Preoperative staging of rectal cancer

With the widespread introduction of preoperative radiotherapy for rectal ca ncer and the development of transanal endoscopic microsurgery for selected early lesions, preoperative radiological staging of these tumours has taken on increasing importance. This study is a systematic review to evaluate co mputed tomography (CT), endorectal sonography (ES) and magnetic resonance i maging (MRI) as preoperative staging modalities in rectal cancer. A Medline -based search identifying studies using CT, ES, or MRI in preoperative stag ing of rectal cancer between 1980 and 1998 was undertaken. The list of pape rs was supplemented by extensive cross-checking of citation lists. Studies were included if they met predetermined criteria. Data from the accepted st udies were entered into pooled tables comparing radiological and pathologic al staging results for each modality both in determining bowel wall penetra tion and involvement of lymph nodes. Accuracy, sensitivity, specificity, po sitive predictive value, negative predictive value, positive likelihood rat io and negative likelihood ratio were determined for the pooled results. Ei ghty-three studies from 78 papers including 4897 patients met the inclusion criteria. In determining the wall penetration of the tumour the values for sensitivity for CT, ES, MRI and MRI with endorectal coil were 78%, 93%, 86 % and 89%; for specificity 63%, 78%, 77% and 79%; and for accuracy 73%, 87% , 82% and 84%, respectively. In determining the nodal involvement by tumour the sensitivity values for CT, ES, MRI and MRI with endorectal coil 52%, 7 1%, 65% and 82%; for specificity 78%, 76%, 80% and 83%; and for accuracy 66 %, 74%, 74% and 82%, respectively. MRI with an endorectal coil is the singl e investigation that most accurately predicts pathological stage in rectal cancer.