Age and cohort effects in primary liver cancer.

Primary liver cancer incidence data from 30 populations reported in Cancer Incidence in Five Continents were analyzed. After adjustment for time trends, log incidence increases linearly with log age. Liver cancer risk increases more rapidly with age than that of colon cancer, stomach cancer, or lung cancer in non-smokers; it increases less rapidly than that of prostatic cancer or of lung cancer in smokers. Over the past 20 years, most populations have been found to have increasing age-adjusted liver cancer incidence. There is no correlation between change in rates and magnitude of rates. Male rates are higher than female rates and the ratio of the two tends to be higher in high-risk areas.