On predicting clinical response to chemoradiotherapy in esophageal squamous cell carcinoma: additional evaluation by magnetic resonance imaging may help
The current standard treatment options for locally advanced esophageal squamous cell carcinoma (ESCC) include neoadjuvant chemoradiotherapy (CRT) followed by esophagectomy and definitive CRT (1-4). For patients who receive neoadjuvant CRT, pathologic tumor response, including pathologic complete response (pCR) and tumor regression grade, is predictive of patients’ survival (5,6). For patients who receive definitive CRT, clinical complete tumor response has also been shown to associate with patients’ survival (7). However, the clinical tumor response evaluation for locally advanced esophageal cancer is limited by inferior sensitivity and specificity of conventional imaging modalities (8). For example, although endoscopy can evaluate the response of intraluminal esophageal tumor and can confirm the suspicious lesions by biopsy, it could not detect residual tumor deep in muscular layer and adventitia of esophageal wall. The application of computed tomography (CT) to evaluate esophageal tumor response is frequently hampered by consequences of CRT, such as edema, fibrosis, and necrosis. A better clinical tumor response evaluation is warranted to help prognosis prediction in patients of locally advanced ESCC receiving definitive CRT.