INDEPENDENTLY PREDICTIVE PROGNOSTIC VARIABLES AFTER RESECTION FOR COLORECTAL CARCINOMA

Abstract

Clinical variables such as surgical morbidity, comorbidity and follow-up have been claimed to influence ultimate survival in patients who have resection for colorectal cancer. It is unclear whether the effect of clinical covariates is confounding or independent. We have attempted to build a comprehensive model, which is capable of testing the dependence and importance of prognostic factors. A consecutive series of patients admitted between 1970 and 1988 and followed until 1992 had data recorded about presentation, pathology, hospitalization, aftercare and long-term outcome. The patients were also divided into two approximately equal groups that were cared for by one and seven surgeons, respectively. Clinical and pathological covariates were built into a Cox (multivariate) proportional hazard model of crude survival. This was achieved with the SPSS advanced statistical package version 6.1. Comparison between groups was then performed of clinical and pathological factors and subsequent cancer management. There were 207 patients whose average age was 75 years, median survival was 43 months and operative mortality was 4%. The Cox model was robust. Covariates that had independent survival effects were pathological stage (P = 0.0000), grade (P = 0.014), age (P = 0.018), heart disease (P = 0.001), and group (P = 0.0008). Some of the dependent variables were symptoms, type of surgery, complications and length of stay. The groups, however, were well matched for age, stage, substage and comorbidity. Furthermore there were no substantial differences in mortality, complications or follow-up frequency. There was a significant survival difference (P = 0.0003) between groups, which was restricted to patients who were in clinicopathological stages B and C. Within stages B and C there was a significant (P = 0.008) survival difference between patients who were or were not treated for recurrent disease. Diagnosis of recurrence was pursued more aggressively (P < 0.01), and decisions to treat recurrent disease were made more frequently in group 1 (P = 0.0002). Pathology, comorbidity and management of recurrence all have a significant independent effect upon crude survival after colorectal carcinoma resection.