A cohort study was conducted to assess the association between occupation x and incidence of liver cancer. The study assessed for the presence of additive and multiplicative interaction between occupation and cigarette smoking status. Cumulative incidence and attributable and relative risk for the association between occupation X and liver cancer by smoking status Liver cancer cumulative Attributable incidence risk Relative risk /1000 /1000 Smoking Smoking Smoking Occupation X No Yes No Yes No Yes No 15.2 129.8 A B E F Yes 49.3 216.3 C D G H