ABSTRACT
BACKGROUND: EUS-measured reduction in tumor size after neoadjuvant therapy has previously been correlated with downstaging and improved survival in patients with esophageal cancer. The aim of this study was to determine whether tumor changes measured by EUS correspond to pathologically assessed chemoradiotherapy-induced tumor regression. METHODS: Forty-one patients with esophageal cancer treated with combined modality treatment were studied. After initial EUS, patients completed a cisplatin/carboplatinum, 5-fluorouracil, and radiotherapy regimen and underwent repeat EUS before resection. A positive response on EUS was defined as a 50% reduction in maximal tumor cross-sectional area. Chemoradiotherapy-induced tumor regression was assessed in resection specimens by using a previously defined pathologic scoring system based on the extent of tumor proliferation into adjacent fibrosis. RESULTS: Pathologic tumor regression was present in 23, indeterminate in 5, and minimal or absent in 13 patients. EUS measured a positive response in 20 of 23 (87%) patients with CRT-induced tumor regression and a negative response in 10 of 13 (77%) patients with absent tumor regression (p < 0.001). EUS had a positive predictive value of 80% for pathologic tumor regression. CONCLUSIONS: Measurement of tumor size by EUS is a reliable clinical method for assessing pathologic tumor regression before surgery.
