Distribution of regional lymph lode metastasis in unilateral nasopharyngeal carcinoma and the suggestions for selective prophylactic irradiation with intensity-modulated radiotherapy.

PURPOSE: To address the regional lymph node (RLN) distribution and the long-term efficacy in unilateral nasopharyngeal carcinoma (NPC), providing elective irradiation for RLN with intensity-modulated radiotherapy (IMRT). METHODS: The involvement of clinical data of 136 patients with unilateral NPC, who underwent IMRT from November 2003 to December 2020 were analyzed retrospectively. The therapeutic effect and failure pattern of RLN metastasis were evaluated. RESULTS: Of 57.1% patients have bilateral RLN metastasis. The rate of contralateral RLNs metastasis is lower than that of ipsilateral RLNs. Contralateral RLN metastasis mainly occurs in level VIIa (39.0%) and II (38.2%). While level IVa is only 0.7%, and none of RLN metastasis was found in level IVb and Va. The median follow-up was 70 months, and the 3-, 5-and 10-year regional recurrence-free survival (RRFS) were 94.1%, 93.1%, and 93.1%, respectively. CONCLUSION: Routine prophylactic irradiation may not include contralateral lower neck LN and level Va for N0-1 unilateral NPC.