This patient should undergo testing for Lynch syndrome (also known as hereditary nonpolyposis colon cancer). Because she has a personal history of both ovarian and endometrial cancer, as well as a family history of colon and endometrial cancer, her ovarian cancer is likely related to inheriting one of the genetic mutations present in patients with Lynch syndrome. This is an autosomal dominant cancer susceptibility syndrome caused by a germline mutation in one of the DNA-mismatch repair genes (MLH1, MSH2, and MSH6 being the most common). Patients have an increased risk for several types of cancer, usually with early onset. The most common are a 70% risk for colon cancer, 27% to 71% risk for endometrial cancer, and 3% to 14% risk for ovarian cancer. Less common cancers include tumors of the upper urinary tract, bladder, stomach, small bowel, gallbladder, pancreas, brain, and sebaceous glands. Endometrial or, less often, ovarian cancer, can be the sentinel cancer in a patient with Lynch syndrome. Although identification of a Lynch syndrome mutation will not change the management of this patient's ovarian cancer, it will change screening for other cancers, including the need for colonoscopy every 1 to 2 years, annual skin examinations, and consideration of screening upper endoscopy. In addition, if she has Lynch syndrome, genetic testing should be offered to her first-degree relatives, with testing offered in addition to more distant relatives if first-degree relatives are unavailable or unwilling to be tested.

Based on National Comprehensive Cancer Network guidelines, all patients with ovarian cancer are eligible for BRCA1/2 testing. Patients with BRCA1/2 mutations are at risk for other cancers, particularly breast cancer, and additional screening and prophylaxis options should be discussed. In addition, patients with BRCA1 mutations are eligible for clinical trials of agents that are particularly effective in BRCA1-related recurrent ovarian cancers, such as PARP inhibitors. If this patient does not have a Lynch syndrome–related mutation, testing for a BRCA1/2 mutation would be recommended. However, because of her family and personal history of colon and endometrial cancers, testing for Lynch syndrome mutations is recommended first.

Serial abdominal/pelvic CT scans are not recommended to monitor patients with ovarian cancer. CT scans should be reserved for patients with symptoms or with recurrence of cancer based on clinical examination or elevated serum CA-125 levels.

Guidelines differ as to whether to monitor serum CA-125 levels in patients after treatment for ovarian cancer, and this should be discussed with individual patients. In one trial, patients with ovarian cancer treated with first-line platinum-based chemotherapy were randomized to receiving early treatment for ovarian cancer recurrence based on an increasing serum CA-125 level alone versus delaying treatment until clinical symptoms developed. Although patients in the early treatment arm started chemotherapy an average of 4.8 months earlier, there was no difference in overall survival.