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

•Parotid cancer patients with facial weakness had poor clinical outcomes.•Facial weakness did not always indicate tumor invasion of the facial nerve.•Decision of facial nerve resection can be further based on intraoperative findings.•Outcomes of facial nerve graft were poor due to short disease-free intervals.•In selected cases, facial nerve preservation offers the best functional outcomes.