Pancreatic cancer occurred more often in people with hepatitis C or HIV in Canada’s British Columbia Hepatitis Testers Cohort, and colorectal cancer was more likely to occur in people diagnosed with hepatitis B or C, or HIV, cohort investigators report in the journal Therapeutic Advances in Medical Oncology.
The study also found an increased risk of liver cancer in people diagnosed with viral hepatitis, including those living with HIV.
People with hepatitis B or C are at higher risk of developing liver cancer and there is some evidence that viral hepatitis raises the risk of developing several other cancers, including colorectal cancer. HIV infection is also associated with an increased risk of some cancers, but it is unclear whether co-infection with HIV and hepatitis B or C increases the risk of developing cancers.
The British Columbia Hepatitis Testers Cohort records data on almost everyone tested for hepatitis or HIV in the Canadian province of British Columbia since 1990. Test results can be linked with the provincial cancer registry, allowing investigators to assess the incidence of cancers in people diagnosed with hepatitis B and C or HIV, and compare them to people with similar risk factors for these infections who tested negative for the viruses.
Between 1990 and 2016, 658,697 people were tested in the province for all three infections; 5.3% tested positive for hepatitis C virus (HCV) antibodies, 2.6% positive for hepatitis B virus (HBV) and 0.7% positive for HIV. Of the overall cohort, 0.5% had co-infection with HCV and HBV, 0.4% had both HIV and HCV and 0.1% had HIV and HBV. Testers were followed for a median of eleven years after testing.
During the study period, 489 people (0.07%) were diagnosed with pancreatic cancer. People with HIV and people with HCV were each at 2.8 times higher risk of developing pancreatic cancer compared to people who tested negative for these viruses, while people with HBV/HCV co-infection were at 2.9 times higher risk of developing pancreatic cancer.
During the study period, 1407 people (0.21%) were diagnosed with colorectal (bowel) cancer. People with viral hepatitis or HIV were between 2.3 and three times more likely to be diagnosed with colorectal cancer, and people with HIV and HCV co-infection were 2.38 times more likely to be diagnosed with colorectal cancer, compared to uninfected people.
A total of 1294 people (0.21%) were diagnosed with liver cancer. Any viral hepatitis infection greatly increased the risk of liver cancer. People with hepatitis B were at 85 times higher risk of developing liver cancer, people with hepatitis C at 121 times higher risk and people co-infected with hepatitis B and C at 106 times higher risk. People with HIV did not have a raised risk of liver cancer unless they were co-infected with hepatitis B or C. The higher risk of liver cancer in people diagnosed with hepatitis C was reduced, but not eliminated, in those cured of hepatitis C.
Although some previous studies have found a higher risk of pancreatic cancer in people with hepatitis C and people with HIV, this is the largest population study to find an association. The investigators say that the association persisted after controlling for diabetes, which may be a complication of hepatitis C or antiretroviral treatment for HIV.
The underlying mechanisms that lead to a higher risk of colorectal and pancreatic cancer in these groups are unclear, say the investigators, but their findings “highlight the need for cancer prevention and diligent clinical monitoring”, they conclude. They point out that even though liver screening is recommended for people with hepatitis B every six months in the United States and Canada, few people receive regular ultrasound screening.