A prospective study to determine the safety and efficacy of contralateral submandibular gland-sparing radiation therapy for oral cavity and oropharyngeal carcinoma

Background and Aim: The submandibular glands (SMGs) contribute 95% of daily salivary flow. Thus, SMG-sparing intensity-modulated radiation therapy (IMRT) may maximize patient-related xerostomia outcomes. However, sparing the SMG is technically quite challenging due to its small size and proximity with suspected disease harboring target lymph node groups. In this study, we assessed the effects of the contralateral SMG (cSMG)-sparing radiation therapy on the treatment outcome and on the xerostomia and other toxicities. Materials and Methods: Patients with squamous cell carcinoma of oral cavity and oropharynx with only unilateral neck node involvement were given cSMG-sparing IMRT either as definitive or postsurgery adjuvant therapy depending on the scenario. During radiotherapy, patients were followed up weekly and after completion of radiation at 6 weeks, 3 months, and at 6 months for assessment of treatment response and evaluation of xerostomia and other toxicities. Results: The mean dose to the cSMG was 33.68 Gy. Immediately after radiotherapy, 25.7% of patients had Grade 2 acute xerostomia which on subsequent follow-up on 3 and 6 months reduced to only 2.9%. In patients, who received postoperative radiotherapy with or without chemotherapy, no incidence of recurrence was noted in the entire follow-up period. About 57.1% of patients who received definitive concurrent chemoradiotherapy showed complete response after 6 months. Conclusion: In well-lateralized oropharyngeal and oral cavity carcinoma, cSMG-sparing IMRT can limit the incidence of xerostomia without compromising tumor control.