Administration of oral maintenance chemotherapy for 1 year following definitive chemoradiotherapy may improve the survival of patients with stage N3 nasopharyngeal carcinoma.

Objectives: This study aims to evaluate the effectiveness and the optimal maintenance period of oral chemotherapy using S1 following definitive chemoradiotherapy in patients with stage N3 nasopharyngeal carcinoma (N3-NPC).

Materials And Methods: A retrospective review was performed for N3-NPC treatment with maintenance chemotherapy (MC) [chemoradiotherapy (CRT)-MC] or without MC (CRT-non-MC) following definitive CRT between May 2014 and December 2017. Toxicities during MC were recorded. Overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS) and locoregional relapse-free survival (LRRFS) were compared between CRT-MC and CRT-non-MC cohorts. The optimal duration of using maintenance S1 (MC-S1) was also analyzed.

Results: A total of 304 patients with stage N3-NPC were identified, of whom 56 were treated with CRT-MC and 248 with CRT-non-MC. After a median follow-up of 48 months, significant differences in OS (74.9 vs. 91.7%; P = 0.003), PFS (60.7 vs. 83.7%; P = 0.001) and DMFS (68.8 vs. 85.5%; P = 0.015) were observed between the CRT-non-MC and CRT-MC groups. Skin hyperpigmentation, leukopenia and fatigue were common but not severe (grade 1-2) side effects of MC. The OS, DMFS and PFS were significantly higher for patients who received S1 administration over a period of ≥12 cycles compared with those who received <12 cycles (3-year OS, 100 vs. 87.5%, P = 0.018; 3-year PFS, 93.9 vs. 67.9%, P = 0.006; 3-year DMFS, 97.1 vs. 67.9%, P = 0.002).

Conclusions: Using MC-S1 in patients with N3-NPC following definitive chemoradiotherapy achieved superior survival rate compared with the patients with non-MC. The side effects of MC-S1 were mild and tolerable. S1 should be maintained for ≥12 cycles.