Thymidylate Synthase Expression Using Immunohistochemical Staining in Colorectal Cancer

PURPOSE: Thymidylate synthase (TS) is a critical enzyme in the DNA synthesis and an important target of cancer chemotherapeutic agents, such as 5-fluorouracil (5-FU). Recent studies suggest that TS expression is related to the prognosis of various cancers and the mechanism of chmotherapeutic drug resistance. This retrospective study was performed to determine whether TS expressions in primary colorectal tumors influence the overall survival and recurrence for patients with colorectal cancer. METHODS: Intratumoral TS expression was evaluated by immunohistochemical staining using TS-106 monoclonal antibody in primary colorectal cancers of 64 patients who had undergone surgery from July, 1995 to June, 1999. The relationship between TS expressions and patients' survival was evaluated statistically. The median follow-up period was 25.7 months. RESULTS: Overall positive TS expression rate was relatively high (54.7%) in colorectal cancers, and overall disease-free survival rate was significantly higher in the TS positive group (P=0.0204). But there was no statistically significant differences in overall survival rates (P=0.249) and tumor recurrence rates (P=0.732) between positive TS group and negative TS group. CONCLUSIONS: These results suggest that TS expression status in the colorectal cancer tissue is only related to the overall disease-free survival rates, not the overall survival rates and tumor recurrence rates. More objective method and long term follow up study will be required for accurate assessment of clinical importance of TS expression in colorectal cancers.

Clinical Study of Mucinous Colorectal Carcinoma

PURPOSE: The clinical influences of mucinous colorectal carcinomas are still controversial. Some previous reports have suggested that mucinous carcinomas of colorectum affect more young patients, involve the more proximal colon, are more advanced at diagnosis, show increased incidence of local and distant metastasis, and have a worse prognosis than adenocarcinoma. We evaluated the clinicopathological aspect of mucinous colorectal carcinoma. METHODS: A retrospective review of colorectal cancer patients treated between January 1990 and December 1998 was undertaken. Eight-hundred-fifty patients were operated for colorectal cancer during the period, among them seven- hundred-eighty-two patient records were available for this study. Sixty-two patients (7%) could be classified as mucinous carcinoma as defined by more than 50% of mucin- secreting pattern on histological examination. The age and sex distribution, primary location of tumor, modified Dukes' classification at diagnosis, recurrence rates and 5-year survival of mucinous carcinoma patients were compared with those of adenocarcinoma patients. Survival was calculated according to Kaplan-Meyer, and the differences were compared using the log-rank test. RESULTS: The sex ratio of mucinous carcinoma was 2.05: 1, whereas 1.32: 1 in adenocarcinoma. The age distribution of mucinous carcinoma showed orderly 60s (30.7%), 50s (17.7%), 40s (17.7%) similar to adenocarcinoma. The sites of the mucinous carcinoma were 22 (35.5%) in the rectum, 21 (33.9%) in the right colon, 6 (9.7%) in the transverse colon, whereas for adenocarcinoma 250 (37.0%) in the rectum, 137 (20.3%) in the sigmoid colon, 114 (16.9%) in the ascending colon. The stage of primary tumor at diagnosis was as follows: In mucinous carcinoma, 5 stage B1 (8.1%), 13 B2 (21.0%), 33 C2 (53.2%), 11 D (17.7%). In adenocarcinoma, 20 stage A (3.0%), 61 B1 (9.0%), 210 B2 (31.1%), 15 C1 (2.2%), 250 C2 (37.0%), 120 D (17.7%). Three-year and five-year disease free survival rates were similar, but slightly higher in patients with adenocarcinomas. Mean survival time was also similar, 45.5+/-38.1 months in the mucinous carcinoma group and 45.6+/-33.4 months in the adenocarcinoma. Five-year survival was 65.6% and 68.1% in patients with mucinous carcinomas and adenocarcinomas, respectively; but the difference was not statistically significant. The recurrence rates were 41.9% and 22.3% in patients with mucinous carcinoma and adenocarcinoma, respectively with statistical significance (P<0.005). Local recurrence was more frequent in the mucinous carcinoma than in the adenocarcinoma significantly. CONCLUSIONS: Our study suggested that mucinous colorectal carcinoma showed decreased survival, although having no statistical significance and increased recurrence rates with statistical significance compared with those of adenocarcinoma. So, we recommend aggresive surgical treatment and careful follow-up in mucinous colorectal carcinoma.