Interfraction interval in patients with stage III non-small-cell lung cancer treated with hyperfractionated radiation therapy with or without concurrent chemotherapy - Final results in 536 patients

We investigated the influence of interfraction interval (IFI) on treatment outcome in patients with stage III non-small-cell lung cancer (NSCLC) treated with hyperfractionated radiation therapy (Hfx RT) with or without concurrent chemotherapy (CHT). During 3 randomized phase III and 1 phase II study, a total of 536 patients were treated with Hfx RT alone or with concurrent carboplatin/etoposide. Two hundred eighty-five patients were treated with IFI of 4.5-5.0 hours, while 251 patients were treated with IFI of 5.5-6.0 hours. "Shorter" (4.5-5.0 hours) IFI led to better overall survival (OS) (P = 0.0000) and local recurrence-free survival (LRFS) (P = 0.0000). Multivariate analyses showed IFI to be an independent prognosticator of both OS and LRFS. These results were confirmed when we separated all patients (n = 536) into those treated with Hfx RT only (n = 127) and those treated with concurrent RT/CHT (n = 409). Various RT-related high-grade acute toxicity was not different between the 2 IFI, but patients treated with shorter IFI had a significantly higher incidence of hernatological toxicity (P = 0.002). None of the late high-grade toxicities were different between the 2 interfraction intervals. Using regression analysis, it was shown that IFI was not a significant predictor of any of acute or late high-grade (greater than or equal to 3) toxicity. IFI is an important prognosticator of OS and LRFS in patients with stage III NSCLC treated with Hfx RT with or without concurrent carboplatin/etoposide. IFI led to higher incidence only of hernatological toxicity, but was not predictive of any acute or late high-grade ( greater than or equal to3) toxicity. A carefully designed randomized trial seems necessary to give better insight into the issue of optimal IFI in this disease.