Hydroxychloroquine and risk of development of cancers: a nationwide population-based cohort study

Background: Hydroxychloroquine (HCQ), one of the disease-modifying antirheumatic drugs, may lead to an inhibition of autophagy. Autophagy, an intracellular self-defense mechanism for the lysosomal degradation of cytoplasmic components such as damaged organelles, plays a role in protecting against neoplasm growth but is also vital for cancer cells due to an increased intracellular metabolic waste. Methods: Taiwan National Health Insurance Database was subjected to analysis to investigate the effect of HCQ exposure on cancer risk in patients with autoimmune diseases. Cancer incidence between patients with or without at least 12-month HCQ use was compared by propensity score-matched landmark analysis. A total of 100,000 participants were enrolled, including 7,662 patients who were diagnosed with autoimmune diseases between January 1, 2000, and December 31, 2012. Results: After propensity score matching, HCQ user and nonuser groups consist of 1,933 patients with a mean follow-up time of 7.82 and 6.7 years, respectively. During the follow-up period, 93 HCQ users and 77 HCQ nonusers developed cancers. Meanwhile, Kaplan-Meier estimates showed no difference in the overall incidence of cancer between HCQ users and nonusers. Conclusion: This propensity score-matched study of Taiwanese patients with autoimmune diseases suggested that HCQ exposure did not increase the cancer risk.