Cancer Previvors in an Active Duty Service Women Population: An Opportunity for Prevention and Increased Force Readiness

Background: The majority of active duty service women (ADS) are young, have access to healthcare, and meet fitness standards set by the U.S. military, suggesting that ADS represent a healthy population at low risk of cancer. Breast cancer is, however, the most common cancer in ADS and may have a significant effect on troop readiness with lengthy absence during treatment and inability to return to duty after the treatment. The identification of unaffected ADS who carry germline mutations in cancer predisposition genes ("previvors") would provide the opportunity to prevent or detect cancer at an early stage, thus minimizing effects on troop readiness. In this study, we determined (1) how many high-risk ADS without cancer pursued genetic testing, (2) how many previvors employed risk-reducing strategies, and (3) the number of undiagnosed previvors within an ADS population.

Methods: The Clinical Breast Care Project (protocol WRNMMC IRB #20704) database of the Murtha Cancer Center/Walter Reed National Military Medical Center was queried to identify all ADS with no current or previous history of cancer. Classification as high genetic risk was calculated using National Comprehensive Cancer Network 2019 guidelines for genetic testing for breast, ovary, colon, and gastric cancer. The history of clinical genetic testing and risk-reducing strategies was extracted from the database. Genomic DNA from ADS with blood specimens available for research purposes were subjected to next-generation sequencing technologies using a cancer predisposition gene panel.

Results: Of the 336 cancer-free ADS enrolled in the Clinical Breast Care Project, 77 had a family history that met National Comprehensive Cancer Network criteria for genetic testing for BRCA1/2 and 2 had a family history of colon cancer meeting the criteria for genetic testing for Lynch syndrome. Of the 28 (35%) high-risk women who underwent clinical genetic testing, 11 had pathogenic mutations in the breast cancer genes BRCA1 (n = 5), BRCA2 (n = 5), or CHEK2 (n = 1). Five of the six ADS who had a relative with a known pathogenic mutation were carriers of the tested mutation. All of the women who had pathogenic mutations detected through clinical genetic testing underwent prophylactic double mastectomy, and three also had risk-reducing salpingo-oophorectomy. Two (6%) of the 33 high-risk ADS tested only in the research setting had a family history of breast/ovarian cancer and carried pathogenic mutations: one carried a BRCA2 mutation, whereas the other carried a mutation in the colon cancer predisposition gene PMS2. No mutations were detected in the 177 low-risk women tested in the research setting.

Discussion: Within this unaffected cohort of ADS, 23% were classified as high risk. Although all of the previvors engaged in risk-reduction strategies, only one-third of the high-risk women sought genetic testing. These data suggest that detailed family histories of cancer should be collected in ADS and genetic testing should be encouraged in those at high risk. The identification of previvors and concomitant use of risk-reduction strategies may improve health in the ADS and optimize military readiness by decreasing cancer incidence.