AFP and hepatocellular carcinoma: As shown, the risk of HCC based on serum AFP levels after adjustment of genetic effects was higher in people with a history of smoking compared to those without a smoking history (OR = 2.15, 95% CI = 1.42–3.26; P < 0.001 vs. OR = 1.19, 95% CI = 1.10–1.30; P < 0.001).