New standard for HPV testing could improve diagnosis of head and neck cancers

Head and neck squamous cell carcinoma is the sixth commonest cancer worldwide, accounting for approximately one in 25 tumours. Among the most common types of this particular cancer is oropharyngeal squamous cell carcinoma (OPSCC), which can be caused by a number of agents including the human papillomavirus type 16 (HPV16) as well as excessive smoking or drinking.

Where these tumours are caused by HPV16, prognosis has been shown to be significantly better - but diagnosis is not always accurate. Attention on HPV, particularly in the last several years, has led to a number of diagnostic tests being developed, but the evaluation of these tests has lagged behind, despite their known limitations.

Now, in a paper published in the journal 'Clinical Cancer Research', researchers at the University of Liverpool and Newcastle University have demonstrated the most accurate test for diagnosing head and neck cancers caused by HPV.

For the study, the researchers evaluated eight possible combinations of known diagnostic tests on 108 cases of HPV16-derived OPSCC. They used viral gene expression as the standard marker, a test that is 100 per cent accurate, but requires very-high-quality tissue that is often not available.

After evaluating the tests, they found that a combination of quantitative PCR (used to determine levels of viral DNA) and testing for the gene p16 gene had 97 per cent sensitivity, a measure of accurate positive tests, and 94 per cent specificity, a measure of accurate negative tests. Both of these assays are commercially available in patented and generic forms, so the combination test could be administered.

"Getting the diagnosis right is extremely important because cases caused by the HPV16 virus may, in the near future, receive less aggressive therapy," said lead researcher Andrew Schache from the University of Liverpool, who was last year awarded the first joint training research fellowship from the Wellcome Trust and the Royal College of Surgeons. "But of course, you do not want to withhold treatment from a more aggressive case."

The study also showed that the proportion of OPSCC caused by HPV in the UK has more than trebled over the past two decades, from 14 per cent of cases to 57 per cent, reflecting similar trends in other high-income countries. The reason for this is unclear, but it may reflect the reduction in the number of cases caused by excessive smoking or drinking.

According to Schache, the data will be of interest to policy makers deciding whether to vaccinate young males against HPV in addition to females. Timely decisions may be needed as the majority of cases of OPSCC do not occur until middle age, and any benefits from vaccinating young males prior to their first sexual contact may take 30 years to realise.