[Preoperative evaluation of cancers of the rectum]

The diagnosis of colorectal cancer must be considered in the presence of suggestive symptoms and must be endoscopy. Assessment of operability, including chest x-ray, is completed by CEA determination and x-rays of the colon, looking for a synchronous lesion. Complementary assessments must answer 3 questions: what operation needs to be performed, is any preoperative adjuvant treatment indicated, do any prognostic factors need to be identified before the operation. The treatment of cancer of the colon is now clearly defined; intraoperative hepatic ultrasonography and histological examination of the resection specimen provide all of the necessary data in the majority of the cases. In the presence of a cancer of the rectum, various therapeutic alternatives are available according to the site and stage of the tumour. The complementary assessment includes biopsy to confirm the malignant nature of the lesion, and measurement of the distance of the lower pole from the anal margin (digital rectal examination, endoscopy). A more precise preoperative staging by ultrasonography, computed axial tomography or magnetic resonance is required when the clinician considers that the invasive nature of the lesion justifies preoperative radiotherapy. This precise staging is fully justified in the presence of a small rectal tumour amenable to local resection. Although infiltration of the rectal wall is now very clearly defined, formal identification of metastatic lymphadenopathy still remains hazardous. Finally, the search for distant metastases by invasive and/or expensive techniques is indicated when looking for contraindications to surgery (high-risk patients, surgery for recurrence and metastases). In other cases, the presence of metastases does not contraindicate a palliative colonic resection and intraoperative exploration allows reliable identification of any liver metastasis.