Paracetamol use and risk of epithelial ovarian cancer: A nationwide nested case–control study.

Objective: To investigate whether paracetamol use is associated with a reduced risk of epithelial ovarian cancer (EOC). Design: A nationwide nested case–control study. Setting: Danish female population. Population: A total of 9589 EOC cases diagnosed from 2000 to 2019 were age‐matched with 383 549 randomly selected female controls using risk set sampling. Methods: Paracetamol use, reproductive history, history of medication and history of surgery were retrieved from Danish national registers. Paracetamol use was defined as at least two prescriptions for up to 1 year before the index date, and was further classified according to recency, duration, cumulative dose and intensity of dose. Main outcome measures: Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals for the association between paracetamol and EOC risk, overall and by histological subtypes. Results: 'Ever' use of paracetamol was associated with a reduced EOC risk after adjusting for potential confounding factors (OR 0.92, 95% CI 0.87–0.97). The association was only significant among recent users (OR 0.89, 95% CI 0.84–0.95). The risk declined further with the increasing level of cumulative dose and intensity; women from the group with a high cumulative dose and a high intensity had a 13% (OR 0.87, 95% CI 0.80–0.94) and 14% (OR 0.86, 95% CI 0.79–0.93) reduced risk, respectively. In the histological subtype analysis, reduced risk with 'ever' use was most pronounced for serous and clear cell tumours. Conclusions: Paracetamol use was associated with a decreased risk of EOC in a dose–response manner. Future studies are needed to validate the findings and investigate the mechanisms behind the association. [ABSTRACT FROM AUTHOR]