Mucoepidermoid carcinoma of the head and neck: CRTC1/3 MAML 2 translocation and its prognosticators

Abstract

Purpose Mucoepidermoid carcinoma (MEC) of the head and neck is a prevalent malignant salivary gland tumour with a reported good outcome. The aim of this study was to report the outcome in our centre. Methods A retrospective chart analysis with survival analyses was performed combined with fluorescence in situ hybridization (FISH) analysis to assess CRTC1/3 MAML 2 fusion gene presence. Results Sixty-four cases of MEC were identified. Median age at presentation was 51.4 years with a predominance for parotid gland involvement. Five, 10- and 20- year disease-free survival was 98%, 90% and 68%, respectively. Overall survival was 94%, 90% and 64%, respectively. Local recurrence was seen up to 14 years after primary diagnosis; distant metastases were diagnosed up to 17 years later. The overall recurrence rate was less than 20 per cent. CRTC1/3 MAML 2 fusion gene presence showed no survival benefit. Conclusion MEC of the head and neck has a favorable outcome with the exception of high-grade MEC. PNI and nodal involvement are not rare. CRTC1/3 MAML 2 fusion gene presence showed no survival benefit. The tendency for late onset of loco-regional and distant recurrence should not be underestimated.

Critical Appraisal of Histologic Grading for Mucoepidermoid Carcinoma of Salivary Gland

“…More recent studies with pathology review to confirm the diagnosis demonstrated a higher frequency of MAML2 translocation in MECs, being 56% to 92.5%. In addition, the presence of fusion did not correlate with histologic grade, recurrence, and/or survival 17,27,32,43–47 . Data from the present study further supported such observations.…”

“…The literature shows a 5-year DSS of MEC ranging from 95% to 99% 12,23,25,[29][30][31] and a 5-year RFS ranging from 77% to 96%. 10,14,23,25,27 Adverse prognostic factors that are identified previously in MEC and associated with recurrence include high histologic grade, 7,8,10,12,13,16,20,25 nodal metastasis, 8 advanced pT stage, 10,16,20 and PNI. 10 Similarly, we reported larger tumor size, advanced pT stage, LVI, positive surgical margin, and grade as prognostic factors for RFS.…”

“…Our results confirmed what was reported by multiple previous studies. The literature shows a 5-year DSS of MEC ranging from 95% to 99% 12,23,25,29–31 and a 5-year RFS ranging from 77% to 96% 10,14,23,25,27 …”

“…However, in the 2 most recent editions of the WHO classification (fourth edition in 2017 and fifth edition in 2022), grading of MEC is rather descriptive and subjective, 3,5 described as follows: “LG MECs are usually circumscribed, partly cystic and contain groups of mucous cells. IG MECs generally have more solid areas, while HG are solid with fewer mucous cells, and may display nuclear pleomorphism, mitotic figures, necrosis, and perineurial, lymphovascular or bony invasion.” Numerous studies have shown that histologic grade of MEC provides valuable prognostic information in predicting risk of nodal metastasis, recurrence, and mortality 6–27 . However, despite decades of efforts, there are still various grading systems for MEC have been among pathologists and a uniform widely accepted objective grading system has yet to be established.…”

“…Several recent studies have shown that LG and IG MECs have similar clinical behaviors with no significant differences in risk of nodal metastasis and outcome. 16,18,22,27,29 For example, in a Surveillance, Epidemiology, and End Results (SEER) database study including 2400 patients with parotid MEC, the diseasespecific survival (DSS) did not differ between LG and IG tumors but decreased significantly in HG tumors (5-y DSS: 98.8% for LG, 97.4% for IG, and 67.0% for HG). 18 Such an observation raises the question whether grading of MEC can be simplified into a 2-tiered system by combining LG and IG as one group.…”