Tranexamic acid use is not associated with the risk of melanoma in Danish women: A nested case-control study using Danish health registries

Background: Repurposing already approved drugs in a cancer setting has gained increasing interest in recent years. Tranexamic acid is an anti-fibrinolytic drug that has recently been suggested as an anti-cancer drug due to its anti-inflammatory and anti-carcinogenic effects in animal studies. In this study, we aimed to investigate the possible melanoma-preventive role of tranexamic acid in Danish women.Method: In this nested case-control study, we identified female cases 18-60 years with first-time melanoma during 2000-2015 and age-matched them with 10 female controls. The odds ratio (OR) of melanoma with tranexamic acid ever-or high use (>= 100,000 mg) was estimated using conditional logistic regression.Results: A total of 7986 women with incident melanoma were eligible for study inclusion and were matched to 79,860 controls. Most exposed cases and controls were exposed to low cumulative doses of tranexamic acid corresponding to around 5 days of continuous treatment (1000 mg 3 times daily) for the presumed main indication, i.e., menorrhagia.The crude OR associating tranexamic ever use with melanoma was 1.04 (95% CI 0.98-1.11, p = 0.20), and the adjusted OR was 1.03 (0.97-1.10, p = 0.32). We found no dose-response pattern or effect measure modification by age, histologic type, localization, or clinical stage. However, prolonged use with cumulative doses of tranexamic acid (>= 100,000 mg) was associated with an increased risk of melanoma (adjusted OR 1.23,95 %, CI 0.96-1.56), compared with non-use. Conclusion: We found no association between tranexamic acid use and the risk of melanoma in Danish women. This could be explained by underlying dose-or biological factors, and sporadic use patterns. A higher risk of melanoma was seen among prolonged users which could be due to surveillance bias.