Reappraisal of AJCC Staging System in Colorectal Cancer

ABSTRACT

PURPOSE: The TNM classification for carcinoma of the colon and the rectum provides more detail than other staging systems. This study was performed to evaluate the effectiveness of AJCC staging system (5th ed., 1997) for the colorectal cancer in predicting prognosis. METHODS: We analyzed a data base of 1,233 colorectal cancer patients (MF=673560) who underwent surgery in Asan Medical Center during July 1989-December 1996. Survival analysis was performed between the stages and the subgroups in same stage by using Kaplan-Meier method and log rank test. Borderline subgroup comparison between the stages was performed, also. Significance was assigned to a P value of <0.05. RESULTS: Mean age of the patients was 57 (19-90) years old. Median follow-up period was 42 (6-129) months. The number of patients in each stage were 0 15, I 152, II 390, III 465, IV 199. The 5 year overall & disease free survival rates of each stage were 100%, 100% (in stage 0), 96.4%, 93.6% (in stage I), 82.7%, 82.2% (in stage II), 59.9%, 55.3% (in stage III), and 7.3%, 24.9% (in stage IV), respectively (P=0.000). Subgroup analysis in stage I (T1N0 vs. T2N0) and II (T3N0 vs. T4N0) revealed no differences. However, in stage III, N1 (n=246) group showed better survival than N2 (n=219) group (70.3%, 65.5% vs. 49.2%, 44.6% P=0.000). Borderline survival analysis between stage I and II (T2N0 vs. T3N0) was significantly different (96.6%, 95.7% vs 82.7%, 82.3% P=0.006). However, between stage II and III (T4N0 vs. T1N1), appropriate analysis was impossible due to small number of cases. CONCLUSIONS: AJCC staging system for colorectal cancer was reliable and effective in predicting prognosis. However, substages are needed in stage III.