Patients with p16-positive non-oropharyngeal squamous cell carcinoma experienced better outcomes than those with p16-negative tumors, according to an analysis of three prospective clinical trials.
Previous studies showed p16 protein expression — a surrogate marker for oncogenic HPV infection — is a prognostic marker in oropharyngeal squamous cell carcinoma (OPSCC). However, the prevalence and significance of p16 protein expression in non-OPSCC — which includes cancers of the larynx, hypopharynx and oral cavity — has not been established, according to background information provided by researchers.
In the current study, researchers tested tumors of 356 patients with non-OSCC tumors who were enrolled in the RTOG 0129, 0234 and 0522 studies. They determined p16 expression for 322 (90.4%) of those tumors.
Overall, 62 of the 322 tumors (19.3%) with confirmed p16 status tested positive. The highest rates of p16 positivity were observed in cancers of the oral cavity (26.3%), followed by cancers of the larynx (17.1%) and hypopharynx (16.4%).
Researchers determined patients with p16-positive tumors experienced significantly longer PFS (HR=0.63; 95% CI, 0.42-0.95) and OS (HR=0.56; 95% CI, 0.35-0.89) than those with p16-negative tumors.
Results also showed patients with p16-positive OPSCC demonstrated superior PFS and OS compared with those who had p16-positive non-OPSCC. However, outcomes among those with p16-negative OPSCC and p16-negative non-OPSCC were similar, according to researchers.
“Similar to results in patients with OPSCC, patients with p16-negative non-OPSCC have worse outcomes than patients with p16-positive non-OPSCC, and HPV may also have a role in outcome in a subset of non-OPSCC,” the researchers concluded. “However, further development of a p16 immunohistochemistry scoring system in non-OPSCC and improvement of HPV detection methods are warranted before broad application in the clinical setting.”
Disclosure: The researchers report honoraria from Bristol-Myers Squibb and Merck, as well as other remuneration from Roche.