PET scan-directed chemoradiation for esophageal squamous cell carcinoma: no benefit for a change in chemotherapy in PET non-responders.

INTRODUCTION: Pre-operative or definitive chemoradiation is an accepted treatment for locally advanced esophageal squamous cell carcinoma (ESCC). The MUNICON study demonstrated that PET response following induction chemotherapy was predictive of outcomes in patients with gastroesophageal junction adenocarcinoma. We evaluated the predictive value of PET following induction chemotherapy in ESCC patients and assessed the impact of changing chemotherapy during radiation in PET non-responders.

METHODS: We retrospectively reviewed all patients with locally advanced ESCC who received induction chemotherapy and chemoradiation; all patients had a PET before and after induction chemotherapy. Survival was calculated from date of repeat PET using Kaplan-Meier analysis and compared between groups using the log-rank test.

RESULTS: Of 111 patients, 70 (63%) were PET responders (defined as ≥35% decrease in maximum standard uptake value) to induction chemotherapy. PET responders received the same chemotherapy during radiation. Of 41 PET non-responders, 16 continued with the same chemotherapy and 25 were changed to alternative chemotherapy with radiation. Median progression-free (PFS; 70.1 vs. 7.1 months, p<0.01) and overall survival (OS; 84.8 vs. 17.2 months, p<0.01) were improved for PET responders vs. non-responders. Median PFS and OS for PET non-responders who changed chemotherapy vs. those who did not were 6.4 vs. 8.3 months (p=0.556) and 14.1 vs. 17.2 months (p=0.81), respectively.

CONCLUSIONS: PET after induction chemotherapy highly predicts for outcomes in ESCC patients who receive chemoradiation. However, our results suggest that PET non-responders do not benefit from changing chemotherapy during radiation. Future trials should utilize PET non-response after induction chemotherapy to identify poor prognosis patients for novel therapies.