Clinical Significance of the Endoscopic Finding in Predicting Complete Tumor Response to Preoperative Chemoradiation Therapy in Rectal Cancer

There are reports that suggest conservative treatment when a tumor shows clinically complete response (CR) after preoperative chemoradiotherapy in rectal cancer. The aim of this study is to investigate the association between endoscopic complete response (E-CR) and pathologic CR (pCR) and to determine the sensitivity and specificity of E-CR and its clinical utility after preoperative chemoradiotherapy in rectal cancer. We analyzed prospectively collected data of patients with middle and lower rectal cancers who underwent preoperative chemoradiotherapy, between January 2010 and January 2015. Nineteen patients (17.9 %) showed E-CR, and 87 patients showed E-non CR. Twenty-three patients (21.7 %) were confirmed to have pCR. E-CR was closely associated with pCR (p < 0.001). E-CR reflected pCR with an accuracy of 88.7 %, sensitivity of 65.2 %, specificity of 95.2 %, PPV of 78.9 %, NPV of 90.8 %, and a p value of < 0.001. E-CR after preoperative chemoradiotherapy in rectal cancer is significantly associated with pCR. However, a wait and see policy should be performed carefully with current endoscopic prediction for pCR to avoid inadequate treatment in patients who show E-CR after preoperative chemoradiotherapy.