The CR-POSSUM model provided an accurate predictor of operative mortality. External validation is required in hospitals different from those in which the model was developed.

Using prognostic models, it was possible to develop a risk-stratification index that accurately predicted survival in patients presenting with malignant large bowel obstruction. The methodology and model for risk adjusted survival can set the reference point for more accurate and reliable comparative analysis and be used as an adjunct to the process of informed consent.

The results of the study suggest that the minimum number of lymph nodes harvested in colorectal cancer surgery cannot be set at a fixed value. The lymph node harvest model provides a simple tool to the frontline clinician for comparing standards between multidisciplinary bowel cancer teams.

Overall lymph node harvest, in this unit, varied according to the reporting pathologist but not operating surgeon. As lymph node harvest increased to 15 per patient, the probability of identifying a metastatic node increased.

Objective To study circumferential margin involvement (CMI) in patients undergoing restorative, compared with nonrestorative, surgery for rectal cancer.Data source Descriptive multicentre study, using routinely collected clinical data from the Association of Coloproctology of Great Britain and Ireland (ACPGBI) Bowel Cancer Audit database. The study encompassed 1403 newly diagnosed patients with rectal cancer undergoing either restorative (anterior resection (AR)), or nonrestorative (abdominoperineal excision of rectum (APER) or Hartmann's procedure), surgery. Operations were carried out in 39 hospitals during a variable period between April 1999 to March 2002. A logistic regression analysis was used to control for variables associated with circumferential margin involvement.Results One thousand and thirty-six patients satisfied the inclusion criteria. The average CMI was 12.5% (range 0-33.3% between hospitals). CMI for anterior resection was 7.5% (n ¼ 629) compared with a CMI of 16.7% for APER (n ¼ 306) and a CMI of 31.7% for Hartmann's procedure (n ¼ 101); P £ 0.001. CMI for patients undergoing curative surgery was 7.1% (423 anterior resections, CMI 3.8% (n ¼ 16); 181 APER, CMI 13.3% (n ¼ 24); 29 Hartmann's procedure, CMI 17.2%). On multivariate analysis, having controlled for Dukes' stage and operative intent, the CMI was significantly different between APER and AR (odds ratio 3.3, 95%CI 2.0-5.4), but less so between Hartmann's procedure and AR (odds ratio 2.2, 95%CI 1.1-4.2).Conclusions APER is associated with a significantly higher CMI than anterior resection. Attention to surgical technique, with a wide perineal dissection and the use of pre-operative adjuvant therapy, may reduce CMI in patients undergoing APER.