Pathological response to neoadjuvant chemoradiotherapy for oesophageal squamous cell carcinoma: multicentre East Asian and Dutch database comparison

Background Patients with different ethnic and genetic backgrounds may respond differently to anticancer therapies. This study aimed to assess whether patients with oesophageal squamous cell carcinoma (OSCC) treated with neoadjuvant chemoradiotherapy (nCRT) in East Asia had an inferior pathological response compared with patients treated in Northwest Europe. Methods Patients with OSCC who underwent nCRT according to the CROSS regimen (carboplatin and paclitaxel with concurrent 41.4 Gy radiotherapy) followed by oesophagectomy between June 2012 and April 2020 were identified from East Asian and Dutch databases. The primary outcome was pCR, defined as ypT0 N0. Groups were compared using propensity score matching, adjusting for sex, Charlson Co-morbidity Index score, tumour location, cT and cN categories, interval between nCRT and surgery, and number of resected lymph nodes. Results Of 725 patients identified, 133 remained in each group after matching. A pCR was achieved in 37 patients (27.8 per cent) in the Asian database and 58 (43.6 per cent) in the Dutch database (P = 0.010). The rate of ypT1-4 was higher in Asian than Dutch data (66.2 and 49.6 per cent; P = 0.004). The ypN1-3 rate was 44.4 per cent in the Asian and 33.1 per cent in the Dutch data set. Clear margins were achieved in 92.5 per cent of Asian and 95.5 per cent of Dutch patients. Conclusion Regional differences in responses to CROSS nCRT for oesophageal cancer were apparent, the origin of which will need evaluation. Patients with oesophageal squamous cell carcinoma treated with neoadjuvant chemoradiotherapy plus surgery according to the CROSS regimen in East Asia have a lower chance of achieving a pCR in the resection specimen than patients treated in the Netherlands, even after adjusting for well known confounding factors.