Treatment implications of postoperative chemoradiotherapy for squamous cell carcinoma of the oral cavity with minor and major extranodal extension

Objectives: To evaluate adjuvant chemoradiotherapy (CRT) for patients with oral cavity squamous cell carcinoma (OSCC) with minor or major extranodal extension (ENE). Materials and methods: Surgically resected OSCC with pathologically involved lymph node(s) (pN + ) between 2006 and 2017. Sections of pN+ were re-reviewed and classified as no, minor (<= 2 mm), or major ( > 2 mm) ENE. Patterns of failure and survival were compared between the groups and stratified by adjuvant treatment. Multivariable (MVA) analysis assessed the value of adjuvant treatment for minor and major ENE. Results: Total of 384 patients, 62 had minor and 114 had major ENE. Adjuvant CRT was delivered in 32(15%), 21(34%), and 45(39%) of patients with no, minor and major ENE, respectively. Patients with minor ENE had similar 5-year loco-regional control (LRC) and distant control (DC) but lower disease-free survival (DFS) (38% vs. 51%, p = 0.02) compared to patients with no ENE, while patients with major ENE had marginally lower LRC (59% vs 74%, p = 0.07), lower DC (58% vs 82%,p = 0.005) and DFS (13% vs. 38%, p =11)01) compared to those with minor. On MVA, adjuvant chemotherapy was associated with improved DFS for major ENE (adjusted HR = 0.49; 95% CI 0.29-0.85, p = 0.01) but not for minor ENE after adjusting for age, ECOG status, T-, N-category, margin status, and radiotherapy. Conclusions: Adjuvant chemoradiotherapy improves outcomes in patients with major ENE, but the benefit is unclear in patients with minor ENE. Future trials should focus on intensification of treatment for patients with major ENE and alternative adjuvant strategies for patients with minor ENE.