Cancer risks in patients with vitiligo: a Mendelian randomization study

Few studies have investigated the relationship between vitiligo and risks of various types of cancers, especially those other than skin cancer. Conventional observational studies are susceptible to potential confounders and inverse causation. With a Mendelian randomization approach, we were able to evaluate the causality between vitiligo and different cancer risks. 37 vitiligo-related single-nucleotide polymorphisms identified by the published genome-wide association studies were used as instrumental variables in our study. Summary data of individual-level genetic information were obtained from corresponding studies and cancer consortia. A total of 246,706 cases and 1,021,154 controls were included. The inverse variance-weighted method was applied to estimate the causation between vitiligo and different cancers. The results revealed that vitiligo patients were at lower risks of lung cancer [odds ratio (OR) 0.9513; 95% confidence interval (CI) 0.9174–0.9864; p = 0.0070], breast cancer (OR 0.9827; 95% CI 0.9659–0.9997; p = 0.0468), ovarian cancer (OR 0.9474; 95% CI 0.9271–0.9682; p < 0.001), melanoma (OR 0.9983; 95% CI 0.9976–0.9990; p < 0.001), non-melanoma skin cancer (OR 0.9997; 95% CI 0.9995–0.9999; p < 0.001), kidney cancer (OR 0.9998; 95% CI 0.9996–1.0000; p = 0.0212), and liver cancer (OR 0.9999; 95% CI 0.9999–1.0000; p = 0.0441), while no correlation was observed for other cancer types. Vitiligo was causally associated with reduced risks of several cancers, suggesting that vitiligo-associated autoimmune process might play a role in the suppression of cancer.