Risk factors for the rising rates of primary liver cancer in the United States

Background: A recent increase in the incidence of hepatocellular carcinoma was reported in the United States. The cause of this witnessed rise remains unknown. Methods: We examined the temporal changes in both age-specific and age-stan dardized hospitalization rates of primary liver cancer associated with hepa titis C, hepatitis B, and alcoholic cirrhosis in the Department of Veterans Affairs Medical Center's Patient Treatment File. Results: A total of 1605 patients were diagnosed with primary liver cancer between 1993 and 1998. The over all age-adjusted proportional hospitalizati on rate for primary liver cancer increased from 36.4 per 100 000 (95% confi dence interval [CI], 34.0-38.9) between 1993 and 1995 to 47.5 per 100 000 ( 95% CI, 44.6-50.1) between 1996 and 1998. There was a 3-fold increase in th e age-adjusted rates for primary liver cancer associated with hepatitis C v irus, from 2.3 per 100 000 (95%, CI, 1.8-3.0) between 1993 and 1995 to 7.0 per 100 000 (95% CI, 5.9-8.1) between 1996 and 1998. Concomitant with this rise, the age-specific rates for primary liver cancer associated with hepat itis C also shifted toward younger patients. During the same periods, the a ge-adjusted rates for primary liver cancer associated with either hepatitis B virus (2.2 vs 3.1 per 100 000) or alcoholic cirrhosis (8.4 vs 9.1 per 10 0 000) remained stable. The rates for primary liver cancer without risk fac tors also remained without a statistically significant change, from 17.5 (9 5% CI, 15.8-19.1) between 1993 and 1995 to 19.0 per 100 000 (95% CI, 17.3-2 0.7) between 1996 and 1998. Conclusions: Hepatitis C virus infection accounts for most of the increase in the number of cases of primary liver cancer among US veterans. The rates of primary liver cancer associated with alcoholic cirrhosis and hepatitis B virus infection have remained stable.