Hair Relaxer Use and Breast Cancer Risk by Tumor Molecular Subtypes

The study investigated the association between hair relaxer use and breast cancer risk among women of West African ancestry, focusing on different tumor molecular subtypes. Conducted as part of the Ghana Breast Health study, it included 1,071 breast cancer cases and 2,106 controls. Results indicated that former users of hair relaxers had an increased risk of breast cancer across all subtypes compared to never users, with odds ratios ranging from 1.21 to 3.66. However, there was no statistical evidence of etiologic heterogeneity by subtype, suggesting that relaxer use does not explain subtype-specific breast cancer risk patterns. The study recommends pooling data from multiple studies to enhance power and further investigate the formulations of relaxer products to understand potential carcinogenic mechanisms.