Thymidilate synthase expression predicts longer survival in patients with stage II colon cancer treated with 5-flurouracil independently of microsatellite instability

Rate of dissemination and prognosis in early and advanced stage colorectal cancer based on microsatellite instability status: systematic review and meta-analysis

INTRODUCTION

For the past two decades, microsatellite instability (MSI) has been reported as a robust clinical biomarker associated with survival advantage attributed to its immunogenicity. However, MSI is also associated with high-risk adverse pathological features (poorly differentiated, mucinous, signet cell, higher grade) and exhibits a double-edged sword phenomenon. We performed a systematic review and meta-analysis to evaluate the rate of dissemination and the prognosis of early and advanced stage colorectal cancer based on MSI status.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, Clinical Trials databases from inception of database to June 2019. Colorectal cancer, microsatellite instability, genomic instability and DNA mismatch repair were used as key words or MeSH terms. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were pooled using a random-effects model with odds ratio (OR) as the effect size. Statistical analysis was performed using RevMan ver 5.3 Cochrane Collaboration.

RESULTS

From 5288 studies, 136 met the inclusion criteria (n = 92,035; MSI-H 11,746 (13%)). Overall, MSI-H was associated with improved OS (OR, 0.81; 95% CI 0.73-0.90), DFS (OR, 0.73; 95% CI 0.66-0.81) and DSS (OR, 0.69; 95% CI 0.52-0.90). Importantly, MSI-H had a protective effect against dissemination with a significantly lower rate of lymph node and distant metastases. By stage, the protective effect of MSI-H in terms of OS and DFS was observed clearly in stage II and stage III. Survival in stage I CRC was excellent irrespective of MSI status. In stage IV CRC, without immunotherapy, MSI-H was not associated with any survival benefit.

CONCLUSIONS

MSI-H CRC was associated with an overall survival benefit with a lower rate of dissemination. Survival benefit was clearly evident in both stage II and III CRC, but MSI-H was neither a robust prognostic marker in stage I nor stage IV CRC without immunotherapy.

Determination of thymidine phosphorylase expression level facilitates recurrence risk stratification in stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines

The present study aimed to prospectively clarify the prognostic effect of the expression of several genes that are known to modulate 5-fluorouracil effects in 63 patients who underwent curative resection for stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines between 2008 and 2012. Thymidine phosphorylase (TP) expression in primary tumours was significantly lower in the recurrence group compared with the no-recurrence group (P=0.03), whereas, expression levels of genes that encoded thymidylate synthase, dihydropyrimidine dehydrogenase, folylpolyglutamate synthase, γ-glutamyl hydrolase and dihydrofolate reductase were not statistically different in tumours from the recurrence and no-recurrence groups. In the multivariate analysis using stepwise Cox proportional hazards regression, the following factors were significantly associated with shorter relapse-free survival following adjuvant chemotherapy with oral fluoropyrimidines: Venous invasion [present; hazard ratio (HR)=6.51; 95% confidence interval (CI): 1.55-27.4; P=0.01), Tumour-Node-Metastasis stage (3b; HR=6.18; 95% CI: 1.36-28.2; P=0.02) and TP expression (low; HR=9.61; 95% CI: 1.81-51.0; P=0.04). Patients with two or more risk characteristics had significantly shorter 5-year relapse-free survival compared with patients with one or no risk characteristics (55.8 vs. 91.8%; log-rank P=0.0006). We concluded that low TP expression is an independent predictive factor for poor prognosis in colorectal cancer. Therefore, determining TP expression may help to improve recurrence risk stratification in patients with stage II/III colorectal cancer following adjuvant chemotherapy with oral fluoropyrimidines.

Loss of LKB1 Protein Expression Correlates with Increased Risk of Recurrence and Death in Patients with Resected, Stage II or III Colon Cancer

PURPOSE

The purpose of this study was to investigate the prognostic significance of liver kinase b1 (LKB1) loss in patients with operable colon cancer (CC).

Materials and Methods

Two hundred sixty-two specimens from consecutive patients with stage III or high-risk stage II CC, who underwent surgical resection with curative intent and received adjuvant chemotherapy with fluoropyrimidine and oxaliplatin, were analyzed for LKB1 protein expression loss, by immunohistochemistry as well as for KRAS exon 2 and BRAFV600E mutations by Sanger sequencing and TS, ERCC1, MYC, and NEDD9 mRNA expression by real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

LKB1 expression loss was observed in 117 patients (44.7%) patients and correlated with right-sided located primaries (p=0.032), and pericolic lymph nodes involvement (p=0.003), BRAFV600E mutations (p=0.024), and TS mRNA expression (p=0.041). Patients with LKB1 expression loss experienced significantly lower disease-free survival (DFS) (hazard ratio [HR], 1.287; 95% confidence interval [CI], 1.093 to 1.654; p=0.021) and overall survival (OS) (HR, 1.541; 95% CI, 1.197 to 1.932; p=0.002), compared to patients with LKB1 expressing expressing tumors. Multivariate analysis revealed LKB1 expression loss as independent prognostic factor for both decreased DFS (HR, 1.217; 95% CI, 1.074 to 1.812; p=0.034) and decreased OS (HR, 1.467; 95% CI, 1.226 to 2.122; p=0.019).

CONCLUSION

Loss of tumoral LKB1 protein expression, constitutes an adverse prognostic factor in patients with operable CC.

The Prognostic and Predictive Value of Dihydropyrimidine Dehydrogenase-Related Indicators in Clinical Outcomes of Chemotherapy in Colorectal Cancer Patients: a Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the third most common cancer worldwide. Predictive biomarkers are needed to predict patients' outcomes and to select a chemotherapy regimen. We assessed whether dihydropyrimidine dehydrogenase (DPD)-related indicators can predict CRC patients' outcomes. We searched the studies in PubMed, EmBase, and the Cochrane Library up to March 4, 2018. We mainly analyzed different CRC patients' outcomes according to specific DPD-related indicators. Twenty-five articles were included in the meta-analysis. The results showed that for disease-free survival (DFS), low DPD expression was significantly superior to high expression (I² = 72%; HR: 1.59; 95%CI: 1.21-2.09; p = 0.001). However, this result had a potential publication bias (Begg's test: p = 0.007; Egger's test: p = 0.004). Among patients treated with chemotherapy, a high thymidylate phosphorylase (TP)/DPD ratio was advantageous for DFS (I² = 63.7%; HR: 0.65; 95%CI: 0.46-0.92; p = 0.015), and this result did not have a publication bias. For overall survival (OS), low DPD expression was superior to high expression (I² = 74.4%; HR: 2.11; 95%CI: 1.48-3.00; p < 0.001), although this result had a publication bias (Egger's test: p = 0.003; Begg's test: p = 0.010). There was no difference in OS according to the TP/DPD ratio (I² = 0%; HR: 0.92; 95%CI: 0.75-1.13; p = 0.420). DFS and OS were better in CRC patients with low DPD expression than in those with high DPD expression. However, because of publication bias, more DPD indicator-related studies, especially with negative results, are still needed. Patients with a high TP/DPD ratio have better DFS but not OS.

COLON AND RECTAL CANCER ARE DIFFERENT TUMOR ENTITIES ACCORDING TO EPIDEMIOLOGY, CARCINOGENESIS, MOLECULAR- AND TUMOR BIOLOGY, PRIMARY AND SECONDARY PREVENTION: PRECLINICAL EVIDENCE

Introduction.Colon and rectal cancer (CC, RC) are different entities from a clinical and tumor biological point of view. Up to now, both, CC and RC, are synonymously called  “Colorectal Cancer” (CRC). With our experience in basic and clinical research and routine  work in this field we now have come to the opinion, that the term “CRC” should definitely be questioned, and if justified, be abandoned.

Materials/Methods.We analyzed the actual available data from the literature and our own  results from the Ulm based study group FOGT to proof or reject our hypothesis.

Results.The following evident differences were recognized: Anatomically, the risk to  develop RC is 4× higher than for CC. Molecular changes in carcinogenesis in CC are different from RC. Physical activity helps to prevent CC, not RC. Pathologically there are differences between RC and CC. In addition, there are also major clinical differences  between CC and RC, such as in surgical topography and– procedures, multimodal treatment  (MMT) approaches (RC in MMT is less sensitive to chemotherapy than CC), and prognostic  factors for the spontaneous course and for success of MMT (e.g. TS or DPD ). Discussion. CC ´sand RC´s definitely are different in parameters of causal and formal carcinogenesis, effectivity of primary prevention by physical activity, conventional and  molecular pathology.According to our findings we can demand from the preclinical point of  view that CC and RC are two different tumor entities in terms of various representative  biological characteristics.CC and RC are also differing substantially in many clinical features, as outlined in a separate paper from our group.

Conclusion.“CRC” should no longer be used in basic and clinical research and other fields  of cancer classification as a single disease entity. CC is not the same as RC. CC might even be divided into right and left CC.

Are Colon and Rectal Cancer Two Different Tumor Entities? A Proposal to Abandon the Term Colorectal Cancer

Colon cancer (CC) and rectal cancer (RC) are synonymously called colorectal cancer (CRC). Based on our experience in basic and clinical research as well as routine work in the field, the term CRC should be abandoned. We analyzed the available data from the literature and results from our multicenter Research Group Oncology of Gastrointestinal Tumors termed FOGT to confirm or reject this hypothesis. Anatomically, the risk of developing RC is four times higher than CC, while physical activity helps to prevent CC but not RC. Obvious differences exist in molecular carcinogenesis, pathology, surgical topography and procedures, and multimodal treatment. Therefore, we conclude that CC is not the same as RC. The term "CRC" should no longer be used as a single entity in basic and clinical research as well as other areas of classification.

Thymidine phosphorylase expression and prognosis in colorectal cancer treated with 5-fluorouracil-based chemotherapy: A meta-analysis

In the past decades, various studies have suggested a possible link between thymidine phosphorylase (TP) level and colorectal cancer (CRC) treated with 5-fluorouracil (5-FU)-based chemotherapy; however, they have arrived at inconsistent results. Therefore, the present meta-analysis aimed to disclose a more comprehensive evaluation of this relationship. PubMed, the Cochrane Library, Ovid MEDLINE, Embase and China National Knowledge Infrastructure were systematically searched for studies that evaluated the prognostic value of TP in CRC. Stata 12.0 software was used to test the heterogeneity and evaluate the overall test performance. A total of 15 studies, including 1,225 patients, were included. The summary estimates of TP for CRC treated with 5-FU-based chemotherapy indicated a moderately positive prognosis with a hazard ratio (HR) of 0.76 (P=0.031) for overall survival and a HR of 0.711 (P=0.022) for relapse-free survival. On the basis of the present meta-analysis, TP could be promising and meaningful in the prognosis of CRC treated with 5-FU-based chemotherapy.

Implications of Circadian Rhythm Regulation by microRNAs in Colorectal Cancer

Aim

To establish a connection between microRNA (miRNAs), circadian rhythm, and colorectal cancer patient survival.

Methods

Genomic and clinical data were extracted from The Cancer Genome Atlas (TCGA) colorectal cancer database, and the expression levels of candidate miRNAs and a set of circadian rhythm-related genes (Per1, Per2, Per3, Bmal1), and genes associated with chemosensitivity (thymidylate synthase, dihydrofolate reductase) were assessed for any correlations among their expression. In addition, survival analyses specific to different colorectal cancer stages were performed to determine if these genes contribute to patient outcomes.

Results

Significant inverse correlation between the expression of Per1 and that of miR-192 and miR-194 was observed. In survival analyses, high miR-192 and miR-194 correlate with better overall survival in Stage II patients, but worse survival in more advanced Stage III/IV patients. The expression of Per1, but Per2 or Bmal1, is marginally associated with patient survival for Stage II patients. Low thymidylate synthase expression correlates with better overall survival in Stage II patients but worse survival in Stage III/IV patients.

Conclusion

This study establishes a foundation based on a large genomic database of colorectal cancer, for further investigation into the importance of regulatory mechanisms of circadian rhythm by miRNAs in colorectal cancer.

A synonymous EGFR polymorphism predicting responsiveness to anti-EGFR therapy in metastatic colorectal cancer patients

Genetic factors are known to affect the efficiency of therapy with monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR) in patients with metastatic colorectal cancer (mCRC). At present, the only accepted molecular marker predictive of the response to anti-EGFR mAbs is the somatic mutation of KRAS and NRAS as a marker of resistance to anti-EGFR. However, only a fraction of KRAS wild-type patients benefit from that treatment. In this study, we show that the EGFR gene polymorphism rs1050171 defines, independently of RAS mutational status, a sub-population of 11 % of patients with a better clinical outcome after anti-EGFR treatment. Median PFS for patients with the GG genotype was 10.17 months compared to 5.37 of those with AG + AA genotypes. Taken together, our findings could be used to better define CRC populations responding to anti-EGFR therapy. Further studies in larger independent cohorts are necessary to validate the present observation that a synonymous polymorphism in EGFR gene impacts on clinical responsiveness.

Evaluation of 5-fluorouracil metabolic enzymes as predictors of response to adjuvant chemotherapy outcomes in patients with stage II/III colorectal cancer: a decision-curve analysis

BACKGROUND

The effectiveness of 5-fluorouracil (5-FU)-based adjuvant chemotherapy is reported in patients with colorectal cancer (CRC), but the usefulness of 5-FU metabolic enzymes as predictive biomarkers of the efficacy of this chemotherapy remains unclear.

OBJECTIVE

This study aims to verify whether 5-FU metabolic enzymes are predictive biomarkers in the clinical setting of adjuvant chemotherapy for stage II/III CRC.

METHODS

In total, 179 patients with stage II/III CRC who were treated at our institute between 2000 and 2010 were enrolled. Messenger RNA (mRNA) expression of major 5-FU metabolic enzymes, namely thymidylate synthase, dihydropyrimidine dehydrogenase, thymidine phosphorylase (TP), orotate phosphoribosyl transferase, and β-actin (control) was evaluated using the Danenberg Tumor Profile method. mRNA expression and other clinicopathological data were investigated with regard to CRC relapse.

RESULTS

A total of 78 patients underwent surgery alone, while 101 underwent adjuvant chemotherapy (5-FU plus leucovorin [LV] or tegafur plus uracil /LV) following surgery. Relapse-free survival was longer and risk of recurrence was lower in association with high TP mRNA expression than in association with low TP mRNA expression in the adjuvant chemotherapy group (hazard ratio 0.66; 95 % confidence interval 0.47-0.92; p = 0.016), but not in the surgery alone group. mRNA expression of no other enzymes was associated with relapse in both groups. In decision-curve analyses, the predictive efficiency of TP mRNA expression plus clinicopathological factors was slightly better than that of clinicopathological factors only.

CONCLUSIONS

TP mRNA expression in tumors predicted the effects of adjuvant chemotherapy for stage II/III CRC, although the beneficial effects were marginal.

Expression analysis of genes involved in DNA repair or synthesis in mixed neuroendocrine/nonneuroendocrine carcinomas

BACKGROUND

Mixed neuroendocrine/nonneuroendocrine carcinomas are heterogeneous tumors with poorly defined diagnostic and clinical features and without pathological or molecular markers of prognosis or markers predicting their response to therapy. We aimed at analyzing the pathological features and the expression of genes involved in DNA repair or synthesis in a cohort of patients with mixed carcinomas from different sites as compared to the patients' outcome.

METHODS

Relative cDNA quantification of ribonucleotide reductase, large subunit 1, excision repair cross-complementation group 1, thymidylate synthase and topoisomerase IIa genes was tested using real-time PCR on microdissected neuroendocrine and nonneuroendocrine tumor components of 42 mixed cases (from the lung as well as the gastrointestinal and genitourinary tracts) and on 45 control cases of pure neuroendocrine and nonneuroendocrine carcinomas.

RESULTS

The expression levels of all genes were stable comparing nonneuroendocrine and neuroendocrine components of mixed cases (except for topoisomerase IIa in lung samples) but significantly different as compared to control nonneuroendocrine and neuroendocrine tumors. In the multivariate analysis including all clinical and pathological parameters and gene expression levels available, a predominant nonneuroendocrine component, the administration of additional therapy other than surgery and a high thymidylate synthase expression in nonneuroendocrine tumor tissue were significantly associated with a lower risk of a patient's death.

CONCLUSIONS

Our data show that mixed neuroendocrine/nonneuroendocrine carcinomas are different at the molecular level from their pure neuroendocrine and nonneuroendocrine counterparts, and detailed analyses of their clinical, pathological and molecular features may improve the clinical strategies for the treatment of these rare and underestimated tumors.

Correlation between expression of thymidylate synthase and clinical outcome of advanced gastric cancer treated with capecitabine alone chemotherapy

Thymidylate synthase (TS) is a prognostic marker in various tumors. However, the results of previous investigations in gastric cancer (GC) were controversial. The objective of this article is to investigate whether TS expression is associated with clinical outcome in advanced GC receiving capecitabine alone chemotherapy. The study reviewed 58 cases of advanced GC in patients aged ≥65 years between December 2008 and June 2012. All patients were treated with capecitabine alone chemotherapy. Immunohistochemical staining for TS protein expression was performed. The relationships between TS expression and clinicopathological characteristics (included age, gender, number of metastatic sites, Eastern Cooperative Oncology Group (ECOG) score, differentiation, and lymph node metastatic status), chemotherapy response, progression-free survival (PFS), and overall survival (OS) were evaluated. There was no association between TS expression and age, gender, number of metastatic sites, ECOG score, differentiation, and lymph node metastatic status (P > 0.05). The chemotherapy response rates among patients with low- and high-level expression of TS protein were 52.0 % (13/25) and 21.2 % (7/33), respectively (χ (2) = 5.968, P = 0.015). The median PFS and OS in patients with low-level TS expression were significantly longer than those with high-level TS expression (PFS 8.0 vs 2.8 m, P = 0.001; OS 13.3 vs 7.9 m, P = 0.002, respectively). Multivariate Cox regression analysis revealed that TS expression was independent risk factor for OS (hazard ratio (HR) 0.237; 95 % confidence interval (CI) 0.108 to 0.520; P = 0.000). The present study demonstrates that TS expression is associated with chemotherapy response, PFS, and OS in advanced GC patients treated with capecitabine alone chemotherapy.

Role of topoisomerase I and thymidylate synthase expression in sporadic colorectal cancer: associations with clinicopathological and molecular features

Topoisomerase I (Topo I) and thymidylate synthase (TS) are essential enzymes for the replication, transcription and repair of DNA, and are potential biomarkers in colorectal cancer (CRC). The aim of the study was to correlate the tissue expression of Topo I and TS in sporadic CRCs with relevant pathological and molecular features and patients' outcome. Topo I and TS expression was assessed by immunostaining in 112 consecutive primary CRCs. Increased expression of Topo I was found in 36% of tumors, preferentially rectal (50%) and with not otherwise specified (NOS) histology (44%). Topo I expression was associated with 18q allelic loss (LOH), (p=0.013), microsatellite stable phenotype (p=0.002) and normal expression of mismatch proteins hMLH1 and hMSH2 (p=0.0012 and p=0.02, respectively). High TS expression was found in 60% of tumors, more frequently in distal sites (62%) and with NOS histology (66%); no association with microsatellite instability was observed. Topo I seems to be involved in the chromosomal instability pathway of sporadic CRCs. Conversely, high TS expression is unlikely to affect the clinical behavior of microsatellite unstable CRCs.

Management of stage II colon cancer - the use of molecular biomarkers for adjuvant therapy decision

BACKGROUND

There is uncertainty on the benefit of adjuvant chemotherapy in patients with stage II colorectal cancers. The aim of this study is to investigate the combined role of clinical, pathological and molecular parameters to identify those stage II patients who better benefit from adjuvant therapy.

METHODS

We examined 120 stage II colon cancer patients. Of these, 60 patients received adjuvant 5-FU chemotherapy after surgery and the other 60 did not receive therapy. Immunohistochemical (IHC) analyses were performed to evaluate the expressions of Thymidylate synthetase (TYMS), TP53 (p53), β-catenin (CTNNB1) and CD8. For TYMS, its mRNA expression levels were also investigated by real time qRT-PCR. The entire case study was characterized by the presence of a defect in the MMR (mismatch repair) system, the presence of the CpG island methylator phenotype (CIMP or CIMP-High) and for the V600E mutation in the BRAF gene. At the histo-pathological level, the depth of tumour invasion, lymphovascular invasion, invasion of large veins, host lymphocytic response and tumour border configuration were recorded.

RESULTS

The presence of the V600E mutation in the BRAF gene was a poor prognostic factor for disease free and overall survival (DFS; hazard ratio [HR], 2.57; 95% CI: 1.03 -6.37; p = 0.04 and OS; HR, 3.68; 95% CI: 1.43-9.47; p < 0.01 respectively), independently of 5-FU treatment. Adjuvant therapy significantly improved survival in patients with high TYMS levels (p = 0.04), while patients with low TYMS had a better outcome if treated by surgery alone (DFS; HR, 6.07; 95% CI, 0.82 to 44.89; p = 0.04). In patients with a defect in the MMR system (dMMR), 5-FU therapy was associated to reduced survival (DFS; HR, 37.98; 95% CI, 1.04 to 1381.31; p = 0.04), while it was beneficial for CIMP-High associated tumours (DFS; HR, 0.17; 95% CI, 0.02 to 1.13; p = 0.05).

CONCLUSIONS

Patients' characterization according to MMR status, CIMP phenotype and TYMS mRNA expression may provide a more tailored approach for adjuvant therapy in stage II colon cancer.

Role of conventional chemosensitivity test and tissue biomarker expression in predicting response to treatment of peritoneal carcinomatosis from colon cancer

Peritoneal carcinomatosis (PC) is observed in approximately 10% of patients with colorectal cancer at the time of primary cancer resection. Most of these patients receive 5-fluorouracil (5-FU)- or oxaliplatin-containing chemotherapy regimens as first-, second-, or third-line treatment. In the present study, sensitivity and resistance to drugs used to treat PC were better defined by a conventional chemosensitivity test than by biomarker expression.

BACKGROUND

5-Fluorouracil- or oxaliplatin-based regimens are the treatments of choice in patients with PC from colon cancer. There are currently no useful preclinical evaluations to guide the decision-making process for tailored therapy. The aim of the present study was to compare the advantages and limits of a conventional in vitro chemosensitivity test with those of a panel of biomolecular markers in predicting clinical response to different drugs used to treat colon cancer-derived PC.

PATIENTS AND METHODS

Fresh surgical biopsy specimens were obtained from 28 patients with peritoneal carcinomatosis from colon cancer. TS, TP, DPD, MDR1, MRP-1, MGMT, BRCA1, ERCC1, GSTP1, and XPD gene expression levels were determined by real-time reverse transcription polymerase chain reaction. An in vitro chemosensitivity test was used to define a sensitivity or resistance profile to the drugs used to treat each patient.

RESULTS

Expression levels of the genes analyzed were generally poorly related to each other. TS and ERCC1 expression was inversely related to response to 5-FU-and/or oxaliplatin-containing regimens. Significant predictivity in terms of sensitivity but poor predictivity of resistance (56.2%) (P=.037) were observed for ERCC1 expression (90%), and high predictivity of resistance (100%) but very low predictivity of sensitivity (40%) (P=.014) were registered for TS. The best overall and significant predictivity was observed for chemosensitivity test results (62.5% sensitivity and 89% resistance; P=.005).

CONCLUSIONS

Sensitivity and resistance to drugs used in vivo was better defined by the chemosensitivity test than by biomarker expression.

Expression of pim-1 in tumors, tumor stroma and tumor-adjacent mucosa co-determines the prognosis of colon cancer patients

Provirus integration site for Moloney murine leukemia virus (pim-1) is a proto-oncogene that is linked to the development and progression of several cancers. In this study, we evaluated pim-1 expression in tumors, tumor stroma and tumor-adjacent mucosa together as an independent prognostic factor for colon cancer patients. The study included 343 colon cancer patients. Immunohistochemical staining was used to detect pim-1. Multivariate cox regression for disease-free survival (DFS) were used to identify independent prognostic factors. Analytic hierarchy process (AHP) was used to calculate the weight of pim-1 in tumors, tumor stroma and tumor-adjacent mucosa in order to obtain a Pim-1 total score (PTS) for recurrence and survival. Kaplan-Meier DFS curves and OS curves for patients with different pim-1 expression levels were compared using the log-rank test. In this study, four independent prognostic factors were identified for colon cancer patients: pim-1 expression in tumors, tumor stroma, tumor-adjacent mucosa, as well as tumor stage. It has been established that clinical stage is an important prognostic factor for colon cancer patients. However, PTS can identify the patients who are likely to recur not only in the whole radical excision group but also within each stage of this group. Based on the results of this study we can conclude that the PTS combined with clinical staging system may be a better predictor of colon cancer patients' prognosis than using the clinical stage system alone. ClinicalTrials.gov Number: ChiCTR-PRCH-12002842.

A combined analysis of mismatch repair status and thymidylate synthase expression in stage II and III colon cancer

This study in 716 colon cancer patients evaluates if a combined instead of a single marker analysis of mismatch repair (MMR) status and thymidylate synthase (TS) expression could individualize the treatment decision. The results indicate that a combined analysis of MMR status and TS expression can improve prediction of response to adjuvant 5-fluorouracil (5-FU)-based chemotherapy in stage III colon cancer.

BACKGROUND

Colon 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 METHODS

This 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.

RESULTS

There 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.

CONCLUSIONS

A 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 and prognosis in colorectal cancer: a meta-analysis of colorectal cancer survival data

BACKGROUND

Although many studies have investigated the prognostic effect of thymidylate synthase (TS) in colorectal cancer, no consensus has been reached. The aim of this meta-analysis was to obtain a more precise estimate of the prognostic significance of TS expression in localized cancers treated by curative resection and adjuvant chemotherapy.

MATERIALS AND METHOD

Seventeen eligible studies reporting survival in 2,893 patients stratified by TS expression were pooled using a fixed- or random-effects model. The main outcome measure was hazard ratio (HR).

RESULTS

The overall HR for overall survival was 1.01 (95% CI 0.74-1.39, p=0.947), with an I2 of 64.4%. The total HR for disease-free survival was 1.36 (95% CI 0.97-1.89, p=0.072), with an I2 of 75.8%. In the TS protein-tested subgroup, the total HR for disease-free survival was 1.72 (95% CI 1.02-2.89, p=0.042), with an I2 of 81.3%.

CONCLUSION

Our meta-analysis showed that, in the adjuvant setting, TS expression does not predict a poorer disease-free survival or a worse overall survival. Therefore, we believe that it is inappropriate to regard TS expression as a prognostic factor for patients with stage II and stage III colorectal cancer treated by surgery and adjuvant chemotherapy.

Chemoprevention, chemotherapy, and chemoresistance in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death in industrialized countries. Chemoprevention is a promising approach, but studies demonstrating their usefulness in large populations are still needed. Among several compounds with chemopreventive ability, cyclooxygenase inhibitors have received particular attention. However, these agents are not without side effects, which must be weighed against their beneficial actions. Early diagnosis is critical in the management of CRC patients, because, in early stages, surgery is curative in >90% of cases. If diagnosis occurs at stages II and III, which is often the case, neoadjuvant chemotherapy and radiotherapy before surgery are, in a few cases, recommended. Because of the high risk of recurrence in advanced cancers, chemotherapy is maintained after tumor resection. Chemotherapy is also indicated when the patient has metastases and in advanced cancer located in the rectum. In the last decade, the use of anticancer drugs in monotherapy or in combined regimens has markedly increased the survival of patients with CRC at stages III and IV. Although the rate of success is higher than in other gastrointestinal tumors, adverse effects and development of chemoresistance are important limitations to pharmacological therapy. Genetic profiling regarding mechanisms of chemoresistance are needed to carry out individualized prediction of the lack of effectiveness of pharmacological regimens. This would minimize side effects and prevent the selection of aggressive, cross-resistant clones, as well as avoiding undesirable delays in the use of the most efficient therapeutic approaches to treat these patients.