683 - Pathologic Staging Changes in Oral Cavity Squamous Cell Carcinoma—Stage Migration and Implications for Adjuvant Treatment

Background

The American Joint Committee on Cancer 8^th Edition (AJCC 8) for oral cavity squamous cell carcinoma (OCSCC) incorporates depth of invasion (DOI) into the pathologic tumor classification (pT) and pathologic extranodal extension (pENE) into the pathologic nodal classification (pN). We sought to evaluate the incidence and prognostic importance of stage migration as a result of these changes on the AJCC 8 staging system.

Methods

From the National Cancer Database, cohorts were identified from patients with OCSCC undergoing definitive surgery between 2004-2013 for pT (n = 7,184), pN (n = 13,627), and pathologic Stage (pStage; n = 5,580) analysis.

Results

DOI and pENE were prognostic in all groups except AJCC 7 pN3. Upstaging was seen in 12.4% of patients for pT classification, 13.3% for pN classification, and 24.8% for overall pathologic stage grouping. Notably, upstaging led to similar or improved five-year overall survival (5-YR OS) for every AJCC 8 pT/N classification except pStage IVB. AJCC 7 pT1 tumors upstaged to AJCC 8 pT3 tumors had improved overall survival compared to the remainder of the pT3 group (71.7% vs 43.7%, respectively, P < 0.0001). A multivariable analysis of up-staged pT3N0 patients demonstrated a reduced risk of death with receipt of PORT (HR 0.56, 95% CI 0.33-0.95, P = 0.03).

Conclusions

Upstaging is common in AJCC 8, and upstaged tumors demonstrate improved survival; these factors that should be kept in mind when interpreting data using the new staging system. Postoperative radiotherapy may reduce death in newly upstaged pT3N0 patients, and further study is needed in this area.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Yale School of Medicine.

Funding

Research reported in this publication was supported by the National Institute on Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number T35DK104689 (NCJL). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This publication was made possible by the Yale School of Medicine Medical Student Fellowship (NCJL).

Disclosure

B. Burtness: Honoraria (self), Research grant / Funding (institution): Advaxis; Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Bristol-Myers Squibb; Honoraria (self): IDDI; Advisory / Consultancy: AstraZeneca; Advisory / Consultancy, Travel / Accommodation / Expenses: Boehringer Ingelheim; Advisory / Consultancy: Celgene; Advisory / Consultancy: Genentech. All other authors have declared no conflicts of interest.