Risk factors of breast cancer in Mexican women

Objective. To investigate the association between family history (FH) of ne oplasia, gyneco-obstetric factors and breast cancer (BC) in a case-control study. In cases, to analyze those variables in relation with early onset of BC, the manner of detection (self-examination, prompted by pain, or casual ), the size of tumor, and the elapsed time to seek medical attention. Mater ial and methods. Data from 151 prevalent BC cases and 235 age-matched contr ols were analyzed by multiple logistic regression, to assess the influence of BC risk factors. Results. Ten per cent of patients and 1% of controls ha d first-degree relatives (FDR) with BC. Family history of FDR with BC (OR, 11.2; 95% Cl 2.42-51.92) or with gastric or pancreatic cancer (OR, 17.7; 95 % CI 2.2-142.6) was associated with BC risk. Breastfeeding at or under 25 y ears of age was protective against BC (OR, 0.40; 95% CI 0.24-0.66). The man ner of tumor detection did not influence its size at the time of diagnosis. Conclusions. Our study confirms that FH of BC and/or of gastric or pancrea tic carcinoma are risk factors for BC, while lactation at 25 years of age o r earlier is protective.