Neoadjuvant chemotherapy (NAC) followed by surgery is regarded as a standard treatment for Stage II and III resectable thoracic esophageal squamous cell carcinoma (ESCC) in Japan. In general, therapeutic effect of NAC against the primary tumor is estimated microscopically with resected specimen after surgery. Then, this microscopic assessment is validated as surrogating survival. However, as this assessment needs resected specimen, therapeutic effect could not be evaluated before surgery. The aim of this study was to investigate whether therapeutic effects in imaging findings obtained by calculating tumor volume reduction could be a surrogating survival or not.
This retrospective study examined the patients who fulfilled the following criteria; (1) thoracic ESCC, (2) underwent esophagectomy following NAC between January 2011 and December 2015, and (3) clinical Stage II or III. Tumor volume was calculated by multiplying length and thickness in the lateral view of esophagography. The reduction rate of tumor volume was calculated as follow; ( pre NAC tumor volume – post NAC tumor volume) / pre NAC tumor volume . The cut off value of volume reduction ratio was determined as 50%, 60%, and 70% respectively. Patients were divided into an effective group and an ineffective group in each cut off value, and examined relationship with 3-year relapse-free survival (3yRFS). The hazard ratio (HR) for 3yRFS in each cut off value was estimated for selecting optimal cut off surrogating survival.
In total, 93 patients were included in this study. 3yRFS of the effective group / ineffective group and HR of ineffective group for effective group in each cut off were 70.2% / 39.4% (HR = 0.469 [95% CI = 0.253 - 0.868], p = 0.0136) in 50%, 73.5% / 40.3% ( HR = 0.418 [95% CI = 0.216 - 0.809] , p = 0.00752) in 60%, and 80.4% / 42.8% (HR = 0.427 [95% CI = 0.199 - 0.916], p = 0.0243) in 70%.
Therapeutic effect of NAC evaluated by imaging finding was reflected in 3-year relapse free survival. Especially for optimal surrogate of 3yRFS, the optimal cut off point was 60% volume reduction after NAC.
Clinical trial identification
Legal entity responsible for the study
Kanagawa Cancer Center.
Has not received any funding.
T. Hayashi: Personal fee: MDS, Chugai, Ono. T. Yoshikawa: Personal fee: MDS, Chugai, Ono, Taiho. All other authors have declared no conflicts of interest.