Abstract
BACKGROUND: Little is known about how members of cancer-prone families think about genetic determinism and whether personal behavior can amplify or counter genetic risk for disease. PURPOSE: Understanding how people think about the impact of personal behavior on disease risk may inform communications about genetic risks and their management. METHODS: We assessed three sets of beliefs about the impact of behavior on genetic risk-interactive (unhealthful behaviors can amplify genetic risk), subtractive (healthful behaviors can reduce genetic risk), and deterministic (genes primarily determine health outcomes)-among 114 unaffected members of melanoma-prone families receiving genetic counseling (51.6% men, average age = 35.3). We examined whether these beliefs predicted changes in perceived control, motivation to manage melanoma risk, and sun-protection behavior one year later. RESULTS: Participants strongly endorsed interactive and subtractive beliefs, but not deterministic beliefs. These beliefs generally did not change, even among those who received positive CDKN2A/p16 genetic test results conferring up to 76% lifetime melanoma risk. Controlling for age, sex, education, skin type, and genetic test result, interactive beliefs predicted sustained increases in perceptions of personal control, motivation to reduce sun exposure, use of multiple sun-protection methods, and reduction in objectively assessed tanning at the wrist one year following genetic counseling. Subtractive beliefs predicted increased personal control, motivation to manage risk, and sunscreen use, while deterministic beliefs were generally unrelated to outcomes. CONCLUSIONS: Among people at highly elevated hereditary cancer risk, beliefs that unhealthful behaviors can amplify genetic risk seem to be especially motivating of behavioral risk-reduction efforts.