Molecular and biochemical markers in colorectal cancer

Colon and rectal cancer: An emergent public health problem

Colorectal cancer ranks third globally, with a high mortality rate. In the United States, and different countries in Europe, organized population screenings exist and include people between 50 and 74 years of age. These screenings have allowed an early diagnosis and consequently an improvement in health indicators. Colon and rectal cancer (CRC) is a disease of particular interest due to the high global burden associated with it and the role attributed to prevention and early diagnosis in reducing morbidity and mortality. This study is a review of CRC pathology and includes the most recent scientific evidence regarding this pathology, as well as a diagnosis of the epidemiological situation of CRC. Finally, the recommendation from a public health perspective will be discussed in detail taking into account the context and the most current recommendations.

Carbohydrate antigen 125 supplements carbohydrate antigen 19-9 for the prediction of invasive intraductal papillary mucinous neoplasms of the pancreas

BACKGROUND

Intraductal papillary mucinous neoplasms (IPMNs) are characterized by their abundant mucin production and malignant potential. IPMNs of the pancreas are mainly managed according to their radiographic indications, but this approach lacks accuracy with regard to IPMN grading. Therefore, serological biomarkers such as CA19-9 and CA125 (MUC16) should be employed to assist in predicting the invasiveness of IPMNs.

METHODS

We investigated the preoperative serum levels of CA19-9, CA125 and CEA in 381 surgical patients with a definite pathological diagnosis of IPMN from July 2010 to December 2019 at the Shanghai Cancer Center. We calculated the Youden indices of each point on the receiver operating characteristic (ROC) curves to identify the most appropriate cut-off values of CA19-9, CA125 and CEA for recognizing malignant IPMNs. Serological biomarker differences were correlated with clinicopathological features of IPMNs, and diagnostic indices of different scenarios were calculated to find the optimum strategy.

RESULTS

The malignant group had higher serum levels of CA19-9, CA125 and CEA. According to the ROC curves, the cut-off values of CA19-9, CA125 and CEA were readjusted to 38.3 U/ml, 13.4 U/ml and 5.3 μg/L. CA19-9 elevation was significantly associated with vascular invasion and perineural infiltration. CA125 showed good efficacy in predicting invasive IPMN in the CA19-9-negative subgroup.

CONCLUSIONS

Serological biomarkers are useful and sensitive indicators for recognizing invasive IPMNs. CA19-9 is the most important diagnostic index among all routinely measured serum biomarkers for differentiating malignant from benign IPMNs. CA19-9 should be combined with CA125 to enable more accurate predictions of IPMN malignancy.

Predicting Microsatellite Instability Status in Colorectal Cancer Based on Triphasic Enhanced Computed Tomography Radiomics Signatures: A Multicenter Study

Background

This study aimed to develop and validate a computed tomography (CT)-based radiomics model to predict microsatellite instability (MSI) status in colorectal cancer patients and to identify the radiomics signature with the most robust and high performance from one of the three phases of triphasic enhanced CT.

Methods

In total, 502 colorectal cancer patients with preoperative contrast-enhanced CT images and available MSI status (441 in the training cohort and 61 in the external validation cohort) were enrolled from two centers in our retrospective study. Radiomics features of the entire primary tumor were extracted from arterial-, delayed-, and venous-phase CT images. The least absolute shrinkage and selection operator method was used to retain the features closely associated with MSI status. Radiomics, clinical, and combined Clinical Radiomics models were built to predict MSI status. Model performance was evaluated by receiver operating characteristic curve analysis.

Results

Thirty-two radiomics features showed significant correlation with MSI status. Delayed-phase models showed superior predictive performance compared to arterial- or venous-phase models. Additionally, age, location, and carcinoembryonic antigen were considered useful predictors of MSI status. The Clinical Radiomics nomogram that incorporated both clinical risk factors and radiomics parameters showed excellent performance, with an AUC, accuracy, and sensitivity of 0.898, 0.837, and 0.821 in the training cohort and 0.964, 0.918, and 1.000 in the validation cohort, respectively.

Conclusions

The proposed CT-based radiomics signature has excellent performance in predicting MSI status and could potentially guide individualized therapy.

Association of KRAS mutation with tumor deposit status and overall survival of colorectal cancer

PURPOSE

To examine associations of KRAS mutation with tumor deposit status and overall survival in colorectal cancer (CRC) patients.

METHODS

This retrospective cohort study included patients with incidental CRC diagnosed during 2010-2014 and recorded statuses of KRAS and tumor deposit in the National Cancer Database of the USA. Multivariable logistic regression and time-varying Cox regression analyses were used.

RESULTS

We included 45,761 CRC patients with KRAS status (24,027 [52.5%] men, 24,240 [53.0%] < 65 years old, 17,338 [37.9%] with KRAS mutation). Adjusted for microsatellite instability, age, pathologic stage and tumor grade, KRAS mutation (versus wild type) was associated with tumor deposit presence (odds ratio = 1.11, 95% CI 1.02-1.20). KRAS mutation was also linked to worse overall survival of CRC patients regardless of tumor deposit status (adjusted Hazard ratio [HR] = 1.20, 95% CI 1.07-1.33 for CRC with tumor deposits, and adjusted HR = 1.24, 95% CI 1.14-1.35 or CRC without) or tumor stage (adjusted HR = 1.32, 95% CI 1.14-1.54 for early-stage and adjusted HR = 1.18, 95% CI 1.10-1.27 for late-stage). Microsatellite instability was associated with better overall survival in CRC without tumor deposit (adjusted HR = 0.89, 95% CI 0.79-0.99), but not in CRC with tumor deposit (adjusted HR = 1.12, 95% CI 0.97-1.30).

CONCLUSION

KRAS mutation is independently associated with tumor deposit presence and a worse overall survival in CRC patients.

p53 expression status is associated with cancer-specific survival in stage III and high-risk stage II colorectal cancer patients treated with oxaliplatin-based adjuvant chemotherapy

BACKGROUND

We attempted to elucidate whether p53 expression or TP53 mutation status was associated with cancer-specific survival in adjuvant FOLFOX-treated patients with stage III or high-risk stage II colorectal cancer (CRC).

METHODS

We analysed CRCs (N = 621) for the presence of TP53 alterations and for p53 expression, using targeted resequencing and immunohistochemistry. CRCs were grouped into four subsets according to the p53 expression status, which included p53-no, mild, moderate and strong expression.

RESULTS

The distributions of CRCs were 19.85, 11.05, 17.7% and 51.5% in the p53-no, mild, moderate and strong expression groups, respectively. Cases in the p53-mild to moderate expression group were associated with a more frequent proximal location, undifferentiated histology, lower N category, extraglandular mucin production, microsatellite instability, CIMP-P1, CK7 expression and decreased CDX2 expression compared with those of cases of the p53-no expression and p53-strong expression groups. According to survival analysis, the p53-mild expression group showed a poor 5-year relapse-free survival (hazard ratio (HR): 2.71, 95% confidence interval (CI) = 1.60-4.60, P < 0.001) and poor 5-year cancer-specific survival (HR: 2.90, 95% CI = 1.28-6.57, P = 0.011).

CONCLUSIONS

p53-mild expression status was found to be an independent prognostic marker in adjuvant FOLFOX-treated patients with stage III and high-risk stage II CRC.

Anti-colorectal cancer effects of anti-p21Ras scFv delivered by the recombinant adenovirus KGHV500 and cytokine-induced killer cells

BACKGROUND

Colorectal cancer (CRC) is the most common type of gastrointestinal cancer. CRC gene therapy mediated by adenovirus holds great promise for the treatment of malignancies. However, intravenous delivery of adenovirus exhibits limited anti-tumor activity in vivo when used alone.

METHODS

In this study, the antitumor activity of the recombinant adenovirus KGHV500 was assessed with the MTT, TUNEL, Matrigel invasion and cell migration assays. To enhance the intravenous delivery of KGHV500 in vivo, cytokine-induced killer (CIK) cells were used as a second vector to carry KGHV500. We explored whether CIK cells could carry the recombinant adenovirus KGHV500 containing the anti-p21Ras single chain fragment variable antibody (scFv) gene into tumors and enhance antitumor potency.

RESULTS

Our results showed that KGHV500 exhibited significant antitumor activity in vitro. In the nude mouse SW480 tumor xenograft model, the combination of CIK cells with KGHV500 could induce higher antitumor activity against colorectal cancer in vivo than that induced by either CIK or KGHV500 alone. After seven days of treatment, adenovirus and scFv were detected in tumor tissue but were not detected in normal tissues by immunohistochemistry. Therefore, KGHV500 replicates in tumors and successfully expresses anti-p21Ras scFv in a colorectal cancer xenograft model.

CONCLUSIONS

Our study provides a novel strategy for the treatment of colorectal cancer by combining CIK cells with the recombinant adenovirus KGHV500 which carried anti-p21 Ras scFv.

Overexpression of wild-type p21Ras plays a prominent role in colorectal cancer

Colorectal cancer (CRC) is the most common gastrointestinal type of cancer. The overexpression of Ras proteins, particularly p21Ras, are involved in the development of CRC. However, the subtypes of the p21Ras proteins that are overexpressed and the mutation status remain unknown restricting the development of therapeutic antibodies targeting p21Ras proteins. The present study aimed to investigate the mutation status of ras genes associated with Ras proteins that are overexpressed in CRC and explore whether or not wild-type p21Ras could be a target for CRC therapy. p21Ras expression was examined immunohistochemically in normal colorectal epithelium, benign lesions and malignant colorectal tumor tissues by monoclonal antibody (Mab) KGH-R1 which is able to react with three types of p21Ras proteins: H-p21Ras, N-p21Ras and K-p21Ras. Then, the expression levels of p21Ras subtypes were determined in CRC by a specific Mab for each p21Ras subtype. Mutation status of ras genes in p21Ras-overexpressing CRC was detected by DNA sequencing. There was rare p21Ras expression in normal colorectal epithelium but a high level of p21Ras expression in CRC, with a significant increase from normal colorectal epithelium to inflammatory polyps, low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia and invasive colorectal adenocarcinoma, respectively. Overexpression of K-p21Ras was found in all CRC tissues tested, overexpression of N-p21Ras was found in 85.7% of the CRC tissues, while H-p21Ras expression was not found in any CRC tissue. DNA sequencing showed that there were no K-ras mutations in 60% of the K-p21Ras-overexpressing CRC, while 40% of the CRC tissues harbored K-ras mutations. N-ras mutations were not found in any N-p21Ras-overexpressing CRC. Our findings indicate that overexpression of wild-type p21Ras may play a prominent role in the development of CRC in addition to ras mutations and could be a promising target for CRC therapy.

Association Between Specific Mutations in KRAS Codon 12 and Colorectal Liver Metastasis

IMPORTANCE

Currently, one of the most commonly available biomarkers in the treatment of patients with colorectal liver metastases (CRLM) is the Kirsten rat sarcoma viral oncogene homolog (KRAS); however, the prognostic implications of specific mutations of the KRAS gene are still not well defined.

OBJECTIVE

To investigate the prognostic impact of specific KRAS mutations on patients undergoing liver resection for CRLM.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective single-center study was conducted from January 1, 2003, to December 31, 2013. Data about specific KRAS mutations for 331 patients who underwent hepatic resection for CRLM at Johns Hopkins Hospital between 2003 and 2013 were analyzed. Clinicopathological characteristics, perioperative details, and outcomes were stratified by specific KRAS mutation at codons 12 and 13.

INTERVENTION

Resection of CRLM.

MAIN OUTCOMES AND MEASURES

Overall survival (OS) and recurrence-free survival.

RESULTS

A mutated KRAS (mtKRAS) was identified in 91 patients (27.5%). At a median follow-up of 27.4 months, recurrence was observed in 48 patients (52.7%) with mtKRAS and 130 patients (54.2%) with wild-type KRAS (wtKRAS) (P = .82). Median and 5-year survival among patients with mtKRAS was 32.4 months and 32.7%, respectively, vs 58.5 months and 46.9%, respectively, for patients with wtKRAS (P = .02). Patients with KRAS codon 12 mutations had worse OS (hazard ratio [HR], 1.54; 95% CI, 1.05-2.27; P = .03) vs those with wtKRAS, whereas a KRAS codon 13 mutation was not associated with prognosis (HR, 1.47; 95% CI, 0.83-2.62; P = .19). Among the 6 most common mutations in codons 12 and 13, only G12V (HR, 1.78; 95% CI, 1.00-3.17; P = .05) and G12S (HR, 3.33; 95% CI, 1.22-9.10; P = .02) were associated with worse OS compared with patients with wtKRAS (both P < .05). Among patients who recurred, G12V (HR, 2.96; 95% CI, 1.32-6.61; P = .01), G12C (HR, 6.74; 95% CI, 2.05-22.2; P = .002), and G12S mutations (HR, 4.91; 95% CI, 1.52-15.8; P = .01) were associated with worse OS (both P < .05).

CONCLUSIONS AND RELEVANCE

G12V and G12S mutations of codon 12 were independent prognostic factors of worse OS. Among patients who recurred after resection of CRLM, G12V, G12C, and G12S mutations were associated with worse OS. Information on specific KRAS mutations may help individualize therapeutic and surveillance strategies for patients with resected CRLM.

TWIST1 and SNAI1 as markers of poor prognosis in human colorectal cancer are associated with the expression of ALDH1 and TGF-β1

Epithelial-mesenchymal transition (EMT) is an important factor in cancer invasiveness and metastatic progression. During EMT, cancer cells acquire stem cell properties. The role of EMT and stemness in colon cancer has not been fully understood. We aimed to demonstrate the clinical significance of EMT and the stem cell phenotype in colorectal cancer. Two hundred and thirty-one surgically resected colon cancer cases were included in the present study. mRNAs of E-cadherin, TWIST1 and SNAI1 were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) (n=109). Immunohistochemical staining was performed for six markers (ALDH1, TGF-β1, E-cadherin, β-catenin, TWSIT1 and SNAI1) (n=231). We assessed clinicopathological characteristics according to the expression of the stem cell phenotype and EMT markers. Based on the results of qRT-PCR, TWIST1 and SNAI1 significantly influenced node metastasis (P=0.04 and P=0.02, respectively). High TWIST1 and SNAI1 mRNA expression was associated with poor overall survival according to the univariate analysis (P<0.01 and P=0.01, respectively) and the multivariate analysis (P=0.04 and P=0.04, respectively). ALDH1 expression as detected by immunohistochemical staining was associated with high nodal stage, advanced clinical stage, lymphatic invasion and poor survival (P=0.01, P=0.04, P<0.05 and P<0.01, respectively) and with the expression of TGF-β1 and β-catenin. In conclusion, in human colorectal cancer, the EMT markers TWIST1 and SNAI1 are suggested as important markers of poor prognosis. Their expression is associated with the expression of putative stem cell marker ALDH1, and ALDH1 is associated with the expression of TGF-β1.

Prognostic value of circulating cytokines for stage III colon cancer

BACKGROUND

This study was to determine preoperative serum levels of epidermal growth factor (EGF), interleukin-6 (IL-6), and C-reactive protein (CRP) in stage III colon cancer and correlate them with disease status and prognosis. The circulating EGF in correlation with primary site epidermal growth factor receptor (EGFR) was also evaluated.

METHODS

Seventy-seven patients with curatively resected stage III colon cancer were selected for analysis. Enzyme-linked immunosorbent assay was used to determine EGF and IL-6 serum levels, and serum CRP levels were measured via immunoturbidimetry. EGFR expression was observed with immunohistochemical studies.

RESULTS

The median levels of EGFR, IL-6, and CRP were 189.4 pg/mL, 9.09 pg/mL, and 1.4 mg/mL, respectively. The factors related to recurrence with statistical significance included positive node status (P = 0.041), lymphovascular invasion (P = 0.001), and preoperative IL-6 level ≥9 pg/mL (P = 0.020). CRP and EGF levels were not significantly associated with disease-free survival rates (P = 0.438 and P = 0.309, respectively). Multivariate analysis using Cox's proportion model revealed that lymph node status was the single independent prognostic factor for predicting time until recurrence (odds ratio, 4.99; 95% confidence interval, 1.09-22.91; P = 0.038).

CONCLUSION

IL-6 expression in stage III colon cancer patients appears to be a prognostic marker of tumor behavior. No correlations between serum EGF concentrations and tumor EGFR positivity were found in this study.

Molecular pathways in colorectal cancer

Colorectal cancer (CRC) is the second most common newly diagnosed cancer and accounts for the second highest number of cancer related deaths in Australia, the third worldwide and of increasing importance in Asia. It arises through cumulative effects of inherited genetic predispositions and environmental factors. Genomic instability is an integral part in the transformation of normal colonic or rectal mucosa into carcinoma. Three molecular pathways have been identified: these are the chromosomal instability (CIN), the microsatellite instability (MSI), and the CpG Island Methylator Phenotype (CIMP) pathways. These pathways are not mutually exclusive, with some tumors exhibiting features of multiple pathways. Germline mutations are responsible for hereditary CRC syndromes (accounting for less than 5% of all CRC) while a stepwise accumulation of genetic and epigenetic alterations results in sporadic CRC. This review aims to discuss the genetic basis of hereditary CRC and the different pathways involved in the process of colorectal carcinogenesis.

Relationship between expression of ras p21 oncoprotein and mutation status of the K-ras gene in sporadic colorectal cancer patients in Tunisia

INTRODUCTION

The K-ras proto-oncogene encodes a protein (p21-ras) belonging to the family of GTP/GDP-binding proteins with GTPase activity. The activation of ras family genes plays an important role in colorectal tumorigenesis. Frequency of K-ras mutations and overexpression of the protein in colorectal cancer (CRC) vary between 14% and 50% and between 29% and 76%, respectively.

AIMS

We investigated the clinicopathologic characteristics of patients with CRC and their relationship with point mutations of K-ras oncogene codons 12/13 and ras p21 expression.

MATERIALS AND METHODS

K-ras codons 12 and 13 point mutations were examined by direct sequence analysis, whereas the ras p21 expression was evaluated using immunohistochemistry.

RESULTS

Statistical analysis of immunohistochemical results showed that the expression of ras p21 was correlated with the advanced age of patients (P=0.0001), whereas loss of signal was associated with mucinous histotype (P=0.0001). Mutations in the K-ras gene were detected in 12 of the patients with CRC. Mutations in K-ras gene were found in 12 of 52 tumors (23.07%), and 7 mutations were G→A transitions (58.33% of all mutations), 4 were G→T transversions (33.33%), and only 1 was G→C transversion (8.33%). A total of 83.33% of the mutation occurred at codon 12 and 16.67% at codon 13. Moreover, K-ras mutations were associated with the sex of patients (P=0.017).

CONCLUSIONS

Genetic K-ras alterations were rather low in the Tunisian population, but further study is necessary to unravel the molecular background of CRC.

Influence of KRAS mutation status in metachronous and synchronous metastatic colorectal adenocarcinoma

BACKGROUND

Mutations in the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) are present in approximately 30% to 40% of colorectal adenocarcinomas. Wild-type (WT) KRAS mutation status is predictive of tumor response with epidermal growth factor receptor-directed therapies, but the results from studies evaluating the prognostic value of KRAS status in localized disease have been contradictory. The prognostic value of KRAS in metastatic disease, specifically according to whether patients have synchronous or metachronous disease at presentation, is less understood.

METHODS

One-hundred ten consecutive patients with metastatic colorectal adenocarcinoma underwent testing for KRAS exon 2 mutations by polymerase chain reaction amplification and direct nucleotide sequencing. The clinical characteristics, treatments, and outcomes of these patients were then analyzed retrospectively, stratified according to whether patients presented with synchronous or metachronous metastasis and according to KRAS mutation status (WT or mutated).

RESULTS

For the entire cohort, the median overall survival from the date of diagnosis of metastatic disease was 34.3 months (95% confidence interval, 28.3-49.4 months) for patients with WT KRAS (n = 70). The median overall survival for patients with mutated KRAS (n = 40) was 40.3 months (95% confidence interval, 27.9-51.1 months; log-rank P = .91). Kaplan-Meier survival analysis indicated that 3-year overall survival and 5-year overall survival were not statistically different. Within the subgroups of patients with synchronous and metachronous metastatic disease, no significant differences were observed in median overall survival, 3-year overall survival, or 5-year overall survival between the WT KRAS and mutated KRAS groups.

CONCLUSIONS

In this study, KRAS mutation status did not influence overall survival in either synchronous or metachronous metastatic colorectal adenocarcinoma and, as such, had no prognostic role in this disease setting.

The prognostic significant of percentage drop in serum CEA post curative resection for colon cancer

OBJECTIVE/BACKGROUND

This study aimed to analyze the hypothesis that increased percentage drop in serum CEA post curative resection for colon cancer is associated with improved survival.

METHODS

Five hundred thirty three patients who underwent colon resection with a curative intent were retrospectively analyzed for their pre- and postoperative CEA levels. The disease-free and overall survival curves were calculated using Kaplan Meier analysis to evaluate cancer related outcomes. For multivariate analysis, the Cox regression model was used.

RESULTS

The estimated 5-year overall survival for the preoperative serum CEA > 5 ng/mL group with respect to a postoperative CEA level drop rate of 40%, 50% and 60% were 72.9%, 80.9% and 81.8%, respectively. The estimated 5-year overall survival for the preoperative serum CEA ≤ 5 ng/mL group with respect to each postoperative CEA level drop rate were 86.6%, 97.1% and 97.7%, respectively (P = 0.257, P = 0.092 and P = 0.073, respectively). The prognostic factors for poor survival were the depth of invasion (p = 0.042, hazard ratio: 2.617, 95% CI = 1.021-3.012) and lymph node metastasis (p = 0.008, hazard ratio: 2.249, 95% CI = 1.231-4.111). A 60% drop of the CEA level was an independent prognostic factor for survival (p = 0.001, hazard ratio: 2.954, 95% CI = 1.686-5.176) for patients with a preoperative CEA level > 5 ng/mL.

CONCLUSION

Determining the preoperative CEA level and the early postoperative percent drop of the serum CEA level may be a helpful factor for the prognosis of colon cancer patients. However, the percent drop from the pre to postoperative CEA level from the normal range was not associated with survival difference.

Prognostic value of postoperative CEA clearance in rectal cancer patients with high preoperative CEA levels

PURPOSE

We determined the prognostic value of carcinoembryonic antigen (CEA) clearance after tumor resection with serial evaluation of postoperative CEA levels in rectal cancer.

METHODS

Between 1994 and 2004, we retrospectively reviewed 122 patients with rectal cancer whose serum CEA levels were measured on the preoperative day and postoperative days 7 and 30. Patients with preoperative CEA levels <5.0 ng/ml were excluded. An exponential trend line was drawn using the three CEA values. Patients were categorized into three groups based on R(2) values calculated through trend line, which indicates the correlation coefficient between exponential graph and measured CEA values: exponential decrease group (group 1: 0.9 < R(2) < or = 1.0), nearly exponential decrease group (group 2: 0.5 < R(2) < or = 0.9), and randomized clearance group (group 3: 0.5 < or = R(2)). We then analyzed the CEA clearance pattern as a prognostic indicator.

RESULTS

With a median follow-up of 57 months, the 5-year overall survival was 62.3% vs. 48.1% vs. 25% and the 5-year disease-free survival was 58.6% vs. 52.7% vs. 25% among groups 1, 2, and 3 (P = 0.014, P = 0.027, respectively) in patients with stage III rectal cancer. For those with stage II rectal cancer, the 5-year overall survival rate of group 1 was significantly better than groups 2 and 3 (88.8% vs. 74.1%, respectively, P = 0.021).

CONCLUSIONS

The postoperative pattern of CEA clearance is a useful prognostic determinant in patients with rectal cancer. Patients with a randomized pattern of CEA clearance after tumor resection should be regarded as having the possibility of a persistent CEA source and may require consideration of intensive follow-up or adjuvant therapy.

P53 mutations in colorectal cancer from northern Iran: Relationships with site of tumor origin, microsatellite instability and K-ras mutations

CRC-associated P53 mutations have not been studied extensively in non-Western countries at relatively low CRC risk. We examined, for the first time, 196 paraffin-embedded CRC cases from Northern Iran for mutations in P53 exons 5-8 using PCR-direct sequencing. P53 status and mutation site/type were correlated with nuclear protein accumulation, clinicopathologic variables and data on K-ras mutations and high-level microsatellite instability (MSI-H). We detected 96 P53 mutations in 87 (44.4%) cases and protein accumulation in 84 cases (42.8%). P53 mutations correlated directly with stage and inversely with MSI-H. Distal CRCs were more frequently mutated at major CpG hotspot codons [248 (8/66, 12.1%), 175 (7/66, 10.6%), and 245 (7/66, 10.6%)], while in proximal tumors codon 213, emerged as most frequently mutated (5/28, 17.9% vs. 3/66, 4.5%, P = 0.048). Transitions at CpGs, the most common mutation type, were more frequent in non-mucinous (25% vs. 10.4% in mucinous, P = 0.032), and distal CRC (27% vs. 12.5% in proximal, P = 0.02), and correlated with K-ras transversions. Transitions at non-CpGs, second most common P53 mutation, were more frequent in proximal tumors (15.6% vs. 4.7% in distal, P = 0.01), and correlated with K-ras transitions and MSI-H. Overall frequency and types of mutations and correlations with P53 accumulation, stage and MSI-H were as reported for non-Iranian patients. However P53 mutation site/type and correlations between P53 and K-ras mutation types differed between proximal and distal CRC. The codon 213 P53 mutation that recurred in proximal CRC was previously reported as frequent in esophageal cancer from Northern Iran.

KRASMutations As an Independent Prognostic Factor in Patients With Advanced Colorectal Cancer Treated With Cetuximab

Purpose

Cetuximab is efficient in advanced colorectal cancer (CRC). We previously showed that KRAS mutations were associated with resistance to cetuximab in 30 CRC patients. The aim of this study was to validate, in an independent larger series of 89 patients, the prognostic value of KRAS mutations on response to cetuximab and survival.

Patients and Methods

Eighty-nine metastatic CRC patients treated with cetuximab after treatment failure with irinotecan-based chemotherapy were analyzed for KRAS mutation by allelic discrimination on tumor DNA. The association between KRAS mutations and tumor response, skin toxicity, progression-free survival (PFS) and overall survival (OS) was analyzed.

Results

A KRAS mutation was present in 27% of the patients and was associated with resistance to cetuximab (0% v 40% of responders among the 24 mutated and 65 nonmutated patients, respectively; P < .001) and a poorer survival (median PFS: 10.1 v 31.4 weeks in patients without mutation; P = .0001; median OS: 10.1 v 14.3 months in patients without mutation; P = .026). When we pooled these 89 patients with patients from our previous study, the multivariate analysis showed that KRAS status was an independent prognostic factor associated with OS and PFS, whereas skin toxicity was only associated with OS. In a combined analysis, median OS times of patients with two, one, or no favorable prognostic factors (severe skin toxicity and no KRAS mutation) was of 15.6, 10.7, and 5.6 months, respectively.

Conclusion

These results confirm the high prognostic value of KRAS mutations on response to cetuximab and survival in metastatic CRC patients treated with cetuximab.

The alphaVbeta6 integrin as a novel molecular target for colorectal cancer

Recent advances in the treatment of colorectal cancer have resulted from a shift towards the use of molecular targeting strategies, with the identification of specific antigens critical for the development and progression of these tumors allowing the rational design of new therapeutic agents. The integrin receptor family provides very attractive targets for this 'magic bullet' approach, as they play key roles at all points during the malignant evolution of tumors, influencing growth, progression, angiogenesis and metastasis. One integrin in particular, alphaVbeta6, was recently shown to be upregulated in a model of colorectal tumor progression. Importantly, the consequences of this elevated receptor expression not only impact tumor cell function, but also indicate that alphaVbeta6 is a prognostic variable for colorectal cancer and one that is predictive of patient outcome in early-stage disease. Taken together with its normal expression pattern and known biologic functions, alphaVbeta6 thus emerges as a novel therapeutic candidate.

Clinical Implications of Our Advancing Knowledge of Colorectal Cancer Genetics: Inherited Syndromes, Prognosis, Prevention, Screening and Therapeutics

Recent genetic advances in our knowledge of colorectal cancer genetics are beginning to pay translational dividends in the management of this common clinical problem. We are now able to accurately screen and counsel individuals at risk of rare inherited cancer syndromes. We have recently introduced two of what are sure to be numerous biologic-based therapies, and have shown that colorectal neoplasia risk can be modestly reduced by various chemopreventative agents. Finally, our advancing knowledge has led to significant inroads into understanding what genetic alterations define prognosis and predict response to specific chemotherapeutic agents, and we are beginning to explore the utility of this knowledge in mass genetic-based clinical screening efforts. Enthusiasm must be tempered, however, by the extraordinary cost that often accompanies relatively modest gains. Finally, although genetic-based therapy often receives the greatest attention, molecular genetics, will likely have the greatest cost-effective impact in primary prevention and early diagnosis.

The MDM2 promoter polymorphism SNP309T-->G and the risk of uterine leiomyosarcoma, colorectal cancer, and squamous cell carcinoma of the head and neck

BACKGROUND

MDM2 acts as a principal regulator of the tumour suppressor p53 by targeting its destruction through the ubiquitin pathway. A polymorphism in the MDM2 promoter (SNP309) was recently identified. SNP309 was shown to result, via Sp1, in higher levels of MDM2 RNA and protein, and subsequent attenuation of the p53 pathway. Furthermore, SNP309 was proposed to be associated with accelerated soft tissue sarcoma formation in both hereditary (Li-Fraumeni) and sporadic cases in humans.

METHODS

We evaluated the possible contribution of SNP309 to three tumour types known to be linked with the MDM2/p53 pathway, using genomic sequencing or restriction fragment length polymorphism as screening methods. Three separate Finnish tumour materials (population based sets of 68 patients with early onset uterine leiomyosarcomas and 1042 patients with colorectal cancer, and a series of 162 patients with squamous cell carcinoma of the head and neck) and a set of 185 healthy Finnish controls were analysed for SNP309.

RESULTS

Frequencies of SNP309 were similar in all four cohorts. In the colorectal cancer series, SNP309 was somewhat more frequent in women and in patients with microsatellite stable tumours. Female SNP309 carriers were diagnosed with colorectal cancer approximately 2.7 years earlier than those carrying the wild type gene. However, no statistically significant association of SNP309 with patients' age at disease onset or to any other clinicopathological parameter was found in these three tumour materials.

CONCLUSION

SNP309 had no significant contribution to tumour formation in our materials. Possible associations of SNP309 with microsatellite stable colorectal cancer and with earlier disease onset in female carriers need to be examined in subsequent studies.

Prognostic effect of perioperative change of serum carcinoembryonic antigen level: a useful tool for detection of systemic recurrence in rectal cancer

BACKGROUND

The prognosis of patients even with the same stage of rectal cancer varies widely. We analyzed the capability of perioperative change of serum carcinoembryonic antigen (CEA) level for predicting recurrence and survival in rectal cancer patients.

METHODS

We reviewed 631 patients who underwent potentially curative resection for stage II or III rectal cancer. Patients were categorized into three groups according to their serum CEA concentrations on the seventh day before and on the seventh day after surgery: group A, normal CEA level (<or=5 ng/mL) in both periods; group B, increased preoperative and normal postoperative CEA; and group C, continuously increased CEA in both periods. The prognostic relevance of the CEA group was investigated by analyses of recurrence patterns and survival.

RESULTS

Stage III patients showed higher systemic recurrence (P = .001) and worse 5-year survival rates (P < .0001) for group C than for groups A and B. On multivariate analysis, the CEA group was a significant predictor for recurrence (P < .001; relative risk, 2.740; 95% confidence interval, 1.677-4.476) and survival (P = .001; relative risk, 2.174; 95% confidence interval, 1.556-3.308).

CONCLUSIONS

The perioperative serum CEA change was a useful prognostic indicator to predict for systemic recurrence and survival in stage III rectal cancer patients.

[Variation in the prognostic value of p53 protein in relation to tumoral stage in patients with colorectal adenocarcinoma]

OBJECTIVE

To analyze the prognostic value of p53 protein as a marker of recurrence risk in each tumoral stage.

PATIENTS AND METHOD

A prospective study of a cohort of 288 patients who underwent surgery for colorectal adenocarcinoma was performed. Stage 1 of the tumor-node-metastasis (TNM) classification was found in 42 patients (14.6%), stage II in 144 (50%) and stage III in 102 (35.4%). Histopathological variables were examined in tumor samples fixed in formol and embedded in paraffin and p53 (DO7 antibody) and proliferative cell nuclear antigen (PC-10 antibody) proteins were determined using immunohistochemistry. The results of p53 were analyzed in each of the categories of clinical and histopathological variables. Recurrence-free survival was calculated using the Kaplan-Meier method. The value of each variable as a predictive marker for tumoral recurrence was analyzed using Cox regression analysis. Hazard ratios and 95% confidence intervals were calculated as indicators of relative risk. The analysis was applied to the whole cohort and was subsequently repeated in each TNM tumoral stage separately.

RESULTS

Tumors with p53 protein overexpression more frequently recurred and showed lower recurrence-free survival at 5 years. However, the association between p53 expression and postoperative outcome was statistically significant in stage III tumors only. In this subgroup of patients, recurrence-free survival at 60 months was 60% in p53-negative tumors and was 26% in p53-positive tumors (p=0.010). In the multivariate analysis, p53 was an independent prognostic factor associated with a high risk of recurrence in stage III tumors (hazard ratio=2.76; 95% CI, 1.29-5.9; p=0.009). Overexpression of p53 showed prognostic value as a marker of high risk of recurrence in the form of metastases (hazard ratio=2.23; 95% CI, 1.04-4.75), but not as a prognostic marker of locoregional recurrence. No relationship was found between the state of p53 protein and the effect of postoperative adjuvant therapy.

CONCLUSION

The p53 protein does not have the same prognostic value in all tumoral stages. This protein is only predictive of high recurrence risk in the subgroup of patients with stage III tumors.

Tumor markers and colorectal cancer: utility in management

Colorectal cancer (CRC) is a leading cause of morbidity and mortality. Although genetic testing can screen for rare hereditary CRC syndromes, there is no ideal means of screening for sporadic forms of CRC. This review will focus on markers that are currently used in the management of sporadic CRC and their limitations, as well as possible future clinical applications.

Angiogenesis in human cancer: implications in cancer therapy

Angiogenesis represents an essential step in tumor proliferation, expansion, and metastasis. Tumor cells may express both proangiogenic and/or antiangiogenic factors. Under normal circumstances, angiogenesis is controlled through the equilibrium of these factors. This balance is disrupted in malignancy, resulting in promotion of angiogenesis. Among angiogenic molecules, VEGF appears to have a central role in the angiogenic process: it is the target of many proangiogenic factors, but it also regulates molecules that are implicated in endothelial proliferation. It has been suggested that VEGF may be a proximate angiogenic factor through which others act. The degree of angiogenesis and the expression of angiogenic factors have been associated with prognosis in several human neoplasms. In addition, angiogenesis offers a theoretically selective target for anticancer therapy, since it is only required for wound healing, endometrial proliferation, and pregnancy in healthy individuals. Antiangiogenic cancer treatment is still largely experimental and its clinical potential is currently being studied in clinical trials. Thalidomide, a drug with antiangiogenic properties, has shown significant efficacy in patients with relapsed or refractory multiple myeloma. In addition, an anti-VEGF monoclonal antibody prolonged survival in patients with advanced colorectal and renal cell carcinoma. Although these results are encouraging, selection of patients is essential in order to target populations most likely to benefit from antiangiogenic therapy.