Use of Underarm Cosmetic Products in Relation to Risk of Breast Cancer: A Case-Control Study

Background Previous studies on breast cancer (BC), underarm cosmetic products (UCP) and aluminum salts have shown conflicting results. We conducted a 1:1 age-matched case-control study to investigate the risk for BC in relation to self-reported UCP application. Methods Self-reported history of UCP use was compared between 209 female BC patients (cases) and 209 healthy controls. Aluminum concentration in breast tissue was measured in 100 cases and 52 controls. Multivariable conditional logistic regression analysis was performed to estimate odds ratios (ORs) with 95% confidence intervals (CIs), adjusting for established BC risk factors. Findings Use of UCP was significantly associated with risk of BC (p = 0.036). The risk for BC increased by an OR of 3.88 (95% CI 1.03–14.66) in women who reported using UCP's several times daily starting at an age earlier than 30 years. Aluminum in breast tissue was found in both cases and controls and was significantly associated to self-reported UCP use (p = 0.009). Median (interquartile) aluminum concentrations were significantly higher (p = 0.001) in cases than in controls (5.8, 2.3–12.9 versus 3.8, 2.5–5.8 nmol/g). Interpretation Frequent use of UCPs may lead to an accumulation of aluminum in breast tissue. More than daily use of UCPs at younger ages may increase the risk of BC.
Highlights • Frequent use of underarm cosmetic products may be related to incorporated aluminum concentration in breast tissue. • Use of underarm cosmetic products several times a day at younger ages may increase the risk of breast cancer. Previous studies regarding breast cancer (BC) risk and underarm cosmetic products (UCPs) with aluminum salts have shown conflicting results. Here we provide comprehensive information about the use of UCPs and aluminum measurements in breast cancer patients and healthy individuals. The findings suggest that the frequent use of UCPs lead to an accumulation of aluminum in breast tissue. We observed an increased risk for BC in women who reported to use UCPs more than once daily starting at an age