about the current state of ambiguity regarding the relationship between oral contraceptives and breast cancer. Some women will be distressed by this lack of a clear picture and will find it difficult to incorporate this uncertainty into their decision-making process. They should be encouraged, however, to look at the total picture—especially the known benefits and risks of oral contraceptives, as well as the known benefits and risks of other birth control methods, and the risks of unintended pregnancy—in making their choices about contraception. For many women, the

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Oral Contraceptives & Breast Cancer convenience and dependability of the pill will continue to outweigh worries about a possible link to breast cancer. For others, this possible link will provide motivation to use another method. Adequate information and supportive counseling will help each woman sort through her own, unique situation. Although the possibility exists that younger pill users may have increased risk of breast cancer prior to first full-term birth, based on the current state of knowledge as to the benefit/risk ratio of pill use, the committee recommends no fundamental change in prescribing practice for oral contraceptives at this time.