Effect of lifestyle and reproductive factors on the onset of breast cancer in female BRCA 1 and 2 mutation carriers.
Mol Genet Genomic Med. 2016 Mar ;4(2):172-7. Epub 2015 Dec 10. PMID: 27066510
BACKGROUND: The birth year-dependent onset of breast cancer (BC) in BRCA1/2 mutation carriers suggests a risk-modifying role for reproductive and life style factors. We therefore examined possible associations between these factors and age at diagnosis.
METHODS: Cox regression analysis and log-Rank testing were used to estimate the effect of potential life style factors on the onset of BC in 197 BRCA mutation carriers.
RESULTS: Nulliparous BRCA mutation carriers developed BC earlier than those who had delivered (36.4 vs. 40.9; P = 0.001). Similarly, smokers and women who had used oral contraceptives experienced an earlier cancer onset (39.0 vs. 41.4; P = 0.05 and 39.3 vs. 44.9; P = 0.0001, respectively). In multivariate analysis, oral contraceptive use (HR: 1.7; P = 0.006) and birth cohort (
CONCLUSION: We here demonstrate that in BRCA1/2 mutation carriers the birth cohort-associated differences in the onset of BC are profound and influenced by reproductive factors.