CLINICOPATHOLOGICALLY DIAGNOSED RESIDUAL TUMOR AFTER RESECTION FOR COLORECTAL-CANCER - A 20-YEAR PROSPECTIVE-STUDY

Background. A lack of comprehensive information exists on the nature, incidence, and prognostic significance of known residual tumor in colo rectal cancer patients treated by bowel resection. This study aims to provide this information. Methods. A prospective series of 1766 consec utive patients from the Concord Hospital Colorectal Cancer Registry (C oncord, Australia) was used for the analysis. Residual tumor was defin ed as distant metastases diagnosed clinically or pathologically or tum or demonstrated histologically in a line of resection. The pathologic study was highly standardized. Patient follow-up ranged from 6 months to 20.5 years. Survival analysis was by the Kaplan-Meier method. Multi variate models were examined using Cox proportional hazards regression . Results. The prevalence of residual tumor was 20.9% and the median s urvival was 11.6 months. In 4.5%, tumor transection alone occurred, 14 .5% had distant metastases alone, and 1.9% had both. The difference in survival between the first two groups was at marginal statistical sig nificance (P = 0.076). When each of these two groups was compared with the third group, significant differences were noticed (P = 0.001 and P = 0.004, respectively). Five of 14 pathology variables examined had a significant effect on survival using univariate analysis. On multiva riate analysis only tumor transection and distant metastases had signi ficant independent effects. Conclusions. Known residual tumor was comm on in this series: one in five resections. Survival studies show that tumor transection, as defined, is a valid criterion for residual tumor . Survival is significantly reduced when tumor transection and distant metastases both are present. These findings should he heeded when sta ging colorectal cancer and when stratifying patients for postoperative adjuvant therapy.