Breastfeeding reduces breast cancer risk: a case-control study in Tunisia.

In this report, we examined the relationship between mother's breastfeeding history and her risk of breast cancer, in a case-control study in Tunisia between 2006 and 2009. About 400 breast cancer cases and 400 controls were included. Cases and controls were interviewed using a standardized structured questionnaire to obtain information on breastfeeding and other risk factors. Mean duration of breastfeeding per child was significantly associated with a reduced risk of breast cancer for women who breastfed for > 24 months per child. The OR was 0.46 (95% CI, 0.28-0.76) when compared those who breastfed for < 6 months. The test for trend was significant (p = 0.01). A significantly reduced risk of breast cancer was found for those whose lifetime duration of breastfeeding was 73-108 months (OR = 0.65, 95% CI, 0.36- 1.18) and for those who breastfed for > or = 109 months (OR = 0.42, 95% CI, 0.20-0.84). Stratification by menopausal status showed a reduced risk of breast cancer associated with a longer duration of breastfeeding for both pre- and postmenopausal women. The risk reduction was more consistent for lifetime duration of breastfeeding, the test for trend being significant for both pre- (p = 0.03) and postmenopausal (p = 0.01) women. These results support an inverse association between breastfeeding and breast cancer risk.