Smoking and physical inactivity increase cancer prevalence in BRCA-1 and BRCA-2 mutation carriers: results from a retrospective observational analysis

BACKGROUND The aim of this analysis in a pilot study population was to investigate whether we can verify seemingly harmful lifestyle factors such as nicotine and alcohol indulgence, obesity, and physical inactivity, as well as a low socioeconomic status for increased cancer prevalence in a cohort of BRCA 1 and 2 mutation carriers. METHODS The analysis data are derived from 68 participants of the lifestyle intervention study LIBRE-1, a randomized, prospective trial that aimed to test the feasibility of a lifestyle modification in BRCA 1 and 2 mutation carriers. At study entry, factors such as medical history, lifestyle behavior, and socioeconomic status were retrospectively documented by interview and the current BMI was determined by clinical examination. The baseline measurements were compared within the cohort, and presented alongside reference values for the German population. RESULTS Study participants indicating a higher physical activity during their adolescence showed a significantly lower cancer prevalence (p = 0.019). A significant difference in cancer occurrence was observed in those who smoked prior to the disease, and those who did not smoke (p \textless 0.001). Diseased mutation carriers tended to have a lower BMI compared to non-diseased mutation carriers (p = 0.079), whereas non-diseased revealed a significantly higher physical activity level than diseased mutation carriers (p = 0.046). DISCUSSION The present data in this small cohort of 68 mutation carriers suggest that smoking and low physical activity during adolescence are risk factors for developing breast cancer in women with BRCA1 or BRCA2 mutation. Further data of the ongoing LIBRE 2 study are necessary to confirm these findings in a larger cohort of 600 mutation carriers.