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Program Number: B337
Session Name: Poster Session

Adjuvant Chemotherapy Does Not Improve Overall Survival in Positive Surgical Margin Oral Cavity Cancer Patients Without Extranodal Extension

Daniel R Habib, BA¹; Yike Li, MD, PhD²; Patrick Tassone, MD, MS³; Ramez H Philips, MD⁴; Pratyusha Yalamanchi, MD, MBA⁵; F. Christopher Holsinger, MD⁶; Michael C Topf, MD, MSCI²; ¹Vanderbilt University School of Medicine; ²Vanderbilt University Medical Center; ³University of Missouri Health Care; ⁴University of Chicago Medicine; ⁵Michigan Medicine; ⁶Stanford Medicine

Objectives: National Cancer Comprehensive Network Guidelines recommend adjuvant chemoradiotherapy (CRT) for oral cavity squamous cell carcinoma (OCSCC) patients with positive margins and/or extranodal extension (ENE) based on data from two landmark clinical trials: EORTC 229311 and RTOG 95-01. However, in both trials, only a small minority of patients had positive margins without ENE. The objective of this study is to determine whether CRT is associated with an overall survival (OS) difference compared to radiotherapy (RT) alone in patients with stage III-IV OCSCC with positive margins without ENE. 

Study design: Retrospective cohort study using the National Cancer Database (NCDB). 

Methods: This NCDB study included adult cM0 stage III-IV oral cavity cancer patients who underwent curative-intent resection of OCSCC with final positive margins between 2018 and 2021 across over 1,400 U.S. hospitals. All patients received adjuvant RT. Exclusion criteria included lymph node yield of less than five, prior RT, and neoadjuvant chemotherapy. A 1:1 propensity match in patients with positive margins without ENE as well as a 3:1 propensity match in patients with positive margins with ENE adjusting for age, Charlson-Deyo Comorbidity Index, pathologic T and N stage, and lymphovascular invasion (LVI) were performed for patients undergoing surgery and adjuvant RT for OCSCC with and without adjuvant chemotherapy. In addition to Kaplan-Meier survival analysis, Cox proportional hazard analysis was used to calculate hazard ratios (HRs) for OS in the matched cohorts by adjuvant chemotherapy while controlling for significant propensity-matched variables.

Results: After exclusion, the total cohort included 689 cases, of which 487 (70.7%) received adjuvant chemoradiation, and 202 (29.3%) received adjuvant RT alone. In the propensity-matched cohort of 189 patients with positive margins without ENE, there was no OS benefit on Kaplan-Meier survival analysis for adjuvant CRT compared to adjuvant RT alone (Figure 1; p=.844). There was a trend toward adjuvant CRT improving survival in the propensity-matched cohort of 228 patients with positive margins without ENE (p=.137). On Cox proportional hazard analysis, adjuvant CRT was not associated with OS in patients with positive margins without ENE (HR=1.00, 95% CI: 0.63-1.56, p=.988) after controlling for propensity-matched variables.

Conclusion: In this NCDB study, adjuvant CRT for OCSCC patients with positive margins without ENE was not associated with improved OS compared to adjuvant RT alone.

 

Figure 1. Kaplan Meier Survival Analysis by Adjuvant Chemotherapy in Patients with Positive Margins without Extranodal Extension

 

 

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