Impact of menstrual and reproductive factors on breast cancer risk in Tunisia: a case-control study.

This report examined the relationship between menstrual and reproductive factors and breast cancer risk. The case-control study was conducted on 400 women with histological confirmed breast cancer operated during the 2006-2009 period at Farhat Hached University Hospital, Sousse, Tunisia, and 400 cancer-free controls, aged 25-75 years. The menstrual and reproductive history was assessed using a structured questionnaire. Odds ratios (ORs), 95 % confidence intervals (CI) and a full confounding assessment, included in this analysis, were derived using logistic regression. A positive family history of breast cancer was associated with a significantly increased risk of breast cancer (OR = 5.15, 95 % CI 1.48-17.94). Significant risk reduction was found with later age at menarche (P = 0.02). There was an insignificant increase in risk with later age at menopause (≥ 51 years; OR = 1.87), later age at first live birth (≥ 26 years; OR = 1.76) and nulliparous women compared to parous women (OR = 2.35). An insignificant decrease in risk was observed with increasing parity number (≥ 3 delivery; OR = 0.86). A significantly reduced risk of breast cancer was found for those women whose lifetime duration of breastfeeding was 73-108 months and for those who breastfed for ≥ 109 months (P = 0.00). Our findings suggest that age at menarche and breastfeeding history have great effects on breast cancer risk among Tunisian women.