DNA Signalling/Repair Genetic Polymorphisms and BreastCancer Risk: a Review

ABSTRACT

Breast cancer is the leading cause of death among women in developing countries. In Portugal, it presents the highestincidence and mortality rates in women diseases. About 10% of breast cancer is inherited, presenting a family pattern ofincidence, and have been attributable to mutations in high penetrance susceptibility genes, such as BRCA1 and BRCA2.However, BRCA1 and BRCA2 mutations account only for around 25% of families with inherited breast cancer. Many environmentalfactors have been associated with risk of breast cancer development, such as ionized radiation, chemical carcinogens (diet andenvironment). These mutagens sources, together with endogenous and exogenous estrogens, produce a range of DNA lesionssuch as reactive oxygen species, oxidized bases, bulky DNA adducts and DNA strand breaks. Therefore, DNA repair capacitydetermines cellular susceptibility to endogenous and exogenous substances and factors. The response of cells to DNA damageand their ability to maintain genomic instability by DNA repair are crucial in preventing cancer initiation and progression. Somestudies have demonstrated a strong association of higher levels of DNA damage and lower DNA repair capacity in breast cancerpatients and healthy women with a positive family history of breast cancer. Several polymorphisms have been described in DNAsignalling and repair genes. Therefore, although each polymorphism may be associated with a small increased risk for breastcancer in an individual, the risk attributable in the population as a whole is likely to be higher than for rare, high-penetrancesusceptibility genes. In this review, we intend to illustrate the state of the art in studies concerning DNA signalling or repairgenetic polymorphisms and breast cancer susceptibility.