A clinically structured and partnered approach to genetic testing in Trinidadian women with breast cancer and their families.

INTRODUCTION: Breast cancer (BC) is the leading cause of cancer death in Caribbean women. Across the Caribbean islands, the prevalence of hereditary breast cancer among unselected breast cancer patients ranges from 5 to 25%. Moreover, the prevalence of BC among younger women and the high mortality in the Caribbean region are notable. This BC burden presents an opportunity for cancer prevention and control that begins with genetic testing among high-risk women. Measured response to positive genetic test results includes the number of preventive procedures and cascade testing in family members. We previously reported data on an active approach to promote cascade testing in the Bahamas and report on preventive procedures showing moderate uptake. Here, we describe a clinically structured and community-partnered approach to the dissemination and follow-up of genetic test results including family counseling for the promotion of risk mitigation strategies and cascade testing in our Trinidadian cohort of patients tested positive for BC predisposition genes.

METHODS: As a part of our initial study of BC genetic testing in Trinidad and Tobago, all participants received pre-test counseling including three-generation pedigree and genetic testing for BRCA1/2, PALB2, and RAD51C. The study was approved by the University of Miami IRB and the Ethics Committee of the Ministry of Health, Trinidad and Tobago. We prospectively evaluated a clinically structured approach to genetic counseling and follow-up of BC mutation carriers in Trinidad and Tobago in 2015. The intervention consisted of (1) engaging twenty-nine BC patients with a deleterious gene mutation (probands), and (2) invitation of their at-risk relatives to attend to a family counseling session. The session included information on the meaning of their results, risk of inheritance, risk of cancer, risk-reduction options, offering of cascade testing to family members, and follow-up of proband decision-making over two years.

RESULTS: Twenty-four of twenty-nine mutation carriers (82.8%) consented to enroll in the study. At initial pedigree review, we identified 125 at-risk relatives (ARR). Seventy-seven ARR (62%) attended the family counseling sessions; of these, 76 ARR (99%) consented to be tested for their family gene mutation. Genetic sequencing revealed that of the 76 tested, 35 (46%) ARR were carriers of their family mutation. The ARR received their results and were urged to take preventative measures at post-test counseling. At 2-year follow-up, 6 of 21 probands with intact breasts elected to pursue preventive mastectomy (28.5%) and 4 of 20 women with intact ovaries underwent RRSO (20%).

CONCLUSIONS: In Trinidad and Tobago, a clinically structured and partnered approach to our testing program led to a significant rate of proband response by completing the intervention counseling session, executing risk-reducing procedures as well as informing and motivating at-risk relatives, thereby demonstrating the utility and efficacy of this BC control program.