Prognostic and predictive value of the thymidylate synthase expression in patients with non-metastatic colorectal cancer.

AIMS: To assess the value of thymidylate synthase (TS) expression as a predictive factor in the efficacy of adjuvant chemotherapy in colorectal cancer, as well as its independent prognostic value for survival. METHODS: We studied 114 high risk colorectal carcinoma patients (high risk stage II and stage III), distributed in two treatment groups: surgery alone (61 patients) or surgery followed by 5-FU-based chemotherapy (53 patients). TS protein expression in the tumour tissue was assessed by immunohistochemistry. RESULTS: In the surgery alone subgroup, overall survival (OS) at 5 years were 77.5% for the patients with low TS expression, against 57.7% for the patients with high TS expression (p=0.006). Among patients with low TS, there was no difference in OS as a result of whether adjuvant chemotherapy was carried out or not (65.8 vs 77.5%, p=0.29). Among the patients with high TS, there was a significant gain in OS in favor of chemotherapy (87.8 vs 57.7%, p=0.04). Analyzing the complete sample, TS expression was not shown as an independent prognostic factor for survival in the multivariate analysis. CONCLUSIONS: The immunohistochemical TS expression may be used for selecting patients for better adjuvant chemotherapy protocols. In this sample, TS expression was not an independent prognostic factor for survival.     

Predictive role of thymidylate synthase, dihydropyrimidine dehydrogenase and thymidine phosphorylase expression in colorectal cancer patients receiving adjuvant 5-fluorouracil

OBJECTIVE: The combined assessment of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD) and thymidine phosphorylase (TP) gene expressions in metastatic colorectal cancer has been reported to be able to predict the efficacy of fluoropyrimidine-based chemotherapy. In order to evaluate the prognostic role in the adjuvant setting, we investigated the TS, DPD and TP expression in primary tumors of colorectal cancer patients treated with 5-fluorouracil (5-FU). METHODS: TS, DPD and TP expression levels were determined by immunohistochemistry in paraffin-embedded primary tumor tissues from 62 patients with Dukes' stage B and C colorectal cancers who underwent surgery and received adjuvant systemic chemotherapy with 5-FU. The median follow-up was 90 months (range 17-127). RESULTS: Dukes' stage C cancer and high TS expression were independent markers of poor prognosis for disease-free survival (DFS; p = 0.0009 and p = 0.007, respectively) and overall survival (OS; p = 0.0005 and p = 0.011, respectively). By multivariate analysis, patients with high DPD expression had significantly shorter DFS (p = 0.007) and OS (p = 0.005) compared to patients with low DPD expression. In the combined analysis of 2 markers, patients with low TS and low DPD had the best outcome in terms of DFS (p = 0.007) and OS (p = 0.03). The analysis of all 3 proteins showed that the patients with low expression of all 3 markers had significantly longer DFS (p = 0.04) and OS (p = 0.01) than patients with a high value of any one of the protein expressions. However, the joint analysis of 3 markers (group with TS-/DPD-/TP-) could not identify a subgroup of patients with a better prognosis compared to the analysis of 2 markers (group with TS-/DPD-). The analysis of Dukes' stage C cancer patients confirmed a significant benefit in terms of DFS and OS (p = 0.001 and p = 0.006, respectively) when all 3 markers had low expression. We also found a positive significant correlation between TS and TP protein expression (p = 0.033). CONCLUSIONS: This retrospective investigation suggests that the combined assessment of TS and DPD may be useful to evaluate the prognosis of patients with Dukes' B and C colon carcinoma receiving 5-FU adjuvant chemotherapy. The role of TP as a predictor for 5-FU-based therapy needs further investigations.     

Marked variation of thymidylate synthase and folylpolyglutamate synthetase gene expression in human colorectal tumors

Patients with advanced colorectal cancer are currently being treated with 5-fluorouracil (5-FU)-based chemotherapy. A growing number of patients with resectable disease receive adjuvant therapy with 5-FU/levamisole (LEV) or 5-FU/folinic acid (LV). However, many patients still fail on these treatments, due to occurrence of natural or acquired tumor resistance. Among clinically relevant mechanisms of resistance to fluoropyrimidines, increased expression of thymidylate synthase (TS) has been emphasized. Another potentially relevant mechanism involves a decrease in folylpolyglutamate synthetase (FPGS) expression. To establish the value of these genes as prognostic factors and predictors of the outcome of 5-FU-based chemotherapy in colorectal cancer, we measured their expression in colorectal tumors from patients undergoing surgery and postoperative chemotherapy and compared it with that in normal colonic mucosa. This was done by a semi quantitative, nonradioisotopic polymerase chain reaction (PCR) method using beta-actin as an internal standard and expressed as a TS/beta-actin or a FPGS/beta-actin mRNA ratio. In tumor samples from 21 colorectal cancer patients, TS gene expression varied 118-fold. The median TS/beta-actin ratio was, in fact, 41.36 x 10(-3) (range 2.49 x 10(-3) to 294.54 x 10(-3)). Little variation in TS gene expression was observed in corresponding normal colic mucosa; the TS/beta-actin gene ratio was lower (median 26.16 x 10(-3); range 8.49 x 10(-3) to 69.49 x 10(-3)). Among tumor explants from 20 patients, FPGS expression varied over 161-fold. A similar marked variation was also observed in normal colonic mucosal samples (over 185-fold). Overall and disease-free survival data suggest an inverse association between the level of tumor TS and FPGS expression and clinical prognosis. The availability of this sensitive and accurate assay for gene expression should now make it possible to extend these laboratory/clinical correlations to larger populations.     

Tumor dihydropyrimidine dehydrogenase in stage II and III colorectal cancer: low level expression is a beneficial marker in oral-adjuvant chemotherapy, but is also a predictor for poor prognosis in patients treated with curative surgery alone

The aim of this study was to evaluate the prognostic significance of tumor dihydropyrimidine dehydroganase (DPD) in curatively resected colorectal cancer patients who received or did not receive oral 5-FU based-adjuvant chemotherapy. Among 182 patients with stage II-III colorectal cancers, 89 patients (adjuvant chemotherapy group) received oral 5-FU based-adjuvant chemotherapy, and 93 patients (surgery alone group) did not receive 5-FU. DPD expressions in the tumors and in the normal colonic mucosa were measured by enzyme-linked immunosorbent assays. The mean DPD expression of the tumors was significantly lower than that of the normal mucosa (54.4 +/- 40.4 versus 72.3 +/- 23.3 Unit/mg protein, P < 0.01). For survival analyses, we designated the cut-off value of tumor DPD as its median value (46.3). In the adjuvant chemotherapy group, high tumor DPD levels were associated with poor survival (HR, 5.24; P = 0.03). In the surgery alone group, high tumor DPD levels were associated with better survival (HR, 0.32; P = 0.02). In conclusion, tumor DPD level is an efficacious marker in oral 5-FU based-adjuvant chemotherapy for colorectal cancer; however, low tumor DPD predicts reduced survival in patients treated with curative surgery alone.     

Topoisomerase-I, thymidylate synthase primary tumour expression and clinical efficacy of 5-FU/CPT-11 chemotherapy in advanced colorectal cancer patients

While several studies have reported that thymidylate synthase (TS) tumour expression can be a reliable predictive marker of clinical response to 5-Fluorouracil (5-FU) for advanced colorectal cancer patients, only a few studies that searched for predictive factors of irinotecan (CPT-11) clinical response are available. The aim of the present study has been to verify the predictive value of immunohistochemical topoisomerase-I (Topo-I) and TS primary tumour expression in a consecutive series of 62 advanced colorectal cancer patients that received a first line 5-FU/CPT-11 chemotherapy. TS and Topo-I immunostaining was observed in 76% and 43% of tumours, respectively, resulting in a significant relationship within each tumour (r=0.365, p<0.004). Patients with different TS tumour expression showed a similar percentage of Objective Clinical Response, OR (40% vs. 28% of OR in low and high TS-expressing tumours, respectively, p=ns); also, patients with different Topo-I tumour expression did not show a different probability of OR (39% vs. 29% of OR in high and low Topo-I expressing tumours, respectively; p=ns).The tumour expression of these 2 biomarkers also did not impact on time to progression and overall survival of patients. Furthermore, the combined analysis of TS and Topo-I tumour status did not permit to individualize subgroups of patients with different probability of OR. With multivariate analysis, only patient Performance Status significantly impacted on OS (Hazard ratio 4.87; p=0.02) of these patients. We can conclude that high TS tumour expression seems not to preclude a clinical activity for 5-FU/CPT-11 polichemotherapy in advanced colorectal cancer patients; furthermore, clinical response and prognosis of colorectal cancer patients treated with 5-FU/CPT-11 regimen do not differ in tumours with different TS or Topo-I expression.     

Tumor dihydropyrimidine dehydrogenase expression is a useful marker in adjuvant therapy with oral fluoropyrimidines after curative resection of colorectal cancer

Purpose Dihydropyrimidine dehydrogenase (DPD) is the rate-limiting enzyme of 5-fluoropyrimidine (5-FU) catabolism. We examined whether tumor DPD expression is an effective marker in adjuvant therapy with oral fluoropyrimidines after curative resection of colorectal cancer.Methods We studied 89 patients with stage II–III colorectal cancers who had undergone curative resections and received oral 5-FU-based adjuvant chemotherapy. The levels of DPD expression in tumor and normal colonic mucosa were measured by an enzyme-linked immunosorbent assay. In 53 tumor samples, DPD enzymatic activity was also analyzed in order to evaluate the relationship between DPD expression and enzymatic activity.Results DPD expression significantly correlated with DPD enzymatic activity in these 53 tumors (r=0.56; P<0.001). DPD expression in the tumors was significantly lower than in normal mucosa (47.1±30.8 and 56.4±18.5 U/mg protein, respectively; P<0.05). We designated the cut-off value of tumor DPD as its median value (46.0 U/mg protein). Patients with low DPD expression had longer disease-free intervals than those with high DPD expression according to univariate analysis (P=0.026). In a multivariate analysis, low DPD expression was significantly and independently associated with better survival.Conclusions Tumor DPD expression is a useful marker for use with adjuvant chemotherapy with oral fluoropyrimidines after curative resection of colorectal cancer.     

Thymidylate synthase and dihydropyrimidine dehydrogenase activity in a metastatic liver tumor from colorectal cancer

The value of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) activity in metastatic liver tumor from colorectal cancer as predictive parameters for hepatic artery infusion (HAI) chemotherapy with 5-FU was investigated. Thirteen patients with metachronous liver metastases underwent hepatic resection and primary site colectomy. We measured TS and DPD activity in normal colonic mucosa, primary colon tumor, and metastatic liver tumor in these patients. The TS (pmol/g-tissue) of primary tumor, metastatic tumor, and normal colonic mucosa was 6.6 +/- 1.40 (mean +/- SE), 3.2 +/- 0.83 and 2.5 +/- 0.83 respectively. The DPD (pmol/min/mg/protein) of primary tumor, metastatic tumor, and normal colonic mucosa was 31.7 +/- 5.49, 82.1 +/- 12.5 and 50.6 +/- 8.46, respectively. There was significant relationship between DPD activity level and recurrence. It is suggested that 5-FU catabolism in metastatic liver tumor was increased, and DPD activity may be a valuable predictive marker for tumor response to HAI therapy.     

Predictive value of thymidylate synthase expression in resected metastases of colorectal cancer

Recent investigations have focused on the prognostic value of thymidylate synthase (TS) assessment in metastases of colorectal carcinoma (CRC). In order to evaluate the prognostic impact of TS expression after resection of metastases of colorectal cancer followed by systemic adjuvant chemotherapy, we performed an immunohistochemical characterisation of TS in the primary tumours and in the corresponding radically resected hepatic and pulmonary metastases. An additional objective was to compare the levels of TS in primary and metastatic disease. TS expression was assessed by immunohistochemistry using the monoclonal antibody TS 106. The study population consisted of 60 patients: 48 underwent liver and 12 lung resection. All of them received adjuvant chemotherapy after metastasectomy according to the Mayo Clinic schedule. In the 49 evaluable primary tumours, TS score was high in 53% and low in 47% of patients, while in the 60 metastatic samples TS immunostaining was high in 33% and low in 67%. There was a significantly smaller number of high TS expressors in metastatic than in primary tumours (P<0.04). No correlation was observed between TS expression and the site of the metastasis. TS status did not significantly correlate with the median disease-free interval (DFI) after metastasectomy, although this parameter was longer for patients with low TS immunoreactivity in the resected metastases than for those with high TS lesions (19.6 versus 13.8 months). Patients with high TS levels, however, had a significantly shorter median overall survival (OS) (27.6 months) than those with low TS expression (36.3 months) (P<0.008). TS status in the resected metastases confirmed its independent prognostic value in the multivariate analysis and was the only prognostic marker of OS in the subgroup of patients with resected liver metastases. These results suggest that high TS levels in resected metastases of colorectal cancer are associated with a poor outcome after surgery and 5-FU adjuvant therapy; therefore, a prospective assessment of TS levels in resected colorectal metastases could be useful to define which patients will most likely benefit from 5-FU adjuvant therapy after metastasectomy. Chemotherapeutic agents that target TS may not be the appropriate adjuvant treatment after metastasectomy for patients with a high TS expression in the resected metastases of colorectal cancer.     

TS和MMR联合检测在结直肠癌预后判断中的作用

目的:对133例结直肠癌患者临床病例资料进行回顾性分析,分析胸苷酸合成酶(thymidylate synthase,TS)蛋白与错配修复(mismatch repair,MMR)状态联合检测与结直肠癌患者临床病理特征及预后之间的关系.方法:免疫组化测定TS和MMR(MLH-1/MSH-2)蛋白表达.根据TS蛋白和MMR状态差异进行相应的配对组合,将纳入患者分为四组:TS蛋白高表达/MMR蛋白高表达(HtHm)组、TS蛋白低表达/MMR蛋白高表达(LtHm)组、TS蛋白低表达/MMR蛋白低表达(LtLm)组、TS蛋白高表达/MMR蛋白低表达(HtLm)组.分析TS和MMR联合检测与患者临床病理因素及预后的关系.结果:TS和MMR联合检测生存分析显示,LtHm组患者(39例)的3年生存率为69.2%,HtLm(20例)组患者的3年生存率为40.0%,两组总体生存率具有统计学差异(P=0.012),该差异在术后辅助化疗患者中仍存在(P=0.011).结论:辅助化疗组患者中LtHm组总体生存率显著高于HtLm组,LtLm组患者较HtHm组患者更易从氟尿嘧啶类药物辅助化疗中获益.     

Thymidylate synthase expression as a predictor of the prognosis of curatively resected colon carcinoma in patients registered in an adjuvant immunochemotherapy clinical trial

The expression levels of thymidylate synthase (TS) affect the sensitivity of tumor cells to fluorinated pyrimidine cytotoxic agents and determine the response of patients with colorectal cancer to fluorinated-pyrimidine-based chemotherapy. The correlation between the expression of TS and the prognosis of patients with colorectal cancer was examined in a prospective study. Evaluation of biomarkers including TS expression was performed using tumor specimens from 229 colorectal cancer patients. Immunohistochemical analysis of TS expression was performed using an antibody raised against a C-terminal epitope (D186-V313) of the human TS. The intensity of TS staining and the expression of other biomarkers were blindly scored. The five-year survival rates were 63.4% and 85.6% among patients with high and low intratumoral TS expressions, respectively (p=0.0007). Similarly, the disease-free survival (DFS) rate was 51.2% and 80.3% in the high and low TS expression groups, respectively (p=0.0004). In a subset analysis of Dukes' stage C patients, the survival and DFS rates were 44.0% and 40.0% in the high TS expression group, and 73.5% and 67.4% in the low TS expression group, respectively. Significant differences were observed in both survival (p=0.0048) and DFS (p=0.0054) rates. No significant correlation was observed between the expression of other biomarkers and prognosis. Significantly poorer prognosis of curatively resected colon cancer in patients with high TS expression levels in tumor tissue was confirmed by a double-blind prospective study conducted on samples obtained from patients enrolled in an adjuvant immunochemotherapy randomized clinical trial.     

Single nucleotide polymorphism in the 5' tandem repeat sequences of thymidylate synthase gene predicts for response to fluorouracil-based chemotherapy in advanced colorectal cancer patients

Thymidylate synthase (TS) is the primary target of 5-fluorouracil (5-FU). A VNTR polymorphism in the TS promoter region is associated with the efficacy of 5-FU-based chemotherapy in colorectal cancer. A common G>C SNP at the 12th nucleotide of the second repeat in the TS*3 alleles has been recently described. The combination of SNP and VNTR allows the definition of 3 TS alleles: *2, *3G and *3C. The aim of our study was to evaluate the predictive value of clinical response and survival of these new defined TS alleles. TS genotypes of 89 patients diagnosed with metastatic colorectal cancer and undergoing 5-FU-based chemotherapy were carried out. The clinical outcome was evaluated according to the genotype (high expression genotype: *2R/*3G; *3C/*3G; *3G/*3G; and low expression genotype: *2R/*2R; *2R/*3C; *3C/*3C. A higher overall response was observed in the group of patients with a low expression genotype (p = 0.035). The probability of achieving a clinical response of patients with a low expression-related genotype was 2.9 higher than that of the other group (95% CI = 1.03-5.6, p = 0.04). The median time to progression was 12 months and 9 months in the low and high expression groups, respectively (p = 0.07, log rank test). Overall survival was significantly longer in the low expression group. In this group the median OS was not achieved at 50 months of follow-up in contrast to the 20 months observed in the high expression group (p = 0.03). TS genotype was an independent predictor of progression-free and overall survival in the Cox regression models after adjustment to the other clinical variables. The selection of patients who are likely to respond to 5-FU therapy may be considerably improved if the TS genotype were to include both the VNTR and the SNP located within the promoter region of the gene.     

Immunohistochemical evaluation of thymidylate synthase (TS) and p16INK4a in advanced colorectal cancer: implication of TS expression in 5-FU-based adjuvant chemotherapy

BACKGROUND: Our previous analyses on the expression of thymidylate synthase (TS) and p16(INK4a) in colorectal cancer patients administered 5-fluorouracil (5-FU) pre-operatively demonstrated that a high level of TS expression was a predictor of 5-FU resistance, and that the combination of a low level of TS expression and induction of p16(INK4a) after chemotherapy implicated chemosensitivity. The present study aimed to assess the relationship between the biological behavior of advanced colorectal cancer treated post-operatively by 5-FU-based chemotherapy and the expression of TS and p16(INK4a) in primary tumors. METHODS: Formalin-fixed, paraffin-embedded specimens from 132 colorectal cancers (Dukes' B, 36 cases; Dukes' C, 60 cases; and Dukes' D, 36 cases) treated by 5-FU post-operatively were immunostained for TS and p16(INK4a). Antigenicities were suitably retrieved. RESULTS: Primary tumors expressing high levels of TS in the Dukes' C group showed a significantly shorter recurrence-free interval (RFI) (P = 0.0002). The overall survival (OS) was shorter in high TS expressors than in low TS expressors (P = 0.001). A high level of TS expression also correlated with advanced Dukes' staging and the severity of nodal metastasis (Dukes' B versus Dukes' D, P = 0.001; Dukes' C versus Dukes' D, P = 0.008; N0 versus N2, P = 0.002; N1 versus N2, P = 0.03). p16(INK4a) expression was not correlated with the prognosis or clinicopathological features. CONCLUSIONS: Appropriate immunohistochemical evaluation is essentially important. We suggest that, in the Dukes' C group, a 5-FU-based regimen can be chosen as a first-line chemotherapy for low TS expressors. TS-high cancer should be treated with anti-cancer agents acting through different mechanisms. Further research should be conducted on applying TS immunostaining to the treatment strategy.     

Clinical significant of semiquantificating DNA topoisomerase- I mRNA in colorectal cancer

PURPOSE: To examine the clinical significance of determining the expression levels of DNA topoisomerase- I (topo-I) mRNA of colorectal cancer. METHODS: The relative expression levels of topo-I mRNA in primary colorectal cancer and adjacent normal mucosa were semiquantificated by the RT-PCR method. The relative expression of thymidylate synthase (TS) mRNA of the primary lesions was also examined. RESULTS: The topo- I mRNA expression was higher in the tumorous tissue than in the normal mucosa (n=22, p<0.01). The topo- I mRNA expression did not significantly correlate with 9 clinicopathological variables examined (n=22). In patients who received irinotecan hydrochloride (CPT-11) following the failure of 5-fluorouracil-based treatment, the topoI mRNA expression did not differ nor correlate with the response to CPT-11 (PR, n=14; SD, n=11; PR; n=24) (p=0.91). In these patients, there was no relationship between the topo I mRNA expression and the TS mRNA expression (p=0.22, r=0.18). In addition, the efficacy of CPT-11 did not correlate with combinations subdivided according to the expression levels of topo- I mRNA and TS mRNA. CONCLUSIONS: Determination of topo- I mRNA levels of primary colorectal cancer may not be useful for predicting the efficacy of CPT-11 treatment alone or in combination with TS mRNA levels.     

A Combined Analysis of Mismatch Repair Status and Thymidylate Synthase Expression in Stage II and III Colon Cancer

BackgroundColon cancer with mismatch repair deficiency and low TS expression has been associated with an improved prognosis. Data also indicate that MMR proficient colon cancer with high TS expression has a better response to adjuvant 5-FU-based chemotherapy. This study evaluates if a combined analysis of MMR status and TS expression in colon cancer can add prognostic value and better predict response to adjuvant 5-FU-based chemotherapy. The potential relationship between MMR status and TS expression is also investigated.Patients and MethodsThis study includes a subgroup of 716 patients with colon cancer out of 2224 stage II and stage III colorectal cancer patients enrolled in Nordic trials randomized to surgery alone or surgery plus adjuvant 5-FU-based chemotherapy. After immunohistochemical analysis of tumor MMR status and TS expression the patients were divided into 4 groups.ResultsThere was a nonsignificant difference in overall survival between group 1 (patients with deficient MMR tumors with low TS) and group 4 (patients with proficient MMR tumors expressing high TS). When comparing group 1 and group 4 patients treated with surgery alone a trend to better overall survival was found in group 1, P = .06. In group 4, stage III patients had a significantly improved survival when receiving adjuvant 5-FU-based chemotherapy compared with surgery alone, P = .01. No relationship was found between MMR status and TS expression.ConclusionsA combined instead of a single marker analysis of MMR status and TS expression can improve the prediction of response to 5-FU-based chemotherapy in stage III colon cancer.     

Thymidylate synthase expression predicts the response to 5-fluorouracil-based adjuvant therapy in pancreatic cancer.

PURPOSE: Thymidylate synthase (TS) is the target enzyme for 5-fluorouracil (5-FU), and TS expression may determine clinical response and survival after therapy with 5-FU in colorectal cancer. 5-FU is also widely used in the adjuvant therapy of pancreatic cancer. Therefore, we explored the hypothesis that TS expression was associated with patient prognosis and the response to adjuvant therapy in pancreatic cancer. EXPERIMENTAL DESIGN: Cylindrical tissue cores from a large retrospective, nonrandomized series covering 132 resected patients were used to build a pancreatic cancer tissue microarray. TS expression was determined using immunohistochemistry. RESULTS: High intratumoral TS expression and low intratumoral TS expression were present in 83 of 132 (63%) and 49 of 132 (37%) tumors, respectively. Median survival among patients with low intratumoral TS expression (18 months) was longer than that among patients with high TS expression (12 months). In multivariate analysis, more advanced pathological stage [risk ratio (RR) = 1.70; P = 0.015], poorly differentiated histology (RR = 1.71; P = 0.015), management with adjuvant therapy (RR = 0.49; P = 0.011), and high TS expression [RR = 1.66; 95% confidence interval (CI) = 1.05-2.63; P = 0.029] were independent predictors of mortality. The risk of death was significantly reduced by any adjuvant therapy (RR = 0.40; 95% CI = 0.18-0.90; P = 0.001) among patients with high TS expression. This difference in survival among patients with low- and high-TS-expressing tumors became more significant when the analysis was restricted to the 73 patients receiving 5-FU-based adjuvant therapy (RR = 0.37; 95% CI = 0.16-0.86; P = 0.0006). In contrast, 5-FU-based adjuvant therapy did not influence survival among patients with low-TS-expressing pancreatic cancer. CONCLUSIONS: High TS expression is a marker of poor prognosis in resected pancreatic cancer. Patients with high intratumoral TS expression benefit from adjuvant therapy.     

Thymidylate synthase expression in colorectal cancer: a prognostic and predictive marker of benefit from adjuvant fluorouracil-based chemotherapy.

PURPOSE: We studied the prognostic value of thymidylate synthase (TS) expression in primary colorectal cancer (CRC) and the role of TS expression as a predictor of chemotherapeutic benefit in patients treated with adjuvant chemotherapy. PATIENTS AND METHODS: TS expression was immunohistochemically assessed on tumor sections from 862 patients with CRC Dukes' stages B and C enrolled onto randomized trials evaluating fluorouracil (5-FU)-based adjuvant chemotherapy. RESULTS: TS expression was an independent prognostic factor for disease-free (P =.05) and overall survival (P =.05). In the subgroup treated with surgery alone, TS was an independent prognostic factor for disease-free (P <.001) and overall survival (P =.001), whereas this was not the case in the subgroup of adjuvantly treated patients. Patients whose tumors expressed high TS levels had a tendency to improved outcome after adjuvant therapy (not significant). The group whose tumors expressed the highest TS grade, grade 3 (34% of the patients), had a significantly longer disease-free survival if they were treated with adjuvant therapy compared with surgery alone (multivariate analyses, P =.02), whereas patients whose tumors expressed low TS levels (28% of the patients) had an impaired outcome after adjuvant therapy (multivariate analyses: disease-free survival, P =.01; overall survival, P =.01). CONCLUSION: TS expression predicts for survival independent of Dukes' stage in patients with CRC treated with surgery alone. The study indicates that patients with high TS levels may benefit from adjuvant 5-FU-based chemotherapy. However, patients with low TS levels seem to have a worse outcome when treated with adjuvant chemotherapy.     

DCR3 locus is a predictive marker for 5-fluorouracil-based adjuvant chemotherapy in colorectal cancer

Adjuvant chemotherapy reduces the incidence of distant metastasis and increases survival of patients with colorectal cancer. However, predictive markers are needed to define subsets of patients with stage II and III disease that may benefit from adjuvant treatment. A secreted member of the TNF receptor superfamily, the decoy receptor 3 (DcR3), was reported to be amplified in colorectal cancer as a negative regulator of Fas-mediated apoptosis. We analyzed DcR3 gene copy number and protein expression in a large series of tumors from a randomized multicenter trial of 5-fluorouracil/mitomycin C (FU/MMC) adjuvant chemotherapy of the Swiss Group for Clinical Cancer Research (SAKK 40/81), using real-time quantitative PCR and immunohistochemistry on tumor microarrays. Results of gene status and protein expression of DcR3 were correlated with disease-free and overall survival of patients. We observed amplification of the DcR3 gene in 185/294 (63%) and overexpression of the DcR3 protein in 163/223 (73%) of colorectal tumors. Multivariate analysis showed no prognostic effect of DcR3 gene amplification and protein overexpression. However, adjuvant chemotherapy was significantly more beneficial in patients with normal DcR3 gene copy number than in patients with amplification (DFS: HR 2.84, 95% CI 1.16-6.98, p = 0.02; OS: HR 3.15, 95% CI 1.19-8.32, p = 0.02), whereas DcR3 protein overexpression did not influence the effect of adjuvant chemotherapy (DFS: HR 1.02, 95% CI 0.65-1.60, p = 0.95; OS: HR 0.95, 95% CI 0.61-1.49, p = 0.83). We conclude that amplification of the 20q13 locus is a predictive marker for adjuvant chemotherapy in colorectal cancer.     

Dihydropyrimidine dehydrogenase and thymidylate synthase in colon carcinoma

Dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) in cancer are considered to play key roles in the sensitivity to 5-FU-based chemotherapy. We measured DPD activities and TS content in cancer and normal mucosa obtained from 59 patients with colorectal carcinomas and examined their relationship and clinicipathological relevance. DPD activity was significantly decreased in cancer compared to that in adjacent mucosa, irrespective of the clinicopathological parameters (p < 0.0001), while TS content was significantly increased in cancer (p < 0.0001). DPD activity in cancer correlated with that of the normal mucosa (r = 0.57, p < 0.001), but no correlation was found between TS content of normal mucosa and cancer. The DPD activity difference between cancer and normal mucosa was significantly correlated with difference in TS content (r = 0.70, p < 0.0001). These results suggest that the reduction of DPD activity is associated with the elevation of TS content, which may be connected with the development of 5-FU resistance and the effectiveness of biochemical modulation through the stabilization of TS inhibition with folic acid in colon carcinoma.