en Radiation Biology Radiation Biology گزارش کوتاه Short Report <p>Background: This study assessed the optimal timing of computed tomography for detection of metastatic disease in locoregional lymph nodes in patients with rectal cancer who have undergone chemoradiotherapy. Materials and Methods: This observational retrospective study was performed in a single institution. All patients with locally advanced rectal cancer treated with chemoradiotherapy, followed by a total mesorectum excision from January 1, 2003 to December 31, 2012, were included. Lymph node metastases evident on preoperative computed tomography were compared with postoperative pathologic lymph node status. Results: The study population consisted of 108 patients: Group A (nodal negative on preoperative computed tomography, n = 52) and Group B (nodal positive on preoperative computed tomography, n = 56). Analysis of the computed tomography scans in Group A revealed a high ability (98.07%) to predict negative lymph nodes, compared to 58.92% for predicting positive lymph nodes in Group B. Conclusion: The results of this study suggest that the optimal timing of computed tomography for assessing lymph nodes after neoadjuvant chemoradiotherapy for rectal cancer is after 6 weeks; this timing might be key for prediction of complete clinical responses. &nbsp;</p> <p></p> Keywords: Computed tomography, chemoradiotherapy, rectum cancer, complete clinical response. 279 285 http://ijrr.com/browse.php?a_code=A-10-1-630&slc_lang=en&sid=1 C.L. Lai 790031947532846009955 790031947532846009955 No Division of Colon and Rectal Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China M.J. Lai 790031947532846009956 790031947532846009956 No Division of Clinical Pathology, Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China C.H. Liu 790031947532846009957 790031947532846009957 No Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China C.C. Wu 790031947532846009958 790031947532846009958 No Division of Colon and Rectal Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China S.W. Jao 790031947532846009959 790031947532846009959 No Division of Colon and Rectal Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China C.W. Hsiao 790031947532846009960 790031947532846009960 Yes Division of Colon and Rectal Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China