Breast cancer is currently the leading cause of common women cancers in Taiwan.
Familial breast cancer accounts for only 5-10% of all breast cancers. The breast
cancer risk is likely to be explained by a polygenic model where breast cancer
susceptibility is conferred by a large number of low-penetrance alleles of genes
involving DNA repair pathway. The exposure to estrogen predisposes to DNA
damage and mutation to become the modifying factor of breast cancer risk. The
metabolites of estrogen cause DNA damage resulting in genomic instability. The
subtle defect of the DNA repair pathway genes has no complete capacity for DNA
repair. The accumulated DNA defects combined with environmental estrogen
exposure predispose to breast tumorigenesis.