Inferring the effects of concurrent chemotherapy with or without adjuvant chemotherapy versus radiotherapy alone in stage II-IVB nasopharyngeal carcinoma: Comparison of results from meta-analysis of observational studies and randomized trials.

Abstract

e17573 Background: Multiple randomized trials (RCTs) reported that concurrent chemotherapy (CCT) with or without adjuvant chemotherapy (AC) improves survival in stage II-IVB nasopharyngeal carcinoma (NPC) compared to radiation therapy alone. However, it is unclear if similar benefits can be observed in routine practice as patients included in RCTs could be very different from patients in routine practice. The aim of this study is to compare the effects of CCT with or without AC as estimated from observational studies (OBS) with findings from RCTs. Methods: We searched MEDLINE for eligible studies determining the effect of addition of CCT with or without AC in stage II-IVB NPC. Outcome of interest was overall survival (OS). We performed the meta-analysis with random effects model to estimate the pooled hazard ratios (HR), confidence intervals (CI), and I squared statistic (I2) for both RCTs and OBS and compared them using Altman interaction test. Results: We found nine RCTs and 19 OBS including 6523 patients. Eight RCTs and 14 OBS had at least 75% of its patients with stage III-IVB NPC while only one RCT and five OBS had at least 75% of its patients with stage II NPC. The survival benefit associated with chemotherapy was similar in both RCTs and OBS focusing on stage III-IVB NPC (RCTs HR 0.67, 95% CI 0.56 – 0.81, I2 = 48% vs OBS HR 0.71 95% CI 0.62 – 0.82, I2 = 4%, interaction P (IP) = 0.67). Similarly, there was no significant difference in OS for RCT and OBS focusing on stage II NPC (RCTs HR 0.34, 95% CI 0.17 to 0.66, I2 = non-applicable due to single study vs OBS HR 0.61, 95% CI 0.37 to 1.02, I2 = 0%, IP = 0.17). Conclusions: Patients with stage II and stage III-IVB nasopharyngeal carcinoma treated in routine practice received similar survival benefits associated with concurrent chemotherapy with or without adjuvant chemotherapy as patients treated in randomized trials.