Figure 37.8 Ovarian cancer incidence: distribution by age. (From Nagy K. The side effects of managed care on the drug industry. J Natl Cancer Inst 1995;87:1280, with permission.) and duration of the reproductive career (32,33). Early menarche and late menopause increase the risk of ovarian cancer (33). These factors and the relationship of parity and infertility to the risk of ovarian cancer led to the hypothesis that suppression of ovulation may be an important factor. Theoretically, the surface epithelium undergoes repetitive disruption and repair. It is thought that this process might lead to a higher probability of spontaneous mutations that can unmask germline mutations or otherwise lead to the oncogenic phenotype (see Chapter 6).
Prevention Because parity is inversely related to the risk of ovarian cancer, having at least one child is protective for the disease, with a risk reduction of 0.3 to 0.4. Oral contraceptive use reduces the risk of epithelial ovarian cancer (32). Women who use oral contraceptives for 5 or more years reduce their relative risk to 0.5 (i.e., there is a 50% reduction in the likelihood of development of ovarian cancer). Women who had two children and used oral contraceptives for 5 or more years have a relative risk of ovarian cancer as low as 0.3, or a 70% reduction (34). The oral contraceptive pill is the only documented method of chemoprevention for ovarian cancer, and it should be recommended to women for this purpose. When counseling patients regarding birth control options, this important benefit of oral contraceptive use should be emphasized. This is important for women with a strong family history of ovarian cancer.
The performance of a prophylactic salpingo-oophorectomy significantly reduces, but does not totally eliminate, the risk of nonuterine pelvic cancers; because the entire peritoneum is at risk, peritoneal carcinomas can occur in 2% to 3% of women even after prophylactic bilateral salpingo-oophorectomy (25,28).
A thorough discussion of the risks and benefits of oophorectomy should be undertaken in premenopausal women who are undergoing a hysterectomy for benign disease, who do not carry germline mutations, and do not have a family history that suggests that they are at higher than average risk for ovarian cancer (35). The ovaries may provide protection from cardiovascular disease and osteoporosis, and long-term mortality may not be decreased by the performance of prophylactic oophorectomy in women at population risk of ovarian cancer (36).
Screening The value of tumor markers and ultrasonography to screen for epithelial ovarian cancer is not established by prospective studies. Screening results with transabdominal ultrasonography are encouraging in postmenopausal women, but specificity is limited (37–39). Advances in transvaginal ultrasonography showed a very high (>95%) sensitivity for the detection of early-stage ovarian cancer, although this test alone might require performance of as many as 10 to 15 laparotomy procedures for each case of ovarian cancer detected (37,38). Routine annual pelvic examinations have disappointing results in the early detection of ovarian cancer (40). Transvaginal color ﬂow Doppler to assess the vascularity of the ovarian vessels is a useful adjunct to ultrasonography, but it is not useful in screening (41,42).