Endoscopic evaluation of clinical response after preoperative chemoradiotherapy for lower rectal cancer: the significance of endoscopic complete response

The management of rectal cancer is a significant oncologic challenge because rectal cancer has a poor prognosis among the various types of colorectal cancer. There have been several recent reports on a nonoperative approach for advanced lower rectal cancer, and this may be best for local disease control. However, objective evaluation of tumor response after preoperative chemoradiotherapy has not been standardized. The purpose of this study is to evaluate our method of endoscopic evaluation of complete response. This is a retrospective chart review. All patients received a long course of preoperative chemoradiotherapy (5-fluorouracil-based chemotherapy and 45-50.4 Gy) followed by radical surgical resection from May 2005 to March 2012 in The Cancer Institute Hospital of Japanese Foundation for Cancer Research. One hundred fifty-seven patients were reviewed consecutively. Criteria for endoscopic complete response were defined with a focus on the degree of ulcer healing and pit pattern without magnification. Endoscopic CR (E-CR) evaluation with our definitions reflected histopathologic response evaluation with an accuracy of 91.7 %, sensitivity of 27.8 %, specificity of 100 %, positive predictive value (PPV) of 100 %, and negative predictive value (NPV) of 91.4 % (p < 0.001). Our criteria of E-CR led all cases of y-clinical CR (ycCR) to pathological CR. Endoscopic evaluation focused on the degree of ulcer healing, and pit pattern without magnification is useful for judging ycCR.