BOSTON – Decreased expression of the PTPN13 gene is associated with improved survival of patients with head and neck squamous cell carcinoma positive for the human papillomavirus, a small retrospective study suggests.
Dr. George F. Harris IV of the University of Iowa, Iowa City, and his colleagues examined the correlation of human papillomavirus (HPV) status; protein tyrosine phosphatase, nonreceptor type 13 (PTPN13) status, and survival over 10 years in 21 patients for whom tissues samples were available for analysis. The patients, identified from University of Iowa Health Care (UIHC) Oncology Registry, were diagnosed with oropharyngeal head and neck squamous cell carcinoma (HNSCC) in 1995.
All 21 patients had HPV-positive cancer – 9 with decreased PTPN13 expression and 12 with unchanged or increased expression of PTPN13. Average survival was approximately 105 months in the low-PTPN13 group vs. 61 months in patients with unchanged or increased PTPN13 expression, Dr. Harris reported at the annual meeting of the American Academy of Otolaryngology–Head and Neck Surgery.
"An average increase in survival of about 30 months was seen for those patients who had decreased expression of PTPN13 within the tumor," he stated.
Looking at demographics, the investigators found that patients in the "decrease" group were younger at diagnosis but had more advanced disease. Observed Dr. Harris, "These may be confounding variables, but the finding is consistent with other authors' experience with HPV-associated H&N cancer in general."
The investigators employed real-time polymerase chain reaction (RT-PCR) to detect HPV type and activity. Dr. Harris said they used immunohistochemistry to evaluate the status of PTPN13, which has been shown to have a physiologically significant role in regulating mitogen-activated protein (MAP) kinase signaling. The identification and activity of HPV was confirmed by increased p16 immunochemical staining – an accepted marker for HPV activity because, in oropharyngeal HNSCC, HPV integration induces an overexpression of P16, he noted.
The improved survival observed among HPV positive HNSCC patients with decreased PTPN13 expression may be related to the fact that PTPN13 degradation is associated with fewer genetic changes than stable or elevated PTPN13 expression, according to Dr. Harris. It is possible that analyzing PTPN13 status in HPV-positive HNSCC "may identify those patients that will have better survival or, conversely, those patients who may require additional treatment," he said.
Dr. Harris reported having no conflicts of interest with respect to this presentation.