Molecular Analysis of HPV 16/18 in Patients with Orophayngeal Squamous Cell Carcinoma from an Inner City Hospital.
Naili Ma, Madhuri Ramanathan, Ada Baisre, Neena Mirani, Ashwinee Ragam, Shivam Naik, Helen Fernandes. UMDNJ, New Jersey Medical School, Newark, NJ
Background: Human papillomavirus (HPV) plays a role in the development of a subset of head and neck cancers such as squamous cell carcinoma (SCC) of oropharynx, particularly tonsillar and base of the tongue with basaloid and non-keratinizing morphology. Molecular evidence shows that 25-30% of tumors are positive for high-risk HPV subtypes, with HPV-16 detected in 95% of cases. Studies have shown that incidence of HPV-associated oral cancers varies with ethnicity. Reports suggest that patients with HPV-positive oral cancers have better prognosis than HPV-negative tumors. We analyzed tumors from patients with oropharyngeal SCC for the presence of HPV subtypes. In addition we studied the status of p16, an important cell cycle regulator in tumors.
Design: Archived formalin fixed paraffin embedded tissue specimens from 100 patients (72 male and 28 female) with oropharyngeal SCC were analyzed. The average age of the patients was 59 years. The study included 41% Caucasian, 24% Hispanic, 20% African-American, and 2% Asian subjects. DNA was extracted from microdissected tumor enriched tissue and real-time amplification was performed on the ABI 7500 with probes specific for HPV 16/18. PCR products were sequenced for confirmation of HPV-16/18. Amplification of the beta-globin gene served as DNA control. Tissue sections were immunostained with a commercially available antibody to p16INK4a.
Results: Real-time PCR assays for the detection of HPV 16/18 were validated using positive cytology specimens, HPV-16 positive SiHa and HPV-18 positive HeLa cell lines. HPV 16 was detected in 27% of patients with oropharyngeal SCC and HPV-18 in 2% of specimens. One specimen was positive for both HPV 16/18. The rates of HPV positivity were comparable for males and females. 39% of the positive specimens belonged to Caucasians and 25% to Hispanics. In contrast HPV 16 was detected in only 5% of specimens from African-American subjects. Immunohistochemistry showed the presence of p16 in 68% of the cases. Most of the specimens (89%) infected with HPV stained positive with the antibody to p16.
Conclusions: Our results show that 27% of oropharyngeal SCC tumors were positive for HPV with HPV 16 being the foremost subtype. HPV positivity was not associated with gender. Caucasians were more likely to have HPV associated with SCC followed by Hispanics. African-American subjects were least likely to have HPV positive oropharyngeal tumors. The p16 expression localizes to HPV-positive cancers. These observations may have important implications for the etiology and follow-up of patients with oropharyngeal cancer.
Category: Head & Neck
Tuesday, March 1, 2011 1:00 PM
Poster Session IV # 146, Tuesday Afternoon