Patients with head and neck cancer are now routinely tested for human papillomavirus (HPV), as disease associated with the virus has a different prognosis and different treatment than disease not associated with the virus.
But if the test results are equivocal, the tumor tissue should be tested again using a different test, say researchers reporting a new analysis published online February 13 in The Lancet Oncology.
There are two types of tests for HPV, they explain. The first identifies HPV DNA or RNA within the tumor, whereas the second measures levels of P16, an established protein biomarker assay for HPV. As the P16 test is easier to use, it has been widely adopted as the standard.
However, their analysis shows that it may not be enough.
The team studied the records of more than 7600 oropharyngeal patients who had undergone both p16 and HPV testing and been followed up for more than 5 years.
The results showed that patients with discordant test results were between two and three times more likely to die and approximately twice as likely to experience disease progression than those with positive results on both tests.
Patients with double negative test results were four times more likely to die and over three times more likely to have disease progression than those with two positive results, revealed the research.
“Classification of patients with oropharyngeal cancer based on p16+ immunohistochemistry alone is inadequate in a trial setting,” the authors conclude, “and is likely to be insufficient in routine clinical practice.”
Routine HPV DNA or RNA testing, alongside p16 evaluation, or at least following a positive result on p16 immunohistochemistry, should be mandated in oropharyngeal cancer clinical trials, they suggest.
The authors also say that such double testing is also “recommended in the clinical setting for more accurate counseling on prognosis, and in future circumstances in which treatment de-escalation or intensification are being considered.”
Better Response in HPV+ Disease
Lead author Hisham Mehanna, MB ChB, PhD, said in a release that what is “remarkable” about HPV-related head and neck cancer is that patients “respond much better to current therapies than patients who are not HPV-related.”
“As a result, we are trying to look for less toxic treatments for these patients to reduce the burden of toxicity,” whereas for HPV negative patients “we are doing clinical trials to increase the intensity of treatment, to try to improve outcomes.”
“Therefore, testing for HPV in head and neck cancer patients has become a real priority,” added Mehanna, who is from the Institute of Head and Neck Studies and Education at the Institute of Cancer and Genomics Sciences, University of Birmingham, Birmingham, UK.
“This new research has solved the conundrum puzzling the international community about why some patients respond much better to treatment than others.”
The results also show that patients with discordant tests who were smokers were at higher risk for worse outcomes, as their cancers responded in a similar way to HPV negative tumors, whereas nonsmokers had good outcomes, like HPV positive cancers.
“This has significant implications on how we test head and neck cancer patients moving forward,” Mehanna said, “especially in regions where smoking is still prevalent and HPV disease is not prevalent,” such as in southern and eastern Europe.
“It also has significant implications for how we choose which studies to enroll these patients in, and in future what treatment they get.”
The authors emphasize that HPV-related oropharyngeal cancer, which emerged in around 2000 and has since spread widely, is a distinct disease entity from HPV negative disease, with different epidemiological, molecular, and clinical features.
It also responds better to treatment and has a better prognosis, which prompted the development of separate classifications from HPV-related and HPV-unrelated tumors, as well as several clinical trials assessing treatment de-intensification strategies.
Although p16 is an “excellent surrogate biomarker for HPV” in oropharyngeal cancer, the authors point out that up to 20% of patients with p16-positive tumors test negative for HPV DNA or RNA.
To determine the impact of discordant test results in oropharyngeal cancer, whether p16-/HPV+ or p16+/HPV-, the team conducted a literature search in the PubMed and Cochrane databases for studies of at least 100 patients with primary squamous cell carcinoma of the oropharynx.
The participants were required to have undergone both p16 and HPV testing, and have information available on their age, sex, tobacco and alcohol use, disease staging, treatment received, clinical outcomes, and follow-up.
Thirteen eligible studies were identified, which provided individual data on 13 cohorts of oropharyngeal cancer patients from the UK, Canada, Denmark, France, Germany, the Netherlands, Sweden, Spain, and Switzerland.
Of 7654 patients eligible for inclusion, 74.7% were male, and 25.3 were female. The median patient was 60.0 years. Data on ethnicity was not reported. The majority (76.5%) were current or former smokers.
Among 3805 patients who tested positive on the p16 test, 415 patients (10.9%) were found to be HPV negative. This ranged from 29.6% in Denmark, which had the lowest overall proportion of HPV-related vs unrelated cancers, to 0.5% in Canada (P = .0035).
The remaining 3849 patients tested negative on the p16 test, of whom 289 patients (7.5%) tested positive for HPV. Again, the greatest degree of discordance was seen in Denmark, in 31.1%, while the lowest was in Switzerland, in 1.4%.
The median follow-up period was 5.1 years.
Median overall survival (OS) was 6.9 years, but OS increased to 15.0 years in patients whose tumor tested p16+ and HPV+, and decreased to 3.5 years in p16- and HPV- cases. OS was 5.3 years for p16-/HPV+ patients and 6.7 years for p16+/HPV- patients.
Five-year OS rates were 81.1% for p16+/HPV+ patients, vs 40.4% for p16-/HPV- patients, 53.2% for patients with p16-/HPV+ discordance, and 54.7% for those with p16+/HPV- discordance.
Similarly, 5-year disease-free survival rates were 84.3% for double positive patients, 60.8% for double negative patients, 71.1% for p16-/HPV+ patients, and 67.9% for p16+/HPV- patients.
The team calculates that, compared with p16+/HPV+ patients, the adjusted hazard ratio for death was 2.69 in p16+/HPV- patients, 3.15 in p16-/HPV+ cases, and 4.05 in those with two negative tests.
The adjusted hazard ratio for progression vs p16+/HPV+ patients was 1.92 for p16+/HPV- patients, 2.36 for those with p16-/HPV+ test results, and 3.27 for patients who were negative on both tests.
Although the authors note that the results were similar across European countries, there were too few data from North America to draw any conclusions.
The study was funded by the European Regional Development Fund, Generalitat de Catalunya, National Institute for Health Research (NIHR) UK, Cancer Research UK, Medical Research Council UK, and The Swedish Cancer Foundation and the Stockholm Cancer Society.
Mehanna reports relationships with the UK National Institute of Health research, Cancer Research UK, the UK Medical Research Council, AstraZeneca, MSD, Merck, Nanobiotix, Seagen, Docspert Health. Several co-authors also report numerous relationships with industry. The full list can be found with the original article.
Lancet Oncol. Published online February 13, 2023. Full text
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