The association between breastfeeding and breast cancer occurrence among Israeli Jewish women: a case control study.

Purpose: Breast cancer remains the major malignant disease among Israeli women, with about 4,000 new cases diagnosed annually, and a steadily increasing incidence rates. Early in this century investigators noted that nulliparity and a history of never having breastfed were more common in women with breast cancer than without the disease. Epidemiological evidence on those issues remains controversial. The purpose of this study was to clarify those controversial.
Methods: A hospital-based case control study was carried out at Nahariya hospital (North of Israel) to assess the risk of breast cancer in relation to breastfeeding history. A total of 256 recent cases of breast cancer (diagnosed between January 1999 and February 2005) and 536 controls were included. Detailed information regarding breastfeeding, menstruation, reproductive factors and confounders was collected. Adjusted odds ratios and 95% confidence intervals were calculated.
Results: Short duration of lifetime breastfeeding, late age at first breastfeeding and experience of insufficient milk were found to increase breast cancer risk. When women who had ever breastfed their infants were compared with females who had not, breastfeeding was found to be protective (OR of 0.39; 95% CI 0.26-0.59).
Conclusions: These findings may have significant impact on intervention planning aimed towards breast cancer reduction among Israeli Jewish women.