Breast cancer in Mexican women: an epidemiological study with cervical cancer control

Introduction In Mexico, breast cancer (BC) is one of the main causes of can cer deaths in women, with increasing incidence and mortality in recent year s. Therefore, the aim of the study is identify possible risk factors relate d to BC. Methods An epidemiological study of hospital cases of BC and controls with cervical uterine cancer (CUCA) was carried out at eight third level concent ration hospitals in Mexico City. The total of 353 incident cases of BC and 630 controls with CUCA were identified among women younger than 75 years wh o had been residents of the metropolitan area of Mexico City for at least o ne year. Diagnosis was confirmed histologically in both groups. Variables w ere analyzed according to biological and statistical plausibility criteria. Univariate, bivariate and multivariate analyses were carried out. Cases an d controls were stratified according to the menopausal hormonal status (pre and post menopause). Results The factors associated with BC were: higher socioeconomic level (OR =2.77; 95%CI = 1.77 - 4.35); early menarche (OR= 1.32; 95%CI= 0.88 - 2.00); old age at first pregnancy (>31 years: OR=5.49; 95%CI=2.16 - 13.98) and a family history of BC (OR= 4.76; 95% CI= 2.10 - 10.79). In contrast, an incr ease in the duration of the breastfeeding period was a protective factor (> 25 months: OR= 0.38; 95%CI= 0.20 0.70). Conclusions This study contributes to the identification of risk factors fo r BC described in the international literature, in the population of Mexica n women. Breastfeeding appears to play an important role in protecting wome n from BC. Because of changes in women's lifestyles, lactation is decreasin g in Mexico, and young women tend not to breastfeed or to shorten the durat ion of lactation.