Patterns of Care and Outcomes in Patients with Squamous Cell Carcinoma of the Buccal Mucosa

Abstract

Primary buccal mucosa squamous cell carcinoma represents approximately 2% of all oral cavity cancer cases in the United States annually. Resection, followed by adjuvant therapy if indicated, is the preferred management, with definitive radiation or chemoradiation reserved for situations where surgery isn’t feasible. The purpose of this study was to examine patterns of care and outcomes for squamous cell carcinoma of the buccal mucosa. Using the National Cancer Data Base (NCDB) we identified 5,786 patients with primary buccal mucosa squamous cell carcinoma diagnosed between 2004-2014. Patients who lived less than 3 months from diagnosis or who had stage 0 or IVC disease were excluded. Patient and treatment factors were compared between patients who received surgery alone (S), postoperative radiation therapy (S+RT), postoperative chemoradiation (S+CRT) or definitive chemoradiation (CRT) using the Chi-square test. Univariate and multivariate Cox proportional hazards regression models were used for covariate survival analysis. The final cohort analysis included 2,570 patients. Median age and median follow-up for the cohort were 69 years and 44 months, respectively. 1068 patients had stage I/II disease and 936 had stage III-IVB. 1,468 (57.1%) patients received surgery alone, 605 (23.5%) received S+RT, 300 (11.7%) S+CRT, and 197 (7.7%) definitive CRT. Median total radiation dose was 64 Gy (IQR 60 – 70) for those that received RT. The 3-year overall survival of the entire cohort was 71.8%, 58.4%, 52.6%, and 35.8% for the S, S+RT, S+CRT, and CRT arms, respectively. The 3-year survival by stage were 71.3% (I-II), 54.5% (III) and 38.7% (IVA-IVB). Charlson/Deyo score of 32 (HR 1.65, 95% CI 1.16-2.30, p<0.001), overall stage III-IVB disease (HR 1.85, 95% CI 1.48-2.30, p<0.001), presence of ECE (HR 1.43, 95% CI 1.12-1.83, p=0.004) were associated with worse survival on multivariate analysis. Higher number of neck nodes removed were associated with improved survival (HR 0.65-0.69, p<0.05). Nearly 60% of buccal mucosal cancers present with stage III-IVB disease. Consistent with national guidelines, more than 90% of patients were treated with surgery with or without adjuvant therapy rather than definitive chemoradiation. Patients presenting with stage IVA-IVB disease have a very poor prognosis, with a 3 year overall survival of 38%.