Time trends and age-period-cohort effects on the incidence of primary liver cancer in a well-defined French population: 1976-1995

Background/Aims: There is growing interest worldwide in primary liver cancer. The aim of this study was to describe the incidence of this cancer over a 20-year period in a well-defined French population. Methods: Time trends by 4-year period were studied by sex, age group, place of residence, histological type and associated cirrhosis, Trends were also analysed using the age-period-cohort model. Results: Primary liver cancer incidence in men increased from 7.5/100 000 for the period 1976-79 to 10.2/100 000 for the period 1992-95. The mean annual variation was +2.2% (p<0.05), The increase in incidence was seen mainly in the 55-64 and 65-74 age groups and concerned hepatocellular carcinomas. In men, the increase in incidence rates with time was observed mainly in rural areas, whereas incidence rates in urban areas remained stable. The rise in incidence was due mostly to an increase in primary liver cancer with cirrhosis, in relation to a progressive increase in post-hepatitic cirrhosis and a recent increase in alcoholic cirrhosis, The estimated cumulative risk for the life span 30-74 years increased from 0.8% for the 1904-1908 cohort to 2.1% for the 1934-1938 cohort. There was no significant trend in female rates. Conclusions: In France, incidence rates for primary liver cancer are increasing in men, whilst they are remaining stable in women. Our data confirm the primary importance of alcohol in the aetiology of this cancer. Further studies are necessary to unravel the respective roles of alcohol and hepatitis C virus in the increasing incidence of primary liver cancer.