Multivariate Regression Analyses Of Prognosis Of Colorectal Cancer After Radical Resection

Objective: Following the economic improvement and life style change, the incidence of colorectal cancer (CRC) has being increased. Now, CRC has became the third common malignant tumor is China. Since the last 10 years, the mortality of CRC hadn't changed a lot, the 5 years survival rate remains at 60% to 70%.Methods: This retrospective study involved 464 consecutive patients with CRC treated by radical surgery from January 1, 1998 to December 31, 2002 in PLA hospital. Patents who had involved synchronism distant metastases before surgery were excluded. The time of the case enrolled in this study is surgical time. Disease-free survival (DFS) was counted as considered as the period of relapse or death. All follow-up ended on December 31, 2006. DFS were estimated by the methods of Kaplan-Meier and log-rank test were used to determine univariate significance .Factors that were deemed of potential importance on univariate analysis were include in the multivariate analysis by the Cox multivariate regression model. Relations between two factors were assessed using the Mann-Whiney test. The performance of the predictive model was evaluated by receiver operating characteristic curves (ROC). Probability values<0.05 were considered statistically significant. Statistical analysis were carried out with SPSS for Windows, version 15.0Result: From January 1, 1998 to December 31, 2002, 464 patients were enrolled in this study, consisting of 300(64.7%) males and 164(35.3%) females. The median age was 58 years (rang 20-90) .The median follow-up from the time of operation was 57.4 months. At last follow-up, 147 patients were relapse or death of disease, compare to 317 patients survival. The cumulative 1-, 3-, 5-years DFS rate was 79%, 70% and 67%, respectively. 1-years DFS of stage I , II A,IIB, IIIA, IIIB, IIIC was 99.00%, 85.62%, 94.63%, 68.18%, 57.91%, 62.23%, respectively. 3-years DFS was 95.52%, 79.35%, 86.51%, 63.48% , 52.15% and 33.39%,respectively. 5-years DFS was 92.77% , 77.48%, 77.25%, 63.48%, 46.15% and 33.39%, respectively.Prognosis factor for DFS: The univariate analysis revealed that the depth of penetration, the number of positive lymph nodes, the number of lymph nodes examined, preoperative serum CEA, lymphovascular invasion and adjuvant chemotherapy were significantly associated with DFS. On multivariate analysis, depth of penetration, the number of positive lymph nodes, elevated preoperative CEA was independent poor predictor of DFS, and the adjuvant chemotherapy was a good one.Recurrence pattern and Recurrence time: The median time of local relapse was 16.9 months, compare with13.3 months of single organ metastasis, and 7.66 months of multiple organ metastasis (p=0.018). Pathologic T stages significantly predicted for early recurrence (p=0.04).Preoperative s-CEA: 413 Patients with preoperative CEA of total 464 patients were enrolled in this study. Using the 5ng/ml as the cutoff values of s-CEA, a significant difference in survival was observed in patients with stage II and III, specially in stage IIA and IIIB. ROC were used to evaluate the prognosis of the s-CEA level by the primary concentration of the s-CEA in stage IIIB of 76 patients, a new cutoff value of 4.1ng/ml was found, which has a sensitivity of 69% and a specificity of 80%.Tumor nodules: Patients of T₃ were classified into three group, negative lymph nodes with tumor nodules (Group A), negative lymph nodes without tumor nodules (Group B), one positive lymph nodes without tumor nodules (Group C). The prognosis was not significantly between Group A and Group C (p=0.415), but it was significantly different between Group B and Group A (p=0.032) and C (p=0.036). From the viewpoint of prognosis, it appears to be more reasonable to regard tumor nodules as lymph node.Conclusion:1, On multivariate analysis, depth of penetration, the number of positive lymph nodes, elevated preoperative CEA and the adjuvant chemotherapy was independent predictor for DFS. 2,The equation for risk factors of prognosis was established.[h (t,xi)] =h0exp(0.485x1+0.509x2+0.37X3-0.57X4) 3 , Preoperative s-CEA may act in dose-dependent manner for poor prognosis. A new cutoff value for prognosis of 4.1ng/ml was found in stage IIIB, which has a sensitivity of 69% and a specificity of 80%. 4, From the viewpoint of prognosis, it appears to be more reasonable toregard "tumor nodules as" lymph node.5, The incidence of more aggressive tumors was higher in younger persons, However, the 5-year survival of younger patients is not worse than the elderly.