Findings in CCHS were supportive of a causal effect of AHRR methylation on lung cancer [HR = 0.30 (95% CI = 0.10, 1.00) per SD], but in two-sample MR this site was not causally implicated [OR = 1.00 (95% CI = 0.83, 1.10) per SD increase]. Here, AHRR is linked to lung cancer.