Mucoepidermoid Carcinoma of the Parotid: Very Close Margins and Adjuvant Radiotherapy

Abstract

Background/Aims: The importance of adjuvant radiotherapy in patients with close margin resections for mucoepidermoid carcinoma of the parotid gland remains unclear. Methods: Patients who underwent parotidectomy for mucoepidermoid carcinoma with or without adjuvant radiotherapy at a single academic tertiary care center from 2000 to 2014 were identified. Included patients had negative but close (≤2 mm) surgical margins without other high-risk histopathological factors including advanced T-stage, positive nodal disease, lymphovascular or perineural invasion, or high-grade histology. Results: Nineteen patients were identified, of whom 15 (79%) were observed postoperatively, while 4 (21%) underwent adjuvant radiotherapy. There were no significant differences in extent of parotidectomy, elective neck dissection, T staging, or tumor size between patients who were observed and those undergoing adjuvant radiation. There were no locoregional or distant recurrences in any patients at a mean follow up 74.3 months. Patients undergoing adjuvant radiation, however, had significantly more intermediate-grade as compared to low-grade histology (75% vs. 13%, difference 62%, 95% CI 4% to 100%). Conclusions: Patients with negative but close (≤2 mm) surgical margins without other high-risk histopathological factors have excellent long-term locoregional control with surgery alone. The effects of adjuvant radiotherapy for those who have intermediate-grade disease remain uncertain.

Management of Salivary Gland Malignancy: ASCO Guideline

“…Despite this, early-stage low-and intermediategrade parotid cancers have been shown to have excellent disease control when managed with complete surgical resection, even with narrow surgical margins, in the absence of adverse features such as perineural or lymphovascular invasion or pathologic nodal disease. [319][320][321][322] Zenga et al 321 demonstrated a 100% locoregional control at a mean follow-up of 74 months in a series of 15 patients with T1-2N0 low-or intermediate-grade mucoepidermoid cancer managed with surgery alone, despite a surgical margin of # 2 mm. Similarly, in a series of 18 patients with early-stage acinic cell carcinomas of the parotid gland without adverse features (pathologic nodal disease, lymphovascular or perineural invasion, or high-grade histology), only one patient experienced a recurrence with a median follow-up of 64 months.…”

“…In earlystage low-and intermediate-grade parotid cancers, complete surgical resection with close margins has been shown to result in excellent disease control, supporting the concept of facial nerve preservation in these patients. [319][320][321][322] For advanced and high-grade tumors, it is less clear. In a retrospective series of 107 patients undergoing parotidectomy for parotid cancer, Guntinas-Lichius et al 131 used the following criteria for nerve resection: preoperative nerve weakness confirmed by electromyography believed to be related to the tumor or intraoperative suspicion of tumor infiltration of the nerve.…”

Nomogram to predict the prognosis of parotid gland mucoepidermoid carcinoma: a population-based study of 1306 cases

“…Traditionally, radiotherapy was applied in P-MEC patients with high grade, advanced stage, and unresectable and recurrent tumors. Nevertheless, radiotherapy may result in fatigue and pain, ototoxicity, xerostomia, radiation fibrosis, and radiation-induced malignancy (Chen et al, 2013; Brusic et al, 2012; Zenga et al, 2019). Zenga et al (2019) reported that P-MEC patients with negative but close (≤2 mm) surgical margins without other high-risk histopathological factors did not benefit from adjuvant radiation in terms of long-term locoregional control.…”

Efficacy of surgery combined with postoperative 125I interstitial brachytherapy for treatment of acinic cell carcinoma of the parotid gland in children and adolescents

“…According to the literature, surgical resection remains the mainstay treatment for AciCC of the parotid gland (PG), and patients with lowgrade, early T stage (T1/T2) disease, without high-risk clinicopathological features, can be managed using surgery alone. [15][16][17][18] Zenga et al…”

“…[7][8][9] Due to its rarity, previous studies of AciCC in children and adolescents have predominately been reported as case series, 10-14 and it is challenging to develop a consensus on its management.According to the literature, surgical resection remains the mainstay treatment for AciCC of the parotid gland (PG), and patients with lowgrade, early T stage (T1/T2) disease, without high-risk clinicopathological features, can be managed using surgery alone. [15][16][17][18] Zenga et alreported that, if the only risk factor was close (≤ 1 mm) margins, AciCC…”