The role of adjuvant (chemo-)radiotherapy in oral cancers in the contemporary era

Squamous cell carcinoma of oral cavity (OSCC) is predominantly managed with surgery. Post-operative radiotherapy (PORT) and chemoradiotherapy (POCRT) enhance disease control in OSCC patients with adverse anatomic and pathologic primary and nodal features. Knowledge about disease behavior, surgery and radiotherapy advances, and the emergence of new systemic agents prompt refinement of PORT volumes and POCRT regimens. Traditional and emerging prognostic models that include adverse histopathological features underpin such approaches. This review summarizes research over recent decades with emphasis on the 2015 to Feb 2019 period describing: (1) Indications for PORT and/or POCRT, addressing surgical margin status including the definition of a clear margin to permit withholding PORT/POCRT; these concepts include characterizing the specimen yielding these measurements, the optimal time point to assess these findings, and the putative value of a revised margin performed during the same operative procedure, (2) Emerging prognostic factors including nodal burden (total number of involved lymph nodes) and perineural invasion, (3) PORT volume design, dose/fractionation and optimal surgery-to-PORT interval, (4) Chemotherapy dose, schedule, and agents, and (5) On-going clinical trials involving systemic agents and combinations of chemotherapy with immunotherapy.