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How should women with a genetic predisposition for cancer be managed?

William J. Hoskins, MD A 10% of ovarian cancers, 10–12% of colorectal cancers, and 5% of endometrial cancers result from hereditary predisposition. Identification of women who may be at increased risk of these cancers because they have a genetic mutation is very important because of their high risk of developing one of these cancers. Women with a mutation in BRCA1 or BRCA2 have a 50–85% risk of breast cancer. Women with a BRCA1 mutation have a lifetime risk for ovarian cancer of 30–40% and women with a BRCA2 have a 15–25% risk of ovarian cancer.1 These women also carry some increased risk of pancreatic, gall bladder, and stomach cancers. Women with Lynch syndrome (hereditary nonpolyposis colorectal cancer) have a 40–60% risk of colorectal cancer, a 40–60% risk of endometrial cancer, and a 5–10% risk of ovarian cancer.1 These cancers are due to mutations in the mismatch repair genes MSH2, MSH1, and possibly MSH6. Women with these mutations also carry an increased risk of other cancers, such as upper gastrointestinal, pancreatic, upper urinary tract, and brain. Although only approximately 15% of an obstetrician–gynecologists’ patients may carry a genetic mutation that makes them more susceptible to some type of cancer, identification of those patients so that they may have regular cancer screening or, as discussed in the article by Chen et al2 (see p. 18), risk-reducing surgery is very important. A thorough family history must be a part of the initial evaluation of every patient. Patients with a clustering of cancers or early-onset cancers in their family should be referred to a genetic counselor and perhaps to a medical geneticist. Identification of a genetic predisposition for cancer not only benefits the patient herself but her extended family. Once an individual is identified as having a cancer-predisposing genetic mutation, she can be counseled as to the option of a screening regimen compared with risk-reducing surgery. In the article by Chen et al2 in this issue of Obstetrics & Gynecology, the authors have developed a decision analytic model to evaluate a theoretical population of 10,000 women with Lynch syndrome in each of three clinical scenarios: 1) lifetime annual gynecologic examinations (control group); 2) annual surveillance with gynecologic examination, pelvic ultrasound, endometrial biopsy, and serum CA 125 testing; and 3) risk-reducing hysterectomy and bilateral salpingo-oophorectomy at age 30 years. They used literature-based estimates of success for the surveillance tests and for the surgical intervention. They used Surveillance, Epidemiology and End Results data to estimate cancer mortality and outcomes based on stage of disease at diagnosis. They estimated that 18.4% of the surveillance group would be diagnosed with endometrial cancer and 3.7% with ovarian cancer at the time of surgery for a positive surveillance test. In the annual examination (control) group, they estiSee related article on page 18.