Differential benefit of induction chemotherapy according to body mass index in nasopharyngeal carcinoma – Pooled analysis of two randomized trials

Induction chemotherapy followed by concurrent chemoradiotherapy is the standard of care for patients with locoregionally advanced nasopharyngeal carcinoma (NPC). However, survival benefits from additional induction chemotherapy varied significantly among patients. This study aimed to determine the predictive value of body mass index (BMI) in induction chemotherapy in NPC.This post-hoc analysis included patients from two multicenter, randomized, phase 3 trials (NCT01245959 and NCT01872962), in which patients were randomized to receive induction chemotherapy plus concurrent chemoradiotherapy or concurrent chemoradiotherapy alone.Among 960 patients participated, 957 were included in this analysis. 82 (8.6%) patients had baseline BMI < 18.5 kg/m2 (underweight) and 875 (91.4%) had BMI ≥ 18.5 kg/m2 (normal /overweight). Higher proportion of normal/overweight patients completed ≥2 cycles of induction chemotherapy than underweight patients (96.5% vs. 88.4%, p = 0.042). A strong trend for interaction was observed between BMI and induction chemotherapy regarding failure-free survival (FFS) and overall survival (OS, both pinteraction < 0.001). Normal/overweight patients benefited from induction chemotherapy regarding FFS (83.8% vs. 72.9%, p < 0.001) or OS (93.1% vs. 86.9%, p < 0.001), while underweight patients did not (p = 0.24 and p = 0.65, respectively). These results were confirmed in multivariate analysis and multiple sensitivity analyses.Using pooled data from two landmark phase III trials, we found that underweight patients might not benefit from additional induction chemotherapy in locoregionally advanced NPC. If confirmed in prospective studies, this could help guide individual treatment in the clinic.