An Open-Label Single-Arm Phase II Study of Treatment with Neoadjuvant S-1 Plus Cisplatin for Clinical Stage III...

Two courses of neoadjuvant therapy using S-1 plus cisplatin for clinical stage III esophageal squamous cell carcinoma did not achieve expected response rate according to endoscopic evaluation of primary tumors. Subsequent esophagectomy was safely performed.

In Japan, esophagectomy after two courses of 5-fluorouracil plus cisplatin is regarded a standard strategy for treating stage II or III esophageal squamous cell carcinoma (ESCC). However, 5-fluorouracil plus cisplatin does not benefit cohorts with clinical stage III ESCC, suggesting the need for a more effective regimen.

A single-arm, open-label phase II trial was conducted to evaluate the safety and efficacy of two courses of neoadjuvant chemotherapy using S-1 plus cisplatin (NAC-SP) for clinical stage III ESCC. The primary endpoint was overall response rate as defined by endoscopic evaluation of primary tumors.

We enrolled 26 patients. The completion rate for the two courses of NAC-SP was 61.5%. Grade 3 or higher adverse events were experienced by 38.4% of patients. The treatment response rate according to endoscopic findings, acquired before the second course, was 34.6% and below the expected level (55.0%). The morbidity rate of patients who underwent radical subtotal esophagectomy (96.2%) was 32.0%. Repeat surgery was unnecessary, and surgery-associated deaths did not occur. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 84.6% and 92.2%, respectively.

We demonstrate safety of NAC-SP, but not its efficacy, for patients with clinical stage III ESCC. Subsequent esophagectomy was safely performed.