Patients infected with HCV may be at higher risk for developing certain head and neck cancers.
Study co-author Dr. Harrys A. Torres, of the Department of Infectious Diseases, Infection Control and Employee Health at the University of Texas MD Anderson Cancer Center, and colleagues publish their findings in the Journal of the National Cancer Institute.
Hepatitis C is the most common blood-borne infection in the US; almost 30,000 Americans have acute hepatitis C virus (HCV) infection, while around 3.5 million Americans have chronic HCV infection.
According to the Centers for Disease Control and Prevention (CDC), around 75-85% of people infected with HCV will go on to develop chronic infection, of whom around 60-70% will develop chronic liver disease.
Over a 20-30-year period, it is estimated that around 5-20% of people with chronic HCV infection will develop cirrhosis, while around 1-5% will die from cirrhosis or liver cancer. Chronic HCV infection has also been linked to increased risk of the blood cancer non-Hodgkin's lymphoma.
Now, for the first time, Dr. Torres and colleagues have identified a link between HCV and head and neck cancers - a finding they say could have important implications for the screening of HCV and the treatment of such cancers.
Assessing the link between HCV and head and neck cancers
To reach their findings, the team identified 34,545 patients who were tested for HCV at the MD Anderson Cancer Center between 2004-2014.
- Around 70-80% of people with acute HCV do not have any symptoms
- If symptoms do occur, they arise around 6-7 weeks after exposure to the virus
- Symptoms include fever, fatigue, nausea, vomiting, loss of appetite, abdominal pain and dark urine.
Of these patients, 409 had head and neck cancers, of whom 164 had oropharyngeal cancers and 245 had non-oropharyngeal cancers.
Oropharyngeal cancers are cancers that begin in the oropharynx - the middle section of the throat - including the back one third of the tongue, soft palate, the side and back walls of the throat and the tonsils.
Non-oropharyngeal cancers are cancers that begin in the mouth, including the front two thirds of the tongue, the hard palate (roof of the mouth), the floor of the mouth under the tongue, the larynx, the gums and lips.
The researchers note that it was important to account for smoking in this study, as it is a key risk factor for head and neck cancers. As such, they pinpointed 694 control patients who had been diagnosed with a smoking-related cancer, including lung, bladder and esophageal cancers.
All patients included in the study underwent testing for HCV antibodies, and - where possible - patients had viral RNA tests, which were used to confirm the presence of chronic HCV infection.
Up to five times greater risk for certain head, neck cancers with HCV
The researchers found that 20% of patients with non-oropharyngeal cancers and 14% of patients with oropharyngeal cancers tested positive for HCV antibodies, compared with only 6.5% of patients in the control group.
Assessing the risk for specific head and neck cancers, the researchers found that patients with HCV infection were at 2.4 times increased risk for oral cavity cancers, 2.04 times greater risk for oropharynx cancers and 4.96 times increased risk for larynx cancers.
"Our findings tell us that the association between hepatitis C and oropharyngeal and non-oropharyngeal cancers is as high as its link to non-Hodgkin's lymphoma," notes Dr. Torres; previous studies have shown that patients infected with HCV may be two to three times more likely to develop non-Hodgkin's lymphoma.
The team notes that 145 of the patients with oropharyngeal cancers were also tested for human papillomavirus (HPV) in order to determine whether there is a link between HPV, HCV and head and neck cancers.
The researchers found that patients with oropharyngeal cancers who tested positive for HCV were also more likely to test positive for HPV - a finding that Dr. Torres says should be investigated in future studies.
Important implications for HCV screening and treatment
While the researchers' results may be a concern for patients with HCV, they note that in recent years, new antiviral drugs have emerged, which have been found to cure more than 90% of patients with the virus.
As such, the team says the findings highlight the importance of screening for HCV, noting that diagnosing and treating the condition with antiviral drugs could prevent head and neck cancers from developing.
The results may also have important implications for patients who have already been diagnosed with head and neck cancers.
The team explains that the National Comprehensive Cancer Network guidelines suggest that HCV should be treated first among non-Hodgkin's lymphoma patients with the virus, given that HCV can be cured. Could the same strategy work for HCV-infected patients with head and neck cancers?
This is the question the team wants to find the answer to. The researchers now plan to screen and treat all HCV-infected head and neck cancer patients at MD Anderson and monitor their outcomes.
"What we are trying to make all understand is that this is an infection that has consequences - and it's an infection we can cure," says Dr. Torres.
Last month, Medical News Today reported on a review from the World Health Organization (WHO) that found HIV (human immunodeficiency virus) and HCV co-infect more than 2 million people across the globe.