Treatment outcomes and failure patterns in postoperative radiotherapy for major salivary gland carcinoma

Surgery is the standard of care for major salivary gland carcinoma (MSGC), and postoperative radiotherapy (PORT) is used for patients at high risk of postoperative recurrence.

We retrospectively analyzed 32 patients with MSGC treated with PORT between 2010 and 2019. All patients had one or more of the following high-risk factors for recurrence: histologically high-grade, T3-4 tumors, positive or close margins, lymph node (LN) metastasis, and perineural invasion.

The median age of the patients was 63 years (range, 18-81 years). Stage I, II, III, and IV disease were observed in 2, 5, 7, and 18 patients, respectively. Twenty-two patients underwent concurrent systemic therapy. The most commonly irradiated areas were the primary lesion and ipsilateral neck (78%). The 5-year overall survival (OS), recurrence-free survival (RFS) and locoregional control rates were 49%, 31%, and 77%, respectively. The 5-year OS rates were 86% for Stages I-III, and 22% for Stage IV. The 5-year RFS rates were 57% for Stages I-III, and 11% for Stage IV. Recurrence occurred in 22 patients. The most common pattern of recurrence was pulmonary metastases (34%). There were seven cases of cervical LN metastasis at the time of first recurrence, and five of these cases showed cervical LN metastases outside the irradiated area.

We reported the results of PORT in patients with MSGC. Although the incidence of in-field recurrence was low, recurrence from outside the irradiated area was common, suggesting the need for further investigation into the optimal systemic therapy and radiation extent.