Induction or Adjuvant Chemotherapy in Patients with Locally Advanced Nasopharyngeal Cancer Receiving Chemoradiotherapy? A Turkish Oncology Group Study

Background/Objectives: In this retrospective study, we aimed to compare the efficacy, survival, and toxicity results of induction (IC) or adjuvant (AC) treatment with chemoradiotherapy (CRT) in locally advanced nasopharyngeal cancer (NPC). Methods: A total of 405 patients from 22 different centres in Turkey, belonging to the Turkish Oncology Group (TOG), was included. The primary endpoints were overall survival (OS) and progression-free survival (PFS), and the secondary endpoints were safety and toxicity. Results: The median age of the patients included in the study was 49 (18.2–91.5) years. In total, 298 (73.6%) of the patients were male. Of the 405 patients, 258 (63.7%) received IC and 147 (36.3%) received AC treatment. When OS and PFS analyses were performed in terms of age, gender, T and N stages, pathological features, and treatments received, no effect of any variable on prognosis was observed. For the overall group, the median estimated OS was 137.3 months (the Kaplan–Meier statistical method could not reach the 95% confidence interval [CI]). For the IC group, the median estimated survival was 137.3 months (95% CI: 111.4–163.3), whereas the Kaplan–Meier statistical method could not estimate survival for the AC group. No statistically significant difference was observed between IC and AC groups in terms of OS (p = 0.209) or PFS (p = 0.248). Grade 3–4 side effects were observed in 12% of patients in the IC group and 29.9% of patients in the AC group. Treatment was discontinued due to toxicity in 5 patients (1.9%) in the IC group and 18 patients (12.2%) in the AC group. Conclusion: No difference in OS or PFS was observed between AC and IC treatments. More grade 3–4 side effects were observed in the AC-treated group and early discontinuation rate was higher.