18F-FDG PET/CT directed radiotherapy dose escalation in locally advanced esophageal cancer (LAEC), a phase I study.

Abstract

To determine the maximum tolerated dose (MTD) of hyperfractionated radiotherapy (HFRT) boost for residual metabolic disease (RMD) as defined by PET/CT following SCRT with concurrent paclitaxel (P) and carboplatin (C) for locally advanced esophageal cancer (LAEC). Eligible patients received standard chemoradiation therapy(SCRT) with weekly paclitaxel and carboplatin plus preirradiation PET/CT-guided intensity-modulated radiotherapy (IG-IMRT). Patients with RMD received HFRT boost concurrent with the same chemotherapy. Boost doses were escalated using a modified Fibonacci design. Dose limiting toxicity (DLT) was defined as grade ≥4 esophagitis, grade ≥3 non-hematological toxicity (except nausea/vomiting), or grade ≥4 hematological toxicity lasting >7 days. MTD was the highest dose with ≤1 pts experiencing DLT. 21pts were assessable. SCRT was well-tolerated. 4 pts achieved complete metabolic response (CMR). DLT occurred at 28.8 and 36 Gy. The MTD wasn't reached. The most common acute grade ≥ 3 toxicities were esophagitis (17 %), neutropenia (24 %). Late toxicity included grade 1 or 2 esophageal stricture (n = 5). Overall response rate was 88 %. With median follow-up of 9 months, local-regional failure only occurred in 1pt. 36 Gy HFRT boost to PET/CT-defined RMD after 50 Gy SCRT using IG-IMRT, resulting in a total composite tumor dose of 86 Gy (BED 100.32 Gy), can be safely delivered concurrent with weekly P/C. MTD remains to be defined.