Prognostic Factors and Survival Outcomes in Parotid Gland Mucoepidermoid Carcinoma: A Systematic Review with Meta-Analysis and Workflow Proposal

Objective: Mucoepidermoid carcinoma (MEC) is the most common malignant tumour of the parotid gland. This systematic review and meta-analysis aims to evaluate treatment strategies, survival, recurrence, and prognostic factors in primary parotid MEC. Materials and Methods: A systematic review was conducted following PRISMA guidelines. PubMed/MEDLINE, the Cochrane Library, Scopus, and Google Scholar were searched to identify eligible observational studies and clinical trials on primary parotid MEC. Pooled estimates of overall survival (OS), disease-specific survival (DSS), and local, regional, and distant recurrence rates were calculated. Prognostic factors associated with survival and recurrence were analysed. Results: Twenty-one studies involving 7192 patients were analysed. Histologic grade was low in 32.2%, intermediate in 41.8%, and high in 26.1%. Surgical treatment included total parotidectomy (2606 patients) and superficial parotidectomy (1642), with facial nerve preservation achieved in 1993 of 4111 reported cases. Positive margins occurred in 18% of patients, and postoperative radiotherapy was administered in 50%. Mean follow-up was 72.6 months. Pooled OS rates were 100% at 1 year, 90% at 5 years, and 70% at 10 years; DSS was 100% at 5 years and 90% at 10 years. Recurrence rates were 10% local, 0% regional, and 10% distant. High-grade histology, advanced T/N stage, positive surgical margins, and intraparotid lymph node metastasis were associated with poorer outcomes. Conclusions: Parotid MEC generally has favourable short- and intermediate-term outcomes. Based on evidence and institutional experience, we propose a grade-based workflow integrating tumour grade, T/N status, and adverse pathological features to guide surgical extent, elective neck dissection, and adjuvant radiotherapy. Prospective studies with standardized reporting are needed.