EXPLORATION OF BREASTFEEDING AS A PROTECTIVE FACTOR FOR BREAST CANCER IN SOUTH AFRICAN WOMEN: A NESTED CASE-CONTROL STUDY

Background. South African’s (SA) breast cancer incidence rate is continually increasing (39 per 100,000 (2012) versus 46.2 per 100,000 (2018) with trends towards later-stage diagnosis. In previous literature, breastfeeding has been assessed as a protective factor for breast cancer; however, the SA population experiences inconsistent breastfeeding trends, rates, and support services. Therefore, this study will evaluate the inverse association between breast cancer and breastfeeding history. Methods. Cases (breast cancer) and controls (mastalgia) were matched 1:1 on clinical visit from May-August 2019 at Groote Schuur Hospital (GSH) in Cape Town, Western Cape, South Africa. Breastfeeding history, breast carcinoma diagnosis, and clinically relevant endocrinology data was extracted from GSH medical records. Bivariate conditional logistic regression (clogit) and 2 analyses compared predictor variables amongst breast cancer groups. Multivariable clogit models assessed the association between breast cancer diagnosis and breastfeeding history both unadjusted and adjusted for statistically and clinically relevant confounders. Results. Results. In a sample of 360 SA mothers (mean age= 53 years old, SD= 14.36), 79% of breast cancer patients breast cancer breastfed while 75% of non-breast cancer patients breastfed, with the majority of the population (75%) having ever breastfed overall. When controlling for all other covariates, SA mothers with breastfeeding history did not have a lower risk of breast cancer compared to women who never breastfed with OR=1.29 (95% CI 0.52 – 3.23). Conclusion. This pilot study did not show a protective effect of breastfeeding on breast cancer diagnosis. However, it contributes to the theory that race, ethnicity, and detailed exposure/outcome statuses are essential to concluding statistically, biologically, and clinically significant results for the assessment of a dose response relationships