Postoperative radiotherapy is associated with improved survival in pT1-2N1 oral and oropharyngeal cancer\xa0without adequate neck dissection

Ching-Chieh Yang,Ching-Chih Lee,Bor-Hwang Kang,Wen-Shan Liu,Chun-Hao Yin

doi:10.1186/s13014-020-01736-8

Abstract

BackgroundTo assess the benefit of postoperative radiotherapy in patients with pT1-2N1M0 oral and oropharyngeal cancer by the quality of neck dissection.MethodsIn the Surveillance, Epidemiology, and End Results database, pT1-2N1M0 oral and oropharyngeal cancer patients treated by primary tumor resection and neck dissection with or without radiotherapy were included between 2004 and 2015. Univariate and multivariate analysis were used to explore the effect of adjuvant radiotherapy on 5-year overall survival (OS) and disease-specific survival (DSS) among different quality of neck dissection.ResultsOf the 1765 patients identified, 1108 (62.8%) had oral cancer, 1141 (64.6%) were men, and 1067 (60.5%) underwent adjuvant radiotherapy. After adjusting for confounding factors, postoperative radiotherapy reduced the adjusted hazard ratio (aHR) of 5-year OS to 0.64 (95% confidence interval [CI] 0.49–0.84) in those with < 18 lymph nodes (LNs) removed, but not in those with 19–24 LNs removed (aHR 0.78; 95% CI 0.73–1.13), and in those with ≥ 25 LNs removed (aHR 0.96; 95% CI 0.75–1.24). For 5-year DSS, similar effect was observed. The adjusted hazard ratio was 0.66 (95% confidence interval, 0.45–0.97) in those with < 18 LNs. The protective effect was not seen in those with 18–24 LNs (aHR 1.07; 95% CI 0.59–1.96), and in those with ≥ 25 LNs (aHR 1.12; 95% CI 0.81–1.56). Sensitivity testing also showed a robust protective effect of postoperative radiotherapy in patients with < 18 LNs removed.ConclusionRadiotherapy was associated with improved survival in pT1-2N1M0 oral and oropharyngeal cancer patients without adequate neck dissection.

Highlights

To assess the benefit of postoperative radiotherapy in patients with pT1-2N1M0 oral and oropharyn‐ geal cancer by the quality of neck dissection
Ebrahimi et al reported that an lymph nodes (LNs) yield < 18 was associated with worse 5-year overall, disease-specific (HR 2.2; 95% Confidence interval (CI) 1.1–4.5), and disease-free survival (HR 1.7; 95% CI 1.1–2.8)
In contrast to the latest National Comprehensive Cancer Network (NCCN) guidelines which suggest adjuvant radiotherapy for patients with pT1-2N1 disease, our results demonstrated that postoperative radiotherapy was effective only in those without good-quality neck dissection (LN yield < 18) [4, 14]

Summary

Introduction

To assess the benefit of postoperative radiotherapy in patients with pT1-2N1M0 oral and oropharyn‐ geal cancer by the quality of neck dissection. Oral and oropharyngeal cancer remain among the most common malignancies in the world [1]. Most early stage oral and oropharyngeal patients have a favorable prognostic outcome, previous literatures have reported locoregional recurrence in 30–35% of patients, Yang et al Radiat Oncol (2021) 16:6. Cervical positive LNs, those most commonly related to recurrence, are recognized as among the most important prognostic factors in head and neck cancer [6]. LN yield ≥ 18 has been proposed as a cut-off point for good-quality neck dissection. Postoperative radiotherapy was considered in those with pN1 disease, scant studies investigated the survival benefit of postoperative radiotherapy for those without adequate LN dissection

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Discussion

Conclusion