Early tumor shrinkage (ETS) and deepness of response (DpR) in patients with metastatic esophageal cancer receiving a first-line treatment with DCF: Exploratory analysis of the JCOG0807.

Abstract

183 Background: ETS and DpR have been recognized as favorable prognostic factors of metastatic colorectal cancer. However, the effect of tumor shrinkage on clinical outcomes has not yet been reported for metastatic esophageal cancer (mEC). The purpose of the present study is to determine the associations of ETS and DpR with progression-free survival (PFS), post-progression survival (PPS), and overall survival (OS) in patients (pts) with mEC. Methods: This exploratory analysis included 53 pts, who received triplet chemotherapy with docetaxel (D) plus CF (cisplatin plus 5-fluorouracil) (DCF) as a first-line treatment during the JCOG0807. ETS after 8 weeks was defined as a relative change of 20% in the sum of the longest diameters of target lesions compared with baseline. DpR was defined as a relative change in the sum of the longest diameters of target lesions at the nadir compared with baseline. The cutoff level of DpR was 30%. PPS was calculated as follows: PPS = OS - PFS. Univariate and multivariate analysis using Cox proportional hazard model was performed to identify a predictor of PFS and OS. Results: Thirty-five of the 53 pts achieved ETS ≥ 20% after 8 weeks. Thirty-seven of the 53 pts achieved DpR ≥ 30%. Pts with ETS ≥ 20% showed longer PFS (7.5 vs. 3.4 months (M), p < 0.001, HR: 0.26, 95% CI 0.14–0.49), longer OS (13.8 vs. 6.1 M, p < 0.001, HR 0.20, 95% CI 0.11–0.39), and longer PPS (6.4 vs. 2.8 M, p = 0.002, HR 0.38, 95% CI 0.20–0.72). Further, pts with DpR ≥ 30% showed longer PFS (7.5 vs. 2.9 M, p < 0.001, HR 0.17, 95% CI 0.08–0.34), longer OS (13.8 vs. 6.0 M, p < 0.001, HR 0.14, 95% CI 0.07–0.27), and longer PPS (6.8 vs. 2.8 M, p < 0.001, HR 0.30, 95% CI 0.15–0.57). Multivariate analysis, including the following additional prognostic variables: age, ECOG PS, the lactate dehydrogenase level, and the number of organs with metastases revealed that ETS ≥ 20% and DpR ≥ 30% were predictors of PFS and OS. Conclusions: ETS and DpR were associated with longer PFS, OS, and PPS. They were also strongly prognostic of PFS and OS in mEC pts treated with DCF. These findings support the treatment strategy involving the highly effective triplet chemotherapy as a first-line treatment of mEC. Clinical trial information: UMIN000001737.