The Role of Adjuvant Radiotherapy in Locally Advanced T4 Mandible Squamous Cell Carcinoma in the N0 Patient: a Single Centre Experience

In locally advanced oral squamous cell carcinoma (OSCC), namely that showing invasion of the mandible, demonstrating no high-risk (e.g. extranodal extension, positive margin) or intermediate-risk histopathological features (e.g. perineural invasion, lymphovascular invasion), the additional benefit of postoperative radiotherapy (PORT) currently remains uncertain. A retrospective review covering the period between January 1, 2010 and December 31, 2019 was conducted to identify patients from a single UK centre with locally advanced invasive mandibular OSCC defined as pT4a, with no nodal or distant metastasis (N0 M0). The primary outcome was to determine the disease-free survival and overall survival rates in the surgery + PORT group, in comparison to the surgery only group. Twenty-eight eligible patients were identified, with 13 patients in the surgery + PORT group and 15 patients in the surgery only group. A single patient in the surgery + PORT group developed disease recurrence and subsequently died (1/13) (median follow-up 5.24 years, range 2.13-10.71 years). No patient in the surgery only group developed disease recurrence or died (0/15) (median follow-up 5.13 years, range 1.37-10.93 years). It may be reasonable to consider omitting PORT in pT4a pN0 M0 OSCC of the mandible in patients who demonstrate no high- or intermediate-risk histopathological features, following multidisciplinary team discussion.