Non-Hodgkin's lymphoma and hepatitis C virus: a case-control study from northern and southern Italy.

HCV has been associated with NHL, but the evidence from case series and case-control studies is not totally consistent. Between 1999 and 2002, we conducted a hospital case-control study on the association between HCV, HBV and NHL in 2 areas of Italy where HCV infection is relatively frequent. Cases (n = 225, median age 59 years) were consecutive patients with a new diagnosis of NHL admitted to local specialized and general hospitals. Controls (n = 504, median age 63 years) were patients with a wide spectrum of acute conditions admitted to the same hospitals as cases. HCV prevalence was 19.6% among NHL cases and 8.9% among controls (adjusted OR = 2.6, 95% CI 1.6-4.3). The ORs for HCV were similar for low-grade and intermediate-/high-grade B-cell NHL (3.2 and 2.4, respectively) as well as for nodal and extranodal NHL (2.7 and 2.6, respectively). Positivity for HBsAg was found in 3.8% of cases and 0.9% of controls (OR = 4.1, 95% CI 1.2-14.4). An elevated OR was also found for history of hepatitis C (OR = 4.7, 95% CI 2.3-9.5). History of blood transfusion before 1990 was associated with HCV positivity among controls but not with NHL risk. In conclusion, HCV infection was associated with an increase in NHL risk, and the fraction of NHL cases attributable to HCV was 12.4% (range 6.3-18.5%).