Ki67 labelling index and performance status are predictive factors of response to concomitant radiochemotherapy (RCT) in esophageal cancer

Abstract

15119 Background: In oesophageal cancer, preoperative RCT allows a prolonged survival for patients achieving a complete pathological response at time of surgery. However, predictive factors for complete response to RCT are not well known. The aim of this retrospective study was to identify clinical and histopathological factors predictive of complete endoscopic response (CER) in patients treated by RCT before surgery or as exclusive treatment for esophagus cancer. Methods: from 2000 september to 2006 march, 56 patients with esophagus cancer (35 squamous cell carcinoma (SCC), 20 adenocarcinoma (ADK), 1 undifferentiated) were treated by RCT (45–50 grays /25 fractions / 5 weeks and 2 courses of 5FU-CDDP at weeks 1 and 5). 16 patients subsequently underwent oesophageal resection. Endoscopy with biopsies was performed 3 weeks after the end of RCT. Clinical, biological, radiological and pathological (including EGFR, p53 and Ki67 immunostaining) parameters were included in univariate and multivariate analysis to determine predictive factors for CER. Results: CER was observed in 31 out of 54 appraisable patients (57.4%). In both univariate and multivariate analysis, 2 factors were predictive of complete endoscopic response: good performance status (PS 0 vs 1–2: OR = 15.75 - p=0.01) and higher expression of Ki67 (>=18 vs <18: OR = 4.46 - p=0.04).A pCR was seen in 7 (44%) of the 16 operated patients. Positive predictive value of endoscopy for pCR was 87.5% (IC95%: 47.4–99.7%), and negative predictive value was 100% (IC95%: 68.7–100%). Predictive factors of pCR were: a complete endoscopic response (p<0.01), a complete CT-scan response (p=0.03) and a good performance status (p=0.04). Median survival in all 56 patients was 40 months. Pejorative prognostic variables for survival in multivariate analysis were adenocarcinoma histology (RR=3.11; p=0.03), and performance status (RR=4.79; p=0.04). Conclusions: In our study, a good performance status and surexpression of Ki67 were independent predictive factors for complete endoscopic response after RCT. The 2 prognostic factors for survival are histologic type and performance status. No significant financial relationships to disclose.