Treatment outcomes in nasopharyngeal carcinoma patients with parotid lymph node metastasis: An 11-year experience at a tertiary cancer center.

Abstract

Parotid lymph node (PLN) metastasis in nasopharyngeal carcinoma (NPC) is rare, with limited data guiding its management and prognosis. We retrospectively analyzed 6924 non-metastatic NPC patients at our tertiary cancer center, identifying 126 patients with PLN metastasis confirmed by fine-needle aspiration cytology (FNAC) and magnetic resonance imaging (MRI). Survival outcomes and prognostic factors were assessed using Kaplan-Meier estimates, log-rank tests, propensity score matching (PSM), and Cox regression. Compared to patients with N3 disease, those with PLN metastasis had worse regional relapse-free survival, distant metastasis-free survival, and progression-free survival. However, overall survival was not significantly affected. When PLN received radical-intensity radiation doses, outcomes were comparable to patients without PLN metastasis. Treatment failures with PLN involvement frequently co-occurred with regional relapse and distant metastasis. Among patients who were treated with PLN-sparing intensity-modulated radiotherapy (IMRT), compared to non-parotid relapse patients, parotid relapse patients were older, had more advanced N classification, lower baseline Epstein-barr virus DNA (EBV-DNA) level, and received fewer cycles of chemotherapy. Additionally, these recurrent PLNs were characterized by smaller size, being typically unilateral and isolated, exhibiting poor sensitivity to chemotherapy, and receiving lower doses of radiotherapy. In our study, PLN metastasis does not upstage the patient's N classification if comprehensive radiotherapy is administered at radical doses. We advise prudence when implementing parotid-sparing IMRT and strongly recommend FNAC for clinically suspicious lesions.