Hepatitis C infection doubles the risk of developing cancers
of the oral cavity, upper throat and larynx, a meta-analysis of eight studies
has shown and the study authors say that people with hepatitis C should be
checked regularly for these cancers.
The findings are published in the journal Oral Oncology.
Hepatitis C is linked to the development of several types of
cancer apart from hepatocellular carcinoma (liver cancer), including non-Hodgkin
lymphoma. Some studies have shown that people with hepatitis C are at higher
risk of developing several types of head and neck cancers, but these studies
have been small and estimates of the increased risk vary.
type of tumour affecting the lymph nodes.
Head and neck cancers are defined as those occurring in the oral
cavity, the nose and sinuses, the salivary glands, the back of the nose and
throat (nasopharynx), the upper throat (oropharynx), the lower throat
(hypopharynx) or the voice-box (larynx). These cancers are most often caused by
smoking and alcohol. Oropharyngeal cancer is often caused by human
Almost all head and neck cancers start in the squamous cells
that line the mouth, throat and nose. Cancers of the mouth are the most common
head and neck cancers. Approximately 12,000 head and neck cancer were diagnosed
in the United Kingdom between 2015 and 2017 and head and neck cancers cause
450,000 deaths worldwide each year.
risk of developing a head or neck cancer is relatively low, although the
incidence of these cancers is on the rise. Men are about twice as likely as
women to develop one of these cancers. The lifetime chance of developing oral
cancer is around one in fifty for men born after 1960 in the United Kingdom, Cancer Research UK has calculated. The risk of other head and neck
cancers is lower. Head and neck cancers are more common in Asia.
Investigators from the United Kingdom, Italy and United States
carried out a meta-analysis of published studies of head and neck cancer risk
in people with hepatitis C.
They identified eight studies (3 case control and 5
observational studies) that reported on the risk of head and neck cancers in
people with confirmed hepatitis C infection.
The case control studies matched 1625 cases of head and neck
cancers with 2561 controls. Observational cohort studies (three in people with
viral hepatitis) reported 58 cases.
Seven studies reported on the association between hepatitis
C and oral cancers, finding that people with hepatitis C were approximately twice
as likely as others to develop oral cancer (pooled relative risk 2.13, 95% CI
Five studies reported on the risk of oropharyngeal cancer, finding
that people with hepatitis C were approximately twice as likely as others to
develop oropharyngeal cancer (RR 1.81, 1.21-272).
Three studies reported on the risk of laryngeal cancer,
showing that people with hepatitis C were approximately two-and-a-half times more
likely than others to develop laryngeal cancer (RR 2.51, 1.11-5.94).
Only two studies reported on the risk of hypopharyngeal
cancers and this did not show an increased risk in people with hepatitis C.
The association between hepatitis C and head and neck
cancers persisted after people with HIV co-infection were excluded from the analysis
(immunosuppression caused by HIV raises the risk of some cancers).
The authors say that the mechanism through which hepatitis C
might influence cancer development is unknown, although the virus can be isolated
from saliva and has been found in cancer epithelial cells in people with oral
cancer. But the authors also acknowledge that studies included in this analysis
did not carry out sub-group analyses which took into account smoking, alcohol
consumption or human papillomavirus infection, each of which might be more
prevalent in people with hepatitis C.
Doctors treating people with head and neck cancers should
consider the possibility of undiagnosed hepatitis C and liver specialists
should carry out regular checks for head and neck cancers in their patients
with hepatitis C, the authors conclude.