Clinical outcomes and management of facial nerve in patients with parotid gland cancer and pretreatment facial weakness.

OBJECTIVES: In parotid gland cancer (PGC), it is not clear whether facial weakness always reflects tumor invasion of the facial nerve (FN) requiring nerve resection. The aims of this study were to evaluate oncological and functional outcomes in patients with PGC and pre-treatment facial weakness, and to analyze local tumor invasion of the FN. MATERIALS AND METHODS: The clinical outcomes of patients (n = 45) with PGC and pretreatment facial weakness were retrospectively analyzed. Patients had undergone 1 of 4 types of treatments: complete tumor resection, FN sacrifice with or without FN reconstruction, tumor resection with FN preservation and primary non-surgical treatments. Pathologic specimens in patients with nerve resection patients (n = 26) were reviewed to identify FN invasion by the tumor. RESULTS: Patients with PGC and facial weakness had poor clinical outcomes (44.0%, 3Y progression-free survival), and 86.7% of tumors were high-grade. In these subjects, regional or distant metastasis was an independent prognostic factor for survival. Recovery from facial weakness was suboptimal in patients with FN graft. In cases with nerve resection, 26.9% had intra-neural tumor invasion, 42.3% had perineural invasion, and 30.8% had no neural invasion in the FN. CONCLUSION: Facial weakness did not always indicate tumor invasion of the FN in PGC. Thus, the decision regarding FN resection can reasonably be further based on intraoperative findings. In cases with incomplete facial weakness and safe separation of the FN from the tumor, FN preservation offers the best functional outcomes, without compromising oncological outcomes.