Hannibal CG, et al. - In this nationwide case-control study, risk of serous borderline tumor (SBT) or mucinous borderline tumor (MBT) related to the use of paracetamol, low-dose aspirin, or non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) was assessed by using the Danish Pathology Data Bank, 1997–2015. Per case, 15 controls were randomly selected by using risk-set sampling. Women with previous cancer (except non-melanoma skin cancer) and controls with bilateral oophorectomy/salpingo-oophorectomy were excluded. Using nationwide registries, they retrieved information on redeemed prescriptions of medications/confounders. Findings revealed no strong relationships between the studied medications and ovarian borderline tumors. Nevertheless, a possible chemopreventive effect of recent paracetamol use on MBTs could be suggested by the findings, while neither low-dose aspirin nor non-aspirin NSAIDs use seemed protective against SBTs or MBTs.