The correct answer is D. Numerous studies have demonstrated that use of the oral contraceptive pill significantly decreases a woman's likelihood of developing endometrial cancer. Overall, use of the oral contraceptive pill appears to decrease the risk by approximately 50%, with greatest effects in those using the pill for more than 3 years. One theory to explain the decreased endometrial cancer risk in oral contraceptive users is that the oral contraceptive pill provides almost continuous exposure of the endometrium to progestins. The major factor in the development of endometrial cancer is estrogen exposure, whether endogenously (e.g., because of obesity or chronic anovulation) or exogenously (e.g., from unopposed estrogen replacement therapy). By providing almost daily exposure to progestins, the oral contraceptive pill works to counteract the effects of estrogens. Over time, women on the OCP develop thinner endometrial linings and have a lower risk for developing endometrial cancer.
There is no clear relationship between bone cancer (choice A) and OCP use.
The relationship between breast cancer (choice B) and oral contraceptives remains unclear at this time. There is some evidence that current users and those who have recently stopped may be at some increased risk for breast cancer. There is also evidence, however, that when breast cancer is diagnosed in an oral contraceptive user, it tends to be more localized than in a nonuser.
The relationship between cervical cancer (choice C) and the OCP also remains unclear at this time. Overall the results have been inconclusive. All sexually active patients should have regular screening for cervical dysplasia with a Pap smear starting at age 18 years or with the onset of sexual intercourse. Cervical cancer is primarily related to human papilloma virus infection and there is an increased risk for cervical cancer also seen with number of sexual partners, smoking, and young age at first intercourse.
The OCP does not protect against liver cancer (choice E) . The OCP is believed to increase the risk for certain benign liver tumors.
PEARL: There are significant benefits to the use of oral contraceptives; it is estimated that women who use oral contraceptives have a 50% decreased risk for endometrial cancer because of the reduction in the stimulating effect of estrogen and progestin, which prevents the normal proliferative endometrium from progressing to hyperplasia. Because normal ovulation is interrupted by using oral contraceptives, these agents also are known to lessen the risk for ovarian cancer.
