Abstract
Factors influencing the prognosis of patients with p16-positive oropharyngeal carcinoma in whom surgery is selected as the initial treatment have not yet been determined. We retrospectively reviewed the data of 55 cases of p16-positive oropharyngeal carcinoma who underwent surgery as the initial treatment at the Department of Otolaryngology, Head and Neck Surgery, University of Tokyo, between 2004 and 2019. The variables examined were the old and new staging, resection margin status, number of metastatic lymph nodes, presence/absence of extranodal extension, and use of postoperative irradiation (yes/no), and the results were compared by univariate analysis. The patients ranged in age from 46 to 82 years (median 67 years), and the male/female ratio was 47/8. Stage I/II/III/IV cases were 3/10/13/29 cases according to the old classification, and Stage I/II/III cases were 47/6/2 cases according to the new classification. The transoral approach/open approach was used in 40/15 cases, of which 15cases (11 transoral/4 open) had positive surgical margins, 6 cases of p16-positive oropharyngeal carcinoma who underwent surgery as the initial treatment had 5 or more lymph node metastases, and 7 cases of p16-positive oropharyngeal carcinoma who underwent surgery as the initial treatment had extranodal extension. Univariate analysis identified pN0 as a favorable prognostic factor, and a trend towards a better prognosis in patients who received postoperative adjuvant radiotherapy, although the difference did not reach statistical significance. The overall 5-year overall survival rate and 5-year recurrence-free survival rate were 86.2% and 75.2%, respectively. The 5-year overall survival rate and 5-year recurrence-free survival rate were influenced by the 8th edition stage classification and the number of pathologically positive lymph nodes (pN classification). In conclusion, in this single-center retrospective study, the number of pathologically positive lymph nodes correctly predicted the prognosis in patients with p16-positive oropharyngeal carcinoma who underwent surgery as the initial treatment, suggesting the possibility of prognostic stratification by PN classification.
