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Modified Submandibular Gland Transfer Reduces Radiation Dose, Improves Xerostomia Outcomes

by Amy E. Hamaker •

What is the radiation-sparing capacity and xerostomia-reducing potential of the modified submandibular gland transfer (M-SGT) for head and neck cancer patients who receive radiation therapy (RT)?

Bottom line: The M-SGT successfully reduces the radiation dose sustained by the SMG during adjuvant treatment and provides a significant improvement in xerostomia-related functional outcomes.

Background: One of the most common sequelae of head and neck cancer treatment is radiation-induced xerostomia. The SGT procedure is contraindicated in oral cavity primaries because the submental area cannot be effectively or safely shielded from radiation. The M-SGT relocates the submandibular gland (SMG) contralateral to the disease to the periparotid region rather than the submental triangle.

Study design: Radiation therapy treatment plan review of 22 patients treated with surgery and RT who had an M-SGT between November 2013 and March 2016.

Setting: University of Alberta, Edmonton, Alberta, Canada.

Synopsis: Twenty patients were included in the xerostomia-related functional assessment, with two being deceased at follow-up. Primary cancer sites were in the oral cavity (18), the oropharynx with oral cavity extension (3), and hypopharynx with oral cavity extension (1). The mean radiation dose applied to the SMG within the periparotid space (29.0 grays [Gy]) was significantly less than the submandibular triangle (47.3 Gy). Furthermore, this reduction brought the mean radiation dose received by the transferred gland to well below the toxic dose for the SMG reported in the literature (34 Gy). Two patients of the historical controls who did not receive an SGT experienced “no xerostomia” as compared to 13 who received the M-SGT, a statistically significant difference. At a mean follow-up time of 15 months, 65% of patients who underwent the M-SGT had no xerostomia as compared to 16% of patients who did not receive any SGT, also a statistically significant difference. Limitations included the relatively small sample size, reliance on historical controls for the patient-rated xerostomia scores, and a lack of objective salivary flow measures.

Citation: Murray S, Chung J, Zhang H, et al. Functional outcomes of the modified submandibular gland transfer procedure. Laryngoscope. 2020;130(4):925-929.