Among patients with oropharyngeal cancer, the presence of a high-risk type of human papillomavirus, coupled with high levels of a protein known as p16, may identify a subset of patients with a good prognosis. These results were published in the Journal of Clinical Oncology.
Approximately 40,000 people in the U.S. are diagnosed with head and neck cancer every year. Cancers of the head and neck include cancers of the nasal cavity and sinuses, oral cavity, nasopharynx, and oropharynx.
Factors that increase the risk of head and neck cancers include tobacco, alcohol use, and possibly infection with high-risk types of human papillomavirus (HPV). HPV16 is a type of HPV that has been linked with cervical cancer, and evidence of HPV16 has been found in tumor samples from some patients with head and neck cancer as well. Some studies have suggested that HPV-linked head and neck cancers have a better prognosis than head and neck cancers that do not show evidence of HPV.
To further explore the role of HPV in oropharyngeal cancer, researchers conducted a study among 78 patients. In addition to simply determining whether HPV16 was present or absent, the researchers also collected information about levels of a protein known as p16. High levels of p16 have been reported in cancers caused by HPV. Information about p16 level may provide clues about whether or not HPV played a role in causing the cancer. If HPV is present but p16 levels are low, factors other than HPV may have caused the cancer.
The researchers divided subjects into three groups based on the presence of HPV16 and p16 in tumor tissue:
- Class 1: HPV16 negative, p16 low (39% of subjects)
- Class 2: HPV16-positive, p16 low (37% of subjects)
- Class 3: HPV16-positive, p16 high (23% of subjects)
One subject had a tumor that was HPV16-negative, p16 high. Because this combination was so rare, this subject was excluded from the analysis.
Outcomes were best for patients in class 3 (HPV16-positive, p16 high):
- Overall survival was 20% for patients in class 1, 18% for patients in class 2, and 79% for patients in class 3.
- The probability of local cancer recurrence within five years was 45% for patients in class 1, 74% for patients in class 2, and 14% for patients in class 3.
The researchers conclude that oropharyngeal tumors that are HPV16-positive and have high p16 levels have a better prognosis than other oropharyngeal tumors.
Reference: Weinberger PM, Yu Z, Haffty BG et al. Molecular Classification Identified a Subset of Human Papillomavirus-Associated Oropharyngeal Cancers with Favorable Prognosis. Journal of Clinical Oncology. 2006;24:736-747.