HCV infection increases the risk of lymphoma-like cancers

Hepatitis C virus (HCV) infection doubles the relative risk of lymphoid neoplasms, according to Taiwanese research published in Hepatology. Investigators compared the incidence of lymphoma-like cancers between matched people with and without HCV; after taking onto account all potential confounders, HCV infection was associated with a twofold increase in the risk of any lymphoid neoplasm, with a similar increase in the risk of non-Hodgkin's lymphoma (NHL).

“We conducted a nationwide population-based cohort study to reduce the possibility of selection bias,” write the authors. “We demonstrated that HCV infection is associated with a higher risk of any lymphoid neoplasm, especially NHL, after adjustment for potential confounding variables.”

Lymphoid neoplasms include non-Hodgkin's lymphoma, Hodgkin's lymphoma, multiple myeloma, acute lymphoblastic lymphoma and chronic lymphocytic leukaemia. There are some data suggesting that chronic HCV infection increases the risk of such malignancies. However, studies examining this association have had a small sample size and a short period of follow-up.

To establish a clearer understanding of the link between HCV infection and the risk of lymphoid-neoplasms, investigators in Taiwan designed a prospective cohort involving people with and without HCV. Patients and controls were matched according to age, sex and co-morbidity. Data were gathered on the incidence of any lymphoid neoplasm and non-Hodgkin's lymphoma over six to eight years of follow-up. The authors conducted a series of analyses to see if HCV infection increased the risk of these cancers.

The cohort of people with HCV comprised 11,679 individuals who were diagnosed with the infection between 2001 and 2005. They were matched with 46,716 people who did not have HCV. Previous cancer, infection with hepatitis B virus and infection with HIV were exclusion criteria.

Mean age was 55 years and 51% of individuals in both cohorts were female. The mean duration of follow-up was six years for the cohort with HCV and eight years for the cohort without HCV.

During this time, 36 people in the HCV cohort and 83 people in the non-HCV cohort were diagnosed with lymphoid neoplasms. Most of these were non-Hodgkin's lymphoma (77% in HCV cohort; 80% non-HCV cohort).

The incidence rate for any lymphoid-neoplasm was significantly higher in the HCV cohort compared to the non-HCV cohort (48 vs 22 per 100,000 person-years; p < 0.0001).

Incidence of non-Hodgkin lymphoma was also higher in the HCV cohort than in the non-HCV cohort (37 vs 17.5 per 100,000 person-years; p = 0.0008).

Average time from entry into follow-up and diagnosis with a malignancy was significantly shorter for the HCV patients compared to people in the non-HCV group (3.1 vs 4.6 years; p = 0.002).

After controlling for potential confounders, HCV infection was associated with a more than twofold increase in the risk of any lymphoid-neoplasm (HR = 2.30; 95% CU, 1.55-3.43; p < 0.0001) and a two-fold increase in the risk of non-Hodgkin's lymphoma (HR = 2.00; 95% CI, 1.27-3.16; p < 0.003). These findings remained robust in a sensitivity analysis that excluded people who developed cancer within the first year after recruitment and also in an analysis that included people with HIV.

There were some data suggesting that HCV therapy reduces the risk of lymphoid-neoplasms. Overall, 9% of people with HCV received interferon-based therapy. Incidence of any lymphoid-neoplasm was 16 per 100,000 person-years in these patients compared to 52 per 100,000 person-years in people who were not treated. None of the treated patients developed non-Hodgkin's lymphoma, but incidence of this cancer was 41 per 100,000 person-years in the patients who did not receive therapy.

“This nationwide population-based cohort study with longitudinal follow-up found that HCV infection is associated with a greater risk of lymphoid-neoplasms, especially NHL,” conclude the investigators. “Additional large studies are necessary to explore whether anti-HCV therapy can reduce the incidence of lymphoid neoplasms.”