LAUSR

In contemporary literature, little attention has been paid to the association between coronavirus disease‐2019 (COVID‐19) and cancer risk. We performed the Mendelian randomization (MR) to investigate the causal associations between the three types of COVID‐19 exposures (critically ill COVID‐19, hospitalized COVID‐19, and respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection) and 33 different types of cancers of the European population. The results of the inverse‐variance‐weighted model indicated that genetic liabilities to critically ill COVID‐19 had suggestive causal associations with the increased risk for HER2‐positive breast cancer (odds ratio [OR] = 1.0924; p‐value = 0.0116), esophageal cancer (OR = 1.0004; p‐value = 0.0226), colorectal cancer (OR = 1.0010; p‐value = 0.0242), stomach cancer (OR = 1.2394; p‐value = 0.0331), and colon cancer (OR = 1.0006; p‐value = 0.0453). The genetic liabilities to hospitalized COVID‐19 had suggestive causal associations with the increased risk for HER2‐positive breast cancer (OR = 1.1096; p‐value = 0.0458), esophageal cancer (OR = 1.0005; p‐value = 0.0440) as well as stomach cancer (OR = 1.3043; p‐value = 0.0476). The genetic liabilities to SARS‐CoV‐2 infection had suggestive causal associations with the increased risk for stomach cancer (OR = 2.8563; p‐value = 0.0019) but with the decreasing risk for head and neck cancer (OR = 0.9986, p‐value = 0.0426). The causal associations of the above combinations were robust through the test of heterogeneity and pleiotropy. Together, our study indicated that COVID‐19 had causal effects on cancer risk.