Filling in the gap on prevalence of viral infections

There is ongoing debate over whether universal screening for hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV should be conducted for newly diagnosed cancer patients. While there are potential benefits and detriments to routine screening, the prevalence of infection with these three viruses in newly diagnosed cancer patients is not known. With this key information lacking, it is difficult to fully assess whether a universal screening program should be recommended. Dr. Scott Ramsey from the Division of Public Health Sciences and Director of Hutchinson Institute for Cancer Outcomes Research (HICOR) and colleagues conducted a nationwide, multicenter study to address this gap and estimate the prevalence of HBV, HCV, and HIV in newly diagnosed cancer patients in the U.S. Their results were recently published in the journal JAMA Oncology.

Participants for this cohort study were recruited from 41 cancer clinics affiliated with SWOG Cancer Research Network. Eligible patients could enroll into the study if they were within four months of a new cancer diagnosis; a total of 3051 patients joined during the approximately three and a half year recruitment period. Enrolled participants were either tested for previous HBV, chronic HBV, HCV, and HIV or provided documentation of testing for these viruses within the previous year. Participants also completed a questionnaire to assess demographics and risk factors for infection with the viruses.

The authors also assessed what proportion of cases were newly identified through screening as part of the study, the results were unexpected. Approximately 42% of chronic HBV and 31% of HCV infections were not known prior to diagnosis through the study. In contrast to the large proportion of previously unidentified hepatitis cases, only two study participants were newly diagnosed with HIV. “I was particularly surprised at the large proportion of people with Hepatitis B who didn’t know they had an active infection,” said Dr. Ramsey.

Overall, the prevalence rates of the hepatitis viruses in the patient population were similar to that of the general U.S. population. The prevalence of previous HBV infection was 6.5% while chronic HBV infection was 0.6%. After adjustment for cancer, age, and race, these rates declined to 5.3% and 0.4%, respectively. The unadjusted HCV prevalence was 2.4% while the adjusted prevalence was 1.9%. The greatest proportion of patients with chronic HBV or HCV was in those with liver cancer as compared to other cancer types. The unadjusted prevalence of HIV was 1.1% and the adjusted rate was 1.0%.

Now that there are better estimates of prevalence of HBV, HCV, and HIV infection in this patient population, the discussion of whether viral testing should be routine in new cancer patients can be better informed. Furthermore, the finding that a substantial proportion of individuals infected with HBV and HCV did not know adds critical new information to the debate. This is important because some cancer drugs may cause severe reactions, including liver failure, in patients with active hepatitis B. The potential impact of screening in cancer patients was emphasized by Dr. Ramsey, “If you’re working toward a cure or long-term remission and miss an opportunity to identify and treat these viruses, it’s a shame to have them diagnosed later in life, where they may manifest as advanced liver disease.” Plans for follow-up studies are under development, “Next steps are creating algorithms to identify patients at highest risk, and also to understand the cost effectiveness of routinely screening for these three viruses in community practice,” said Dr. Ramsey.