The role of radiologic extranodal extension in predicting prognosis and chemotherapy benefit for T1-2 N1 nasopharyngeal carcinoma: A multicenter retrospective study

Abstract

Background and purpose: This multicenter retrospective study aimed to investigated the prognostic value of unequivocal radiologic extranodal extension (rENE) and the efficacy of chemotherapy for stage T1-2 N1 nasopharyngeal carcinoma (NPC) in the IMRT era.

Materials and methods: We included 1,082 patients treated in 2005-2017 from three centers. rENE was recorded as G1 (coalescent nodal mass comprising ≥ 2 inseparable nodes) or G2 (invading beyond perinodal fat to frankly infiltrate adjacent structures). Multivariable analysis (MVA) evaluated the prognostic value of rENE. The value of chemotherapy was assessed in rENE-positive (rENE + ) and rENE-negative (rENE - ) subset separately.

Results: Centers 1, 2, and 3 had 139/515 (27.0 %), 100/365 (27.4 %), and 43/202 (21.3 %) cN + patients with rENE, respectively. Compared to rENE-, rENE + patients had a worse distant metastasis-free survival (DMFS) and overall survival (OS) (all p < 0.001). MVA confirmed the prognostic of both G1-rENE and G2-rENE for distant metastasis [G1: hazard ratio (HR): 2.933, G2: HR: 6.942, all p < 0.001] and death (G1: HR: 1.587, p = 0.040; G2: HR: 6.162, p < 0.001). There was no significant difference for DMFS and OS between chemo-radiotherapy and radiotherapy alone in rENE + and rENE - groups (all p > 0.1). However, rENE + patients with a cumulative cisplatin/nedaplatin dose (CCND) of > 160 mg/m² had an improved DMFS (p = 0.033) but no OS (p = 0.197).

Conclusion: Unequivocal rENE is prognostic in patients with T1-2 N1 NPC. Addition of chemotherapy to radiotherapy did not affect DMFS and OS in rENE - patients. Chemotherapy with a CCND of > 160 mg/m² improved DMFS in rENE + patients.

Keywords: Chemotherapy; Distant metastasis; Nasopharyngeal carcinoma; Radiologic extranodal extension; Stage T1-2N1.