Cigarette smoking and primary liver cancer: A population-based case-control study in US men

Objective: Using the case-control data from the Selected Cancers Study, the authors assessed whether cigarette smoking increases the risk of primary liver cancer in the US. Methods: Cases were men who were pathologically diagnosed with primary liver cancer during 1984-1988, were 31-59 years old, and lived in the areas covered by eight US cancer registries (n = 168). Controls were men without a history of primary liver cancer who were selected by random-digit telephone dialing (n = 1910). Results: Relative to non-smokers, the risks of liver cancer were 1.85 (95% confidence interval (CI), 1.05-3.25) and 1.49 (95% CI, 0.83-2.68) for former and current smokers, respectively. The adjusted odds ratio (OR) estimates were 0.96, 1.43, 1.80, and 1.87 for smoking for less than 15, 15-24, 25-34 and 35 or more years, respectively (p for trend = 0.039). The OR estimates were 1.41 (95% CI, 0.74-2.68), 1.67 (95% CI, 0.93-2.98), and 1.83 (95% CI, 0.89-3.76) for less than 1, 1-2, and 2 or more packs smoked per day (p for trend = 0.068). Conclusions: Cigarette smoking may be a factor that contributes somewhat to the occurrence of primary liver cancer among men in the United States, a country with low risk of liver cancer.