Outcomes Are Better for HPV16-Associated Oropharyngeal Cancer, but Not for Other HPV Strains
Patients with oropharyngeal tumors that harbor human papillomavirus type 16 (HPV16) have higher 5-year survival and lower recurrence rates than patients with tumors that harbor other HPV strains or are HPV-negative, a study published in the journal Oral Oncology has shown.1
Previous studies showed that patients with HPV-associated oropharyngeal tumors have better response to treatment compared with patients whose oropharyngeal tumors are HPV-negative. Therefore, researchers sought to determine if less intensive treatment would result in good outcomes in this patient population, thereby sparing these patients the negative side effects of medications or radiation therapy.
For this study, researchers at University of North Carolina (UNC) Lineberger Comprehensive Cancer Center analyzed survival data for 238 patients in North Carolina with oropharyngeal cancer diagnosed between January 2002 and February 2006 as part of the Carolina Head and Neck Cancer Study (CHANCE).
The analysis revealed the 5-year survival for patients with HPV16-associated oropharyngeal cancer was 71.4%, but only 57% for patients whose tumors harbored other HPV strains. Five-year survival was even lower (50%) for patients whose tumors were HPV-negative.
These results demonstrate that patients with tumors positive for HPV strains other than HPV16, as well as patients with HPV-negative tumors, may not be good candidates for treatment de-intensification, concluded the researchers.
However, additional research utilizing a larger sample size is needed to rule out other reasons for the differences in survival rates, and to clarify whether findings of other HPV strains were not false-positives.
An additional finding from this study was that a commonly used clinical test to determine the presence of the p16 protein may not be specific enough to identify those patients with HPV-associated oropharyngeal cancer who are good candidates for less intensive treatment.
Comparing the results of the p16 test with those of a more specific genetic test, the researchers found that 4.3% of patients were positive for p16, but genetic test results showed these patients were negative for HPV. In another approximately 11% of cases of p16-positive tumors, genetic test results showed these tumors were positive for other HPV strains.
Many clinical trials utilizing de-intensified treatment use p16 expression alone to determine the HPV status of a patient's cancer and whether the patient should be considered for treatment de-intensification.
"Even though we rely almost exclusively around the country on p16 positivity as a surrogate for HPV16 presence, this sheds some light on the fact that maybe we should be considering HPV genotyping because of the survival differences we saw here," said Jose P. Zevallos, MD, MPH, an associate member of UNC Lineberger and an associate professor in the UNC School of Medicine, and senior author of the study.2
1. Mazul AL, Rodriguez-Ormaza N, Taylor JM, et al. Prognostic significance of non-HPV16 genotypes in oropharyngeal squamous cell carcinoma. Oral Oncol. 2016;61:98-103.
2. UNC Lineberger Comprehensive Cancer Center. Particular HPV strain linked to improved prognosis for throat cancer. EurekAlert! web site. https://www.eurekalert.org/pub_releases/2016-10/ulcc-phs100316.php. Accessed October 3, 2016.