Early tumor shrinkage and depth of response in patients with metastatic esophageal cancer treated with 2-weekly docetaxel combined with cisplatin plus fluorouracil: an exploratory analysis of the JCOG0807

Background: We herein investigated the association between early tumor shrinkage (ETS) and depth of response (DpR) and clinical outcomes in patients with metastatic esophageal cancer treated with 2-weekly docetaxel combined with cisplatin plus fluorouracil (bDCF) using data from the JCOG0807, a phase I/II trial of bDCF as first-line chemotherapy for metastatic esophageal cancer. Methods: ETS was defined as a percent decrease in the sum of the target lesions’ longest diameter after 8 weeks, whereas DpR was defined as a percentage of the maximal tumor shrinkage during the treatment course. Multivariable analyses were conducted to identify significant prognostic variables in progression-free survival (PFS) and overall survival (OS): one for ETS and covariates, and another for DpR and covariates. Results: Among 53 patients, 35 patients with ETS ≥ 20% (66.0%) had longer PFS (7.5 vs. 3.4 months, hazard ratio [HR]: 0.26, 95% confidence interval [95% CI] 0.14–0.49), OS (13.8 vs. 6.1 months, HR 0.20, 95% CI 0.11–0.39), and PPS (6.4 vs. 2.8 months, HR 0.38, 95% CI 0.20–0.72) than those with ETS < 20%. In addition, 37 patients with DpR ≥ 30% (69.8%) had longer PFS (7.5 vs. 2.9 months, HR 0.17, 95% CI 0.08–0.34), OS (13.8 vs. 6.0 months, HR 0.14, 95% CI 0.07–0.27), and PPS (6.8 vs. 2.8 months, HR 0.30, 95% CI 0.15–0.58) than those with DpR < 30%. Multivariable analyses revealed that each ETS and DpR was an independent factor of longer PFS and OS. Conclusions: ETS and DpR might be associated with clinical outcomes in patients with metastatic esophageal cancer treated with bDCF.