Definitive radiotherapy vs. postoperative radiotherapy for lower gingival carcinomas of the mandible : A single-center report about outcome and toxicity.

Objective: To assess radiotherapy (RT) outcomes in patients with gingival carcinoma and growth up to or involvement of the lower jaw bone.

Methods: This was a retrospective analysis of 51 patients with squamous cell carcinomas of the gingiva. Patients received definitive (group 1, 31.4%) or postoperative (group 2, 66.7%) RT between 2005 and 2017 at the Department of Radiation Oncology, University Hospital Heidelberg. The primary endpoint was overall survival (OS) in both treatment groups. Other endpoints were local-disease-free survival (LDFS), progression-free survival (PFS) and treatment-related toxicity (Common Terminology Criteria for Adverse Events, CTCAE, Version 4.03).

Results: Median age at first diagnosis was 63 years. All patients had a local advanced disease (American Joint Commission on Cancer [AJCC] stage III-IV). After a median follow-up of 22 months (range 3-145 months), 20 patients (39.2%) were still alive. At 5 years, OS rate was 36.6%. No significant differences in OS (p = 0.773), PFS (p = 0.350) and LDFS (p = 0.399) were observed between the two groups. Most common higher-grade acute RT-related complications (≥ grade 3) were dermatitis (78.2%), oral mucositis (61.7%), xerostomia (51.5%), and loss of taste (74.6%). Three cases (5.8%) of osteoradionecrosis (ORN) of the lower jaw were detected after 15-31 months.

Conclusions: Definitive and postoperative RT have similar treatment outcomes for patients with lower gingiva carcinomas of the lower jaw. The most common acute complications (grade ≥3) were dermatitis, oral mucositis, xerostomia and loss of taste.