Evaluating patient outcomes in medical education research: Mission impossible?

摘要

OBJECTIVE:: To examine the clinical utility of improved detection of venous invasion (VI) in patients undergoing potentially curative resection of colorectal cancer. BACKGROUND:: VI is a feature of colorectal cancer (CRC) progression. Elastica staining can be used to improve detection of VI and correspondingly its prediction of patient survival. METHODS:: A single-center, observational study of pathology variables, including detection of VI by staining for elastica, using 631 stage I to III CRC specimens, collected from 1997 to 2009 (176 analyzed retrospectively and 455 analyzed prospectively), was performed. RESULTS:: VI was detected in 56% of patients with CRC. Over a median follow-up period of 73 months, 238 patients died (134 from cancer). On multivariate analysis, VI by elastica staining was associated with a shorter survival duration, independent of other pathology features, in all cases [hazard ratio (HR) = 3.94, 95% confidence interval (CI): 2.33-6.65, P < 0.001] and in node-negative cases (HR = 3.55, 95% CI: 1.81-6.97; P < 0.001). In the absence of elastica-detected VI, with the exception of T stage, no other pathology features were associated with survival time. Therefore, the combination of T stage and VI (TVI) on survival was examined. Five-year cancer mortality could be stratified between 100% and 54% for patients with node-negative tumors and between 100% and 33% for patients with node-positive tumors. In all cases, the TVI had similar predictive value as that of T stage and node status (TNM). In node-negative disease, TVI had superior predictive value. CONCLUSIONS:: The results of the present study have prompted the development of a novel tumor staging system based on TVI. The TVI has clinical utility, especially in node-negative disease, in predicting outcome following curative resection for CRC.