Project description:This study aims to stratify stage II and III colon cancer patients for risk of disease recurrence based on DNA aberrations, including DNA copy number aberrations (CNA) and CNA-associated chromosomal breakpoints. To this end, high quality array-CGH data of clinically well-annotated colon cancer specimens was generated using FFPE material from a selected series of primary tumor and patient-matched normal tissue.
Project description:Background: Around 30% of all stage II colon cancer patients will relapse and die of their disease. At present no objective parameters for identification of high-risk stage II colon cancer patients, who will benefit from adjuvant chemotherapy, are established. With traditional histopathological features definition of high-risk stage II colon cancer patients is inaccurate. Therefore more objective and robust markers for prediction of relapse are needed. DNA copy number aberrations have proven to be robust prognostic markers, but have not been investigated for this specific group of patients. The aim of the present study is to identify chromosomal aberrations that can predict relapse of tumor in patients with stage II colon cancer. Materials and Methods: DNA was isolated from 40 formaldehyde fixed paraffin embedded stage II colon cancer samples with extensive clinicopathological data. Samples where hybridized using Comparative Genomic Hybridization (CGH) arrays to determine DNA copy number changes and microsatellite stability was determined by PCR. To analyze differences between stage II colon cancer patients with and without relapse of tumor a Wilcoxon rank-sum test was implemented with multiple testing correction Results: Patients with stage II colon cancer who had relapse of disease showed significant more losses on chromosome 4, 5, 15q, 17q and 18q. When microsatellite stable (MSS) patients were analyzed separately, only losses on chromosome 4q22.1-4q35.2 predicted worse outcome in stage II colon cancer patients. No differences in clinicopathological characteristics between patients with and without relapse were observed. Conclusion: Losses on 4q22.1-4q35.2 predict worse outcome in MSS stage II colon cancer patients and may aid in the selection of patients for adjuvant therapy.
Project description:Colorectal cancer is one of the most common cancers in the world. Histological staging is efficient but combination with molecular markers may improve tumors classification. Gene expression profiles have been defined as prognosis predictors among stage II and III tumors but their implementation in medical practice remains controversial. Stage-II tumors have been recognized as a heterogeneous group and high-risk morphologic features have been retained as justifying adjuvant chemotherapy. We propose here the investigation of clinical features and expression profiles from stage II and stage III colon carcinomas without DNA mismatch repair defect. A series of 130 colon cancer samples was retained. Expression profiles were established on oligonucleotide microarrays and processed in the R/Bioconductor environment. Hierarchical then supervised analyses were successively performed applying the data-sampling approach. A molecular signature of seven genes was found to cluster stage III tumors with an adjusted p-values lower than 10^-10. A subgroup of stage-II tumors aggregated this cluster in both series. No correlation was found between with the disease severity but the function of the discriminating genes suggests that tumors have been classified according to their putative response to adjuvant targeted or classic therapies. Further pharmacogenetic studies might document this observation.
Project description:The purpose of this study was to establish a new prognostic model for stage II/III colon cancer. Using public DNA microarray data of colon cancer patients, we created an integrated prognostic model for classifying the patients into high- and low-risk groups based on the expression levels of 55 genes and the KRAS mutation status. For validation, we examined specimens from patients with stage II/III colon cancer who had undergone radical resection at our department, and successfully confirmed prognostic value of our model. We believe that our prognostic model may be clinically helpful to select patients for adjuvant chemotherapy.
Project description:Purpose: The present study aimed to develop a classification model to predict recurrence in stage II and III colon cancer, using a previously published 128-gene signature on external and independent material. Experimental Design: Microarray gene expression data from 148 patients (37 Danish patients and 111 patients retrieved from the Gene Expression Omnibus, GSE17536) with stage II and III colon cancer were analyzed using Affymetrix Arrays (Affymetrix, Santa Clara, USA). Based on a known 128-gene signature, a classification model was created with the random forest method, using a training set consisting of stage I colon cancers (with localized disease and a good prognosis) and stage IV colon cancers (with metastasis and a poor prognosis). The classifier were built to predict stage II and III colon cancers as either stage I-like (good prognosis) or stage IV-like (poor prognosis). Results: The 3-year relapse-free survival probability (RFS) of stage III patients predicted to have a good prognosis was 79% compared to 55% of patients with a poor prognosis (P = 0.177, log-rank test). The classification model could not stratify stage II colon cancer. The complete dataset representing: (1) the 37 Danish patients (2) the 111 patients retrieved from Series GSE17536 (re-used data), is linked below as a supplementary file. Tumor samples were obtained from 37 patients with stage II and III colon cancer, who underwent colon resection at the Department of Surgery, Roskilde Hospital, Denmark and the Department of Surgery, Bispebjerg Hospital, Denmark between 2001 and 2008. Purified tumor RNA was reverse-transcribed, labelled and hybridized to Affymetrix Human Genome U133 Plus 2.0 GeneChip Array (Affymetrix, Santa Clara, USA) according to the manufacturers instructions and scanned at the RH Microarray Center, Rigshospitalet, University of Copenhagen.
Project description:Background: Around 30% of all stage II colon cancer patients will relapse and die of their disease. At present no objective parameters for identification of high-risk stage II colon cancer patients, who will benefit from adjuvant chemotherapy, are established. With traditional histopathological features definition of high-risk stage II colon cancer patients is inaccurate. Therefore more objective and robust markers for prediction of relapse are needed. DNA copy number aberrations have proven to be robust prognostic markers, but have not been investigated for this specific group of patients. The aim of the present study is to identify chromosomal aberrations that can predict relapse of tumor in patients with stage II colon cancer. Materials and Methods: DNA was isolated from 40 formaldehyde fixed paraffin embedded stage II colon cancer samples with extensive clinicopathological data. Samples where hybridized using Comparative Genomic Hybridization (CGH) arrays to determine DNA copy number changes and microsatellite stability was determined by PCR. To analyze differences between stage II colon cancer patients with and without relapse of tumor a Wilcoxon rank-sum test was implemented with multiple testing correction Results: Patients with stage II colon cancer who had relapse of disease showed significant more losses on chromosome 4, 5, 15q, 17q and 18q. When microsatellite stable (MSS) patients were analyzed separately, only losses on chromosome 4q22.1-4q35.2 predicted worse outcome in stage II colon cancer patients. No differences in clinicopathological characteristics between patients with and without relapse were observed. Conclusion: Losses on 4q22.1-4q35.2 predict worse outcome in MSS stage II colon cancer patients and may aid in the selection of patients for adjuvant therapy. 40 Stage II colorectal cancer (CRC) tissue samples (FFPE), 16 with and 24 without relapse of tumor
Project description:Colorectal cancer is one of the most common cancers in the world. Histological staging is efficient but combination with molecular markers may improve tumors classification. Gene expression profiles have been defined as prognosis predictors among stage II and III tumors but their implementation in medical practice remains controversial. Stage-II tumors have been recognized as a heterogeneous group and high-risk morphologic features have been retained as justifying adjuvant chemotherapy. We propose here the investigation of clinical features and expression profiles from stage II and stage III colon carcinomas without DNA mismatch repair defect. A series of 130 colon cancer samples was retained. Expression profiles were established on oligonucleotide microarrays and processed in the R/Bioconductor environment. Hierarchical then supervised analyses were successively performed applying the data-sampling approach. A molecular signature of seven genes was found to cluster stage III tumors with an adjusted p-values lower than 10^-10. A subgroup of stage-II tumors aggregated this cluster in both series. No correlation was found between with the disease severity but the function of the discriminating genes suggests that tumors have been classified according to their putative response to adjuvant targeted or classic therapies. Further pharmacogenetic studies might document this observation. Expression profile of stage-II colon carcinomas distinguishes two patterns of tumors based on a 7-gene signature. One pattern is very similar to that of stage-III tumors and the corresponding tumors aggregate into a single cluster. Genes function suggests possible tumor determinism in drug response more than in prognosis evolution.
Project description:Chromosomal instable colorectal cancer is marked by specific large chromosomal copy number aberrations. Recently, focal aberrations of 3Mb or smaller have been identified as a common phenomenon in cancer. Inherent to their limited size, these aberrations harbour one or few genes. The aim of this study is to identify recurrent focal chromosomal aberrations and their candidate driver genes in a well defined series of stage II colon cancers and assess their potential clinical relevance. High resolution DNA copy number profiles were obtained from 38 formalin fixed paraffin embedded colon cancer samples with matched normal mucosa as a reference using array comparative genomic hybridization. In total, 81 focal chromosomal aberrations were identified that harboured 177 genes. Statistical validation of focal aberrations and identification of candidate driver genes was performed by enrichment analysis and mapping copy number and mutation data of colorectal-, breast-, pancreatic cancer and glioblastomas to loci of focal aberrations in stage II colon cancer. This analysis demonstrated a significant overlap with previously identified focal amplifications in colorectal cancer, but not with cancers from other sites. In contrast, focal deletions seem less tumour type specific since they also show significant overlap with focal deletions of other sites. Focal deletions detected are significantly enriched for cancer genes and genes frequently mutated in colorectal cancer. The mRNA expression of these genes is significantly correlated with DNA copy number status, supporting the relevance of focal aberrations. Loss of 5q34 and gain of 13q22.1 were identified as independent prognostic factors of survival in this series of patients. In conclusion, focal chromosomal copy number aberrations in stage II colon cancer are enriched in cancer genes which contribute to and drive the process of colorectal cancer development. DNA copy number status of these genes correlate with mRNA expression and some are associated with clinical outcome. 38 Stage II colorectal cancer (CRC) tissue samples (FFPE) of which 19 were done on expression arrays. One sample (Stage II colorectal cancer tissue samples (FFPE) 26) was also done on the 135K NimbleGen array. Fresh frozen and FFPE of the same CRC stage I sample was done on 105K agilent. The fresh frozen was across array in silico set out against a pool of blood of 18 healthy females.