Addition of definitive radiotherapy to chemotherapy in patients with newly diagnosed metastatic nasopharyngeal cancer

Background: Management of metastatic (M1) nasopharyngeal cancer (NPC) is controversial; data suggest high overall survival (OS) rates with definitive chemoradiotherapy (CRT). Herein, we evaluated OS in patients with M1 NPC undergoing chemotherapy alone versus CRT. Methods: The National Cancer Data Base was queried for M1 NPC cases. Patients undergoing no/unknown chemotherapy and/or with unknown/nondefinitive radiotherapy (RT) doses (<60 Gy) were excluded. Logistic regression analysis ascertained clinical factors associated with RT administration. Kaplan-Meier analysis evaluated OS between both cohorts; Cox proportional hazards modeling assessed factors associated with OS. Survival was then evaluated between matched populations using inverse-probability-weighted regression adjustment. OS between groups was also measured in patients surviving ≥1 and ≥3 years to address bias from poor-prognostic subsets (eg, widely disseminated disease), and those receiving CRT ≤30 and ≤60 days of each other (surrogates for concurrent CRT) versus >30 and >60 days (sequential) of each other. Results: Of 555 patients, 296 (53%) received chemotherapy alone and 259 (47%) underwent CRT. Patients undergoing CRT more often had private insurance (P=.001) and lived in areas with higher education levels (P=.028). Median OS in the chemotherapy-only and CRT cohorts were 13.7 and 25.8 months, respectively (P<.001); differences persisted between matched populations (P<.001). On multivariate analysis, receipt of additional RT independently predicted for improved OS (P<.001). OS differences between cohorts remained apparent when evaluating patients surviving for ≥1 (P<.001) and ≥3 (P=.002) years. Patients who received concurrent or sequential CRT displayed improved OS over those receiving chemotherapy alone, for both the 30-day (P<.001) and 60-day cutoffs (P<.001). Conclusions: Patients with M1 NPC undergoing definitive RT and chemotherapy experienced higher survival than those receiving chemotherapy alone. Risk stratification and patient selection for such combined modality interventions is critical.