Postoperative Radiotherapy for Malignant Tumors of the Submandibular Gland

Purpose: This retrospective study assessed the outcome and patterns of failure for patients with malignant submandibular tumors treated with surgery and postoperative radiation.

Methods And Materials: Between 1965 and 1995, 83 patients aged 11-83 years old received postoperative radiotherapy after resection of submandibular gland carcinomas. The most common radiation technique was an appositional field to the submandibular gland bed using electrons either alone or mixed with photons. Primary tumor bed doses ranged from 50 to 69 Gy (median, 60 Gy). Regional lymph nodes (ipsilateral Levels I-IV) were irradiated in 66 patients to a median dose of 50 Gy. Follow-up time ranged from 5 to 321 months (median, 82 months).

Results: Actuarial locoregional control rates were 90%, 88%, and 88% at 2, 5, and 10 years, respectively. The corresponding disease-free survival rates were 76%, 60%, and 53%, because 27 of 74 patients (36%) who attained locoregional control developed distant metastases. Adenocarcinoma, high-grade histology, and treatment during the earlier years of the study were associated with worse locoregional control and disease-free survival. The median survival times for patients with and without locoregional control were 183 months and 19 months, respectively. Actuarial 2-, 5-, and 10-year survival rates were 84%, 71%, and 55%, respectively. Late complications occurred in 8 patients (osteoradionecrosis, 5 patients).

Conclusions: High-risk cancers of the submandibular gland have a historic control rate of approximately 50% when treated with surgery alone. In the current series, locoregional control rates for high-risk patients with submandibular gland cancers treated with surgery and postoperative radiotherapy were excellent, with an actuarial locoregional control rate of 88% at 10 years.