Variation in the risk for liver and gallbladder cancers in socioeconomic and occupational groups in Sweden with etiological implications.

OBJECTIVES: To examine the associations between socioeconomic/occupational factors and liver cancer at various anatomic sites (including primary liver, gallbladder and other cancers).
METHODS: We carried out a follow-up study on the economically active Swedish population, based on the Swedish Family-Cancer Database. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated in different social classes and occupations.
RESULTS: For primary liver cancer, farmers were at a decreased risk; increased risks were observed for male sales agents, journalists, seamen, waiters, cooks and female beverage manufacture workers. Similar patterns were observed for gallbladder cancer; workers employed as journalists, sales agents, cooks and stewards, and public safety workers showed increased risk. Only male transport workers showed increased risk of cancers in other parts.
CONCLUSIONS: Occupations with high consumption of alcohol and/or high prevalence of smoking associated with a risk of liver and gallbladder cancers. The present study suggests that the effects of socioeconomic factors on liver cancer of different subsites are similar; alcohol drinking is a risk factor of gallbladder cancer because of the covariation of primary liver and gallbladder cancers in occupational groups.