The study found that 14 per cent of patients with oropharyngeal cancers tested positive for hepatitis C virus antibodies. (Representational Image)
People infected with the hepatitis C virus (HCV) are two to five times more likely to develop certain head and neck cancers, a new study has warned.
The findings could have significant implications for both the screening of those with the virus and the treatment of those with head and neck cancers, researchers said.
In the last few years, new antiviral drugs have made it possible to cure more than 90 per cent of the HCV population.
The antivirals are oral medications taken once or twice daily with almost no side effects, they said.
"Now that many with hepatitis C can be cured, it is important that we first address and potentially cure the virus, so that they can have access to necessary cancer therapy," said Harrys A Torres from University of Texas in the US.
"To our surprise, we saw a number of head and neck cancer patients who tested positive for the hepatitis C virus. With this observation we began to wonder if there was an undiscovered correlation between the two," said Mr Torres.
"Our findings tell us that the association between hepatitis C and oropharyngeal and nonoropharyngeal cancers is as high as its link to non-Hodgkin's lymphoma," he added.
Oropharyngeal cancers occur in the oropharynx, or the middle part of the throat, including the back one-third of the tongue, the soft palate, tonsil, and side and back walls of the throat.
Nonoropharyngeal cancers include those occurring in the oral cavity, nasal cavity and larynx.
For the study, researchers identified 34,545 patients who were tested for HCV between 2004 and 2014. All patients were tested for HCV antibodies and viral RNA tests were used to confirm chronic infection, when available.
Researchers included 409 head and neck cancer patients as case subjects (164 with oropharyngeal and 245 with nonoropharyngeal).
Also paramount to the research, said Mr Torres, was to control for smoking, a major risk factor for head and neck cancers. Therefore, they identified 694 control subjects, all with a diagnosis of smoking-related cancers (378 with lung, 168 with esophageal and 148 with bladder).
The study found that 14 per cent of patients with oropharyngeal cancers tested positive for HCV antibodies, compared to just 6.5 per cent in the control group. In those with nonoropharyngeal cancer, 20 per cent tested positive for HCV antibodies.
Compared to the controls, researchers found that the risk for HCV patients of developing specific head and neck cancers was increased 2.4 times for oral cavity cancers, 2.04 times for oropharynx cancers, and 4.96 times for larynx cancers.
As many as 145 of all the oropharyngeal cancer patients were also tested for human papillomavirus (HPV), allowing researchers to compare possible associations between the two viruses. Patients with HCV-positive head and neck cancers were more likely to also test positive for HPV.
The findings were published in the Journal of the National Cancer Institute.