We retrospectively examined 181 pT4 OSCC patients who had radical resections between 2003 and 2010. The 5-year control and survival rates were the main outcome measures.
Of the 181 resected pT4 OSCC patients, 133 (73 % ) had pT4a disease, and 48 (27 % ) had pT4b disease. All of the resected T4b tumors were below the mandibular notch (infra-notch pT4b). The 5-year outcomes of the patients with infra-notch pT4b and pT4a were comparable: local control, 80 % vs. 78 % , p = 0.7275; neck control, 87 % vs. 82 % , p = 0.4798; distant metastases, 22 % vs. 23 % , p = 0.8871; disease-free survival, 63 % vs. 55 % , p = 0.2813; disease-specific survival, 68 % vs. 60 % , p = 0.3526; and overall survival, 62 % vs. 44 % , p = 0.2643, respectively. Extracapsular spread was the only independent prognostic factor for 5-year survival rates in pT4a patients. Poor tumor differentiation and pN2 status were the independent 5-year survival prognostic factors for the infra-notch pT4b tumor patients.
Infra-notch pT4b had outcomes comparable with those of pT4a tumors, although they displayed different risk factors. We therefore recommend that resectable infra-notch pT4b tumors should be classified as pT4a disease in the AJCC tumor staging.