Comparison of Pathologic Complete Response Rates and Outcomes in Patients Receiving Neoadjuvant Chemoradiation to 50.4Gy Vs 41.4 Gy in the Treatment of Surgically Resectable Esophageal Cancer

Abstract

The CROSS trial reported high rates of pathological complete response (pCR) and excellent outcomes with neoadjuvant chemoradiation for esophageal cancer with carboplatin and paclitaxel despite treating to only 41.4 Gy. With pCR rates comparable to historical series using 50.4 Gy, the question arises if there is any advantage to a higher dose in this population. This study compares pCR rates and outcomes in patients treated with 41.4 Gy vs 50.4 Gy in the neoadjuvant setting. We retrospectively reviewed the records of patients with esophageal adenocarcinoma (AC) or squamous cell carcinoma (SCC) treated with neoadjuvant chemoradiation with carboplatin/paclitaxel who underwent surgical resection. The primary endpoint was pCR rate. Secondary endpoints were progression free survival (PFS) and overall survival (OS). Groups were compared with Fischer exact test and t-test. Kaplan-Meier method was used to calculate PFS and OS with comparisons made with the log rank test. We identified a total of 33 patients treated with neoadjuvant chemoradiation followed by oncologic resection. 16 patients were treated with 41.4 Gy and 17 with 50.4 Gy. Cohorts were well matched with regard to age, clinical stage, tumor grade, ECOG performance status, and smoking history (all p>0.05). There were significantly higher frequencies of adenocarcinoma (13/16 vs 6/17) (p=0.007), lower-third of the esophagus primary (15/16 vs. 9/17) (p=0.026), and use of IMRT (11/16 vs. 5/17) (p<0.001)in the 41.4 Gy cohort vs 50.4 Gy. There was no difference in pCR rates (7/16 (43.8%) vs 8/17 (47.1%), p=0.563) between patients receiving 41.4 vs 50.4 Gy, respectively, even when correcting for AC vs. SCC. At a median follow up of 28 months, there was no difference in 3-year OS (73.3% vs 71.4% p=.21) or 3-year PFS (47.4% vs 35.4%, p=.237) between 50.4 Gy and 41.4 Gy, respectively. In this series of esophageal cancer treated with neoadjuvant chemoradiation with carboplatin/paclitaxel followed by surgical resection, there appears to be no difference in pCR between 41.4 Gy and 50.4 Gy as well as no difference in PFS and OS. Larger, multi-institutional series are needed to validate these results.