Protein Test Improves Survival Prediction for Oropharyngeal Carcinoma

A simple protein test could prove more useful in predicting survival chances for patients with head-and-neck cancer compared to existing methods.

There is an increasing incidence of human papillomavirus (HPV)-positive oropharyngeal squamous cell cancers (OPSCC) mostly associated with favorable outcomes and a tumor suppressor protein could be a surrogate marker for HPV positivity in OPSCC.

Scientists at the University of Manchester (UK) collected formalin-fixed, paraffin-embedded blocks from hospitals where 217 patients were being treated for OPSCC. One approach for detecting HPV-associated oral cancer relies on finding HPV DNA in the tumor sample, but these DNA-based tests may not accurately classify the tumor. Another approach is to use a marker of HPV rather than testing for HPV DNA directly. The p16 protein usually disappears in tumors that are not caused by HPV infection and has been proposed as a surrogate marker of HPV.

Blocks with confirmed tumor presence were selected for immunohistochemistry (IHC), which was carried out using the CINtec histology kit (MTM Laboratories, Heidelberg, Germany). Stained slides were scanned using the Leica SCN 400 (Wetzlar, Germany). The cyclin-dependent kinase inhibitor protein p16 expression was scored as positive if there was a strong and diffuse brown staining of the nucleus and cytoplasm in equal to or greater than 70% of the tumor specimen. Of the 92% of the OPSCC originating from tonsil and tongue base sites, 61% were p16 positive. The study showed that p16 is the single most important prognostic variable in OPSCC, surpassing traditional prognostic factors for both cancer-specific survival (CSS) and recurrence-free survival (RFS). Furthermore, disease stage has no prognostic significance in p16-positive patients, highlighting the need for routine p16 assessment in OPSCC.

Catharine M.L. West, PhD, the lead author of the study said, “Despite presenting with a more advanced stage of cancer, patients whose tumors tested positive for p16 had greater survival when compared with p16-negative patients. Applying this test in the clinic could help guide treatment decisions and potentially allow doctors to choose more appropriate and tailored treatments. Many studies have now shown p16 status is strongly linked to survival. Now we have shown the test works better than routine staging for some cancers, we would recommend this test be offered as standard.” The study was published in the November 2013 issue of the journal Clinical Oncology.

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