Purpose. We evaluated whether hair products, including many known to contain carcinogens and endocrine disrupting chemicals, are related to incident ovarian cancer in a large prospective cohort. Methods. After excluding women with a history of ovarian cancer or bilateral oophorectomy, 40,559 Sister Study participants were included. Participants were aged 35–74 and had a sister with breast cancer but no history of breast cancer themselves at enrollment in 2003–2009. Participants completed questionnaires on frequency of hair product use (including hair dyes, straighteners/relaxers and hair permanents/body waves) in the 12 months prior to enrollment. Cox regression models were used to estimate adjusted hazard ratios (HRs) and 95% Confidence Intervals (CIs) for the association between hair product type and frequency of use in relation to incident ovarian cancer. We also assessed models stratified by tumor type (serous, non-serous). Results. After a mean of 10 years of follow-up, 241 women had self-reported an incident ovarian cancer diagnosis. Ever use of hair products in the past year (including permanent, semi-permanent and temporary hair dyes, straighteners/relaxers, and hair permanents/body waves) was not associated with a higher risk of ovarian cancer. However, frequent use (>4 times) of straighteners/relaxers in the past year was positively associated with ovarian cancer (HR = 2.45, 95% CI: 1.27–4.73). This association was stronger for non-serous (HR = 4.25, 95% CI: 1.07–16.9) compared to serous (HR = 1.38, 95% CI:0.47–4.04) ovarian cancers. Ever use of permanent hair dye was positively associated with non-serous (HR = 1.91, 95% CI, 1.10–3.33), but inversely associated with serous (HR = 0.65, 95% CI: 0.43–0.98) ovarian cancer (p-for-heterogeneity = 0.002). Conclusion. These results suggest that frequent use of hair straighteners/relaxers and possibly permanent hair dye may be positively associated with the occurrence of non-serous ovarian cancers.
The following are the 23 highest scoring abstracts of those submitted for presentation at the 45th Annual ASPO meeting held virtually March 29 – April 1, 2021.