Molecular characterization of circulating colorectal tumor cells defines genetic signatures for individualized cancer care.

Studies on circulating tumor cells (CTCs) have largely focused on platform development and CTC enumeration rather than on the genomic characterization of CTCs. To address this, we performed targeted sequencing of CTCs of colorectal cancer patients and compared the mutations with the matched primary tumors. We collected preoperative blood and matched primary tumor samples from 48 colorectal cancer patients. CTCs were isolated using a label-free microfiltration device on a silicon microsieve. Upon whole genome amplification, we performed amplicon-based targeted sequencing on a panel of 39 druggable and frequently mutated genes on both CTCs and fresh-frozen tumor samples. We developed an analysis pipeline to minimize false-positive detection of somatic mutations in amplified DNA. In 60% of the CTC-enriched blood samples, we detected primary tumor matching mutations. We found a significant positive correlation between the allele frequencies of somatic mutations detected in CTCs and abnormal CEA serum level. Strikingly, we found driver mutations and amplifications in cancer and druggable genes such as APC, KRAS, TP53, ERBB3, FBXW7 and ERBB2. In addition, we found that CTCs carried mutation signatures that resembled the signatures of their primary tumors. Cumulatively, our study defined genetic signatures and somatic mutation frequency of colorectal CTCs. The identification of druggable mutations in CTCs of preoperative colorectal cancer patients could lead to more timely and focused therapeutic interventions.

Metformin Inhibits Cellular Proliferation and Bioenergetics in Colorectal Cancer Patient-Derived Xenografts.

There is increasing preclinical evidence suggesting that metformin, an antidiabetic drug, has anticancer properties against various malignancies, including colorectal cancer. However, the majority of evidence, which was derived from cancer cell lines and xenografts, was likely to overestimate the benefit of metformin because these models are inadequate and require supraphysiologic levels of metformin. Here, we generated patient-derived xenograft (PDX) lines from 2 colorectal cancer patients to assess the properties of metformin and 5-fluorouracil (5-FU), the first-line drug treatment for colorectal cancer. Metformin (150 mg/kg) as a single agent inhibits the growth of both PDX tumors by at least 50% (P < 0.05) when administered orally for 24 days. In one of the PDX models, metformin given concurrently with 5-FU (25 mg/kg) leads to an 85% (P = 0.054) growth inhibition. Ex vivo culture of organoids generated from PDX demonstrates that metformin inhibits growth by executing metabolic changes to decrease oxygen consumption and activating AMPK-mediated pathways. In addition, we also performed genetic characterizations of serial PDX samples with corresponding parental tissues from patients using next-generation sequencing (NGS). Our pilot NGS study demonstrates that PDX represents a useful platform for analysis in cancer research because it demonstrates high fidelity with parental tumor. Furthermore, NGS analysis of PDX may be useful to determine genetic identifiers of drug response. This is the first preclinical study using PDX and PDX-derived organoids to investigate the efficacy of metformin in colorectal cancer. Mol Cancer Ther; 16(9); 2035-44. ©2017 AACR.

Tumor-derived circulating endothelial cell clusters in colorectal cancer.

Clusters of tumor cells are often observed in the blood of cancer patients. These structures have been described as malignant entities for more than 50 years, although their comprehensive characterization is lacking. Contrary to current consensus, we demonstrate that a discrete population of circulating cell clusters isolated from the blood of colorectal cancer patients are not cancerous but consist of tumor-derived endothelial cells. These clusters express both epithelial and mesenchymal markers, consistent with previous reports on circulating tumor cell (CTC) phenotyping. However, unlike CTCs, they do not mirror the genetic variations of matched tumors. Transcriptomic analysis of single clusters revealed that these structures exhibit an endothelial phenotype and can be traced back to the tumor endothelium. Further results show that tumor-derived endothelial clusters do not form by coagulation or by outgrowth of single circulating endothelial cells, supporting a direct release of clusters from the tumor vasculature. The isolation and enumeration of these benign clusters distinguished healthy volunteers from treatment-naïve as well as pathological early-stage (≤IIA) colorectal cancer patients with high accuracy, suggesting that tumor-derived circulating endothelial cell clusters could be used as a means of noninvasive screening for colorectal cancer. In contrast to CTCs, tumor-derived endothelial cell clusters may also provide important information about the underlying tumor vasculature at the time of diagnosis, during treatment, and throughout the course of the disease.

Asia Pacific Consensus Statements on Crohn's disease. Part 1: Definition, diagnosis, and epidemiology: (Asia Pacific Crohn's Disease Consensus--Part 1).

Inflammatory bowel disease (IBD) was previously thought to be rare in Asia, but emerging data indicate rising incidence and prevalence of IBD in the region. The Asia Pacific Working Group on Inflammatory Bowel Disease was established in Cebu, Philippines, at the Asia Pacific Digestive Week conference in 2006 under the auspices of the Asian Pacific Association of Gastroenterology with the goal of developing best management practices, coordinating research, and raising awareness of IBD in the region. The consensus group previously published recommendations for the diagnosis and management of ulcerative colitis with specific relevance to the Asia-Pacific region. The present consensus statements were developed following a similar process to address the epidemiology, diagnosis, and management of Crohn's disease. The goals of these statements are to pool the pertinent literature specifically highlighting relevant data and conditions in the Asia-Pacific region relating to the economy, health systems, background infectious diseases, differential diagnoses, and treatment availability. It does not intend to be all comprehensive and future revisions are likely to be required in this ever-changing field.

Asia-Pacific consensus statements on Crohn's disease. Part 2: Management.

The Asia Pacific Working Group on Inflammatory Bowel Disease was established in Cebu, Philippines, at the Asia Pacific Digestive Week conference in 2006 under the auspices of the Asian Pacific Association of Gastroenterology (APAGE) with the goal of developing best management practices, coordinating research and raising awareness of IBD in the region. The consensus group previously published recommendations for the diagnosis and management of ulcerative colitis (UC) with specific relevance to the Asia-Pacific region. The present consensus statements were developed following a similar process to address the epidemiology, diagnosis and management of Crohn's disease (CD). The goals of these statements are to pool the pertinent literature specifically highlighting relevant data and conditions in the Asia-Pacific region relating to the economy, health systems, background infectious diseases, differential diagnoses and treatment availability. It does not intend to be all-comprehensive and future revisions are likely to be required in this ever-changing field.

Prevalence of KRAS, BRAF, PI3K and EGFR mutations among Asian patients with metastatic colorectal cancer.

Mutations in oncogenes along the epidermal growth factor receptor (EGFR) signaling pathway have been implicated in the resistance to cetuximab in patients with metastatic colorectal cancer (mCRC). However, the relative significance of these mutations based on their frequencies of occurrence in the Singaporean population remains unclear. In the present study, the prevalence of Kirsten rat sarcoma viral oncogene homolog (KRAS), v-Raf murine sarcoma viral oncogene homolog B (BRAF), phosphoinositide 3-kinase (PI3K) and EGFR somatic mutations were determined among Singaporean patients with mCRC. DNA extracted from 45 pairs of surgically resected tumor and normal mucosa samples was subjected to direct sequencing or restriction fragment length polymorphism. Associations of the genetic mutations with various clinicopathological parameters were further explored. Mutations in either codon 12 or 13 of KRAS were confirmed as prominent phenomena among the included Singaporean mCRC patients, at a prevalence comparable with that of Caucasian and patients of other Asian ethnicities [33.3% (90% confidence interval, 21.8-44.9%)]. KRAS mutation was not associated with clinicopathological features, including age, gender and ethnicity of patients, or the tumor site, differentiation and mucinous status. Conversely, the prevalence of BRAF (0%), PI3K (2.2%) and EGFR (0%) mutations were low. The results of the present study indicate that KRAS mutations are prevalent among the studied population, and confirm the low prevalence of BRAF, PI3K and EGFR mutations. KRAS should be prioritized as an investigational gene for future studies of predictive biomarkers of cetuximab response among Singaporean patients with mCRC.

Non-invasive sensitive detection of KRAS and BRAF mutation in circulating tumor cells of colorectal cancer patients.

Characterization of genetic alterations in tumor biopsies serves as useful biomarkers in prognosis and treatment management. Circulating tumor cells (CTCs) obtained non-invasively from peripheral blood could serve as a tumor proxy. Using a label-free CTC enrichment strategy that we have established, we aimed to develop sensitive assays for qualitative assessment of tumor genotype in patients. Blood consecutively obtained from 44 patients with local and advanced colorectal cancer and 18 healthy donors were enriched for CTCs using a size-based microsieve technology. To screen for CTC mutations, we established high-resolution melt (HRM) and allele-specific PCR (ASPCR) KRAS-codon 12/13- and BRAF-codon 600- specific assays, and compared the performance with pyrosequencing and Sanger sequencing. For each patient, the resulting CTC genotypes were compared with matched tumor and normal tissues. Both HRM and ASPCR could detect as low as 1.25% KRAS- or BRAF-mutant alleles. HRM detected 14/44 (31.8%) patients with KRAS mutation in CTCs and 5/44 (11.3%) patients having BRAF mutation in CTCs. ASPCR detected KRAS and BRAF mutations in CTCs of 10/44 (22.7%) and 1/44 (2.3%) patients respectively. There was an increased detection of mutation in blood using these two methods. Comparing tumor tissues and CTCs mutation status using HRM, we observed 84.1% concordance in KRAS genotype (p = 0.000129, Fishers' exact test; OR = 38.7, 95% CI = 4.05-369) and 90.9% (p = 0.174) concordance in BRAF genotype. Our results demonstrate that CTC enrichment, coupled with sensitive mutation detection methods, may allow rapid, sensitive and non-invasive assessment of tumor genotype.

Global fecal microRNA profiling in the identification of biomarkers for colorectal cancer screening among Asians.

Fecal microRNAs (miRNAs) are increasingly explored as non-invasive markers of colorectal cancer (CRC). However, its holistic profile in Asian CRC patients remains elusive. In the present study, the global human fecal miRNAs in Asian Chinese CRC patients was assayed to elucidate novel diagnostic fecal markers. Additionally, the influence of blood in stool on fecal miRNA levels was investigated for the first time. Microarray analysis was applied to profile the fecal miRNAs extracted from CRC patients and healthy subjects. Concurrently, surgically resected tumor and matched normal mucosae were analyzed. Potential fecal miRNA markers were further confirmed using real-time PCR in 17 CRC patients and 28 healthy subjects. Global miRNA profiling uncovered 17 fecal markers (p<0.05) differentially regulated in CRC. Fecal miR-223 and miR-451 represented robust markers in distinguishing CRC patients from healthy subjects, as evident from areas under the receiver operator characteristic curves of 0.939 and 0.971, respectively. Blood in stool affected fecal miR-451, miR-223 and miR-135b levels to a varying extent and substantially impacted the interpretation of the clinical data. Notably, a discrete set of aberrant miRNAs occurred within the tumor, indicating the presence of contributors beyond the exfoliation of tumor cells to the fecal miRNA profile. In summary, the utility of a global miRNA screening approach was successfully demonstrated in elucidating diagnostic markers of CRC. In particular, fecal miR-223 and miR-451 hold promise in detecting CRC.

Systematic study on genetic and epimutational profile of a cohort of Amsterdam criteria-defined Lynch Syndrome in Singapore.

BACKGROUND: Germline defects of mismatch repair (MMR) genes underlie Lynch Syndrome (LS). We aimed to gain comprehensive genetic and epigenetic profiles of LS families in Singapore, which will facilitate efficient molecular diagnosis of LS in Singapore and the region. METHODS: Fifty nine unrelated families were studied. Mutations in exons, splice-site junctions and promoters of five MMR genes were scanned by high resolution melting assay followed by DNA sequencing, large fragment deletions/duplications and promoter methylation in MLH1, MSH2, MSH6 and PMS2 were evaluated by multiplex ligation-dependent probe amplification. Tumor microsatellite instability (MSI) was assessed with five mononucleotide markers and immunohistochemical staining (IHC) was also performed. RESULTS: Pathogenic defects, all confined to MLH1 and MSH2, were identified in 17 out of 59 (28.8%) families. The mutational spectrum was highly heterogeneous and 28 novel variants were identified. One recurrent mutation in MLH1 (c.793C>T) was also observed. 92.9% sensitivity for indication of germline mutations conferred by IHC surpassed 64.3% sensitivity by MSI. Furthermore, 15.6% patients with MSS tumors harbored pathogenic mutations. CONCLUSIONS: Among major ethnic groups in Singapore, all pathogenic germline defects were confined to MLH1 and MSH2. Caution should be applied when the Amsterdam criteria and consensus microsatellite marker panel recommended in the revised Bethesda guidelines are applied to the local context. We recommend a screening strategy for the local LS by starting with tumor IHC and the hotspot mutation testing at MLH1 c.793C>T followed by comprehensive mutation scanning in MLH1 and MSH2 prior to proceeding to other MMR genes.

Non-invasive fecal metabonomic detection of colorectal cancer.

Colorectal cancer (CRC) is a major cause of mortality in many developed countries. Effective screening strategies were called for to facilitate timely detection and to promote a better clinical outcome. In this study, the role of fecal metabonomics in the non-invasive detection of CRC was investigated. Gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) was utilized for the metabolic profiling of feces obtained from 11 CRC patients and 10 healthy subjects. Concurrently, matched tumor and normal mucosae surgically excised from CRC patients were profiled. CRC patients were differentiated clearly from healthy subjects based on their fecal metabonomic profiles (orthogonal partial least squares discriminant analysis [OPLS-DA], 1 predictive and 3 Y-orthogonal components, R (2)X = 0.373, R (2)Y = 0.995, Q (2) [cumulative] = 0.215). The robustness of the OPLS-DA model was demonstrated by an area of 1 under the receiver operator characteristic curve. OPLS-DA revealed fecal marker metabolites (e.g., fructose, linoleic acid, and nicotinic acid) that provided novel insights into the tumorigenesis of CRC. Interestingly, a disparate set of CRC-related metabolic aberrations occurred at the tissue level, implying the contribution of processes beyond the direct shedding of tumor cells to the fecal metabotype. In summary, this work established proof-of-principle for GC/TOFMS-based fecal metabonomic detection of CRC and offered new perspectives on the underlying mechanisms.

A novel indel in exon 9 of APC upregulates a 'skip exon 9' isoform and causes very severe familial adenomatous polyposis.

Germline mutation in the adenomatous polyposis coli (APC) gene causes the majority (80%) of familial adenomatous polyposis (FAP), an autosomal dominantly inherited form of colorectal cancer (CRC). Mutation in 5'end of exon 9 of APC usually results in an attenuated form of FAP (aFAP), characterized by later age of onset and fewer polyps. The presence of exon 9a, an in-frame isoform with exon 8 spliced to 3'end of exon 9, modulates any deleterious effect of the mutation. A third lowly expressed isoform that completely skips exon 9 is present in both healthy individuals and FAP patients. We report here an interesting case of a proband with an APC mutation in 5'end of exon 9 that presented with six synchronous advanced CRCs at age 37. The novel insertion-deletion (indel) at codon 409, c.1226-1229delTTTTinsAAA, caused upregulation of the 'skip exon 9' isoform, r934-1312del, resulting in a premature stop codon at exon 10 and a truncated protein that removed all of the ß-catenin (CTNNB1) binding motifs, thus activating the downstream T-cell transcription factor (Tcf) pathway. Exon 9a isoform was concomitantly downregulated. This finding emphasizes the necessity of examining the various isoforms of exon 9 to avoid clinical mismanagement and counseling based on just the mutation site by genomic DNA sequencing alone.

Global gas chromatography/time-of-flight mass spectrometry (GC/TOFMS)-based metabonomic profiling of lyophilized human feces.

Gas chromatography mass spectrometry (GC/MS)-based fecal metabonomics represents a powerful systems biology approach for elucidating metabolic biomarkers of lower gastrointestinal tract (GIT) diseases. Unlike metabolic profiling of fecal water, the profiling of complete fecal material remains under-explored. Here, a gas chromatography/time-of-flight mass spectrometry (GC/TOFMS) method was developed and validated for the global metabonomic profiling of human feces. Fecal and fecal water metabotypes were also profiled and compared. Additionally, the unclear influence of blood in stool on the fecal metabotype was investigated unprecedentedly. Eighty milligram of lyophilized feces was ultrasonicated with 1mL of methanol:water (8:2) for 30min, followed by centrifugation, drying of supernatant, oximation and trimethylsilylation for 45min. Lyophilized feces demonstrated a more comprehensive metabolic coverage than fecal water, based on the number of chromatographic peaks. Principal component analysis (PCA) indicated occult blood (1mgHb/g feces) exerted a negligible effect on the fecal metabotype. Conversely, a unique metabotype related to feces spiked with gross blood (100mgHb/g feces) was revealed (PCA, R(2)X=0.837, Q(2)=0.794), confirming the potential confounding effect of gross GIT bleeding on the fecal metabotype. This pertinent finding highlights the importance of prudent interpretation of fecal metabonomic data, particularly in GIT diseases where bleeding is prevalent.

Mismatch repair deficiency screening via immunohistochemical staining in young Asians with colorectal cancers.

BACKGROUND: The incidence of mismatch repair deficiency in colorectal cancer (CRC) in young people remains unknown in Asians. The present study assessed the clinicopathological features and efficacy of immunohistochemistry screening for Lynch syndrome in young Asian CRC patients. MATERIAL AND METHODS: This was a retrospective review conducted in Singapore General Hospital between January 2006 and December 2010 of 240 unrelated patients under the age of 50. All patients had immunohistochemical (IHC) staining for mismatch repair proteins in resected CRC specimen data retrieved from a prospective computerized database. RESULTS: A total of 21 % (n = 51) of the patients had abnormal IHC staining. Loss of staining for MLH1, MSH2, MSH6, and PMS2 proteins was observed in 10, 4, 6, and 13 % of tumors, respectively. Of the 22 patients who had abnormal staining of MLH1, 13 had concomitant abnormal staining for PMS2. One tumor specimen had abnormal staining in all four proteins. If the Amsterdam criteria alone were to be used, 86 % (n = 44) of the cohort would have not been detected for mismatch repair gene defects. CONCLUSIONS: The overall burden of germline mismatch repair deficiency in the Singapore population may be as high as 21 %. The Amsterdam criteria alone are inadequate to detect Lynch syndrome patients. The use of IHC staining of at least four mismatch repair proteins is a useful screening strategy for Lynch syndrome diagnosis. Routine screening of mismatch repair deficiency may be recommended for all young Asian CRC patients.

Investigating the role of nucleoside transporters in the resistance of colorectal cancer to 5-fluorouracil therapy.

Resistance to 5-fluorouracil (5FU) poses a constant challenge to the management of colorectal cancer (CRC). Consistent efforts were called for to identify molecular markers that can effectively predict patients' response. This study investigated the role of nucleoside transporters, particularly human equilibrative nucleoside transporter 1 (hENT1), in predicting clinical treatment outcome with 5FU-based therapy. Expression of a panel of nucleoside transporters in biopsied tumors from 7 CRC patients was measured by real-time PCR prior to 5FU-based chemotherapy. To provide mechanistic support for the role of hENT1 in 5FU resistance, cell viability of Caco-2 cells was measured, following incubation with varying concentrations of 5FU and a hENT1 inhibitor. Biopsied tumors were further subjected to global metabonomic profiling using gas chromatography/mass spectrometry. High hENT1 levels in tumor tissue correlated with poor clinical response to 5FU. Corroborating with the clinical findings, chemical inhibition of hENT1 in Caco-2 cells resulted in an augmentation of 5FU efficacy. Metabonomic profiling revealed that the pretreatment metabotype associated with non-responders to 5FU therapy was distinct from metabotype of responders (partial least-squares discriminant analysis Q(2) (cumulative) = 0.898, R(2)X = 0.513, R(2)Y = 0.996). This is the first clinical report on the relationships of intratumoral expression of nucleoside transporters and tumor metabotype with response to 5FU among CRC patients. Coupled to the in vitro findings, our preliminary data suggested hENT1 to be a potential codeterminant of clinical response to 5FU.

Localized gastrointestinal stromal tumor of the rectum: An uncommon primary site with prominent disease and treatment-related morbidities.

Well-established clinicopathological variables used in the risk stratification of gastrointestinal stromal tumor (GIST) may not completely predict rectal GIST, an uncommon and poorly studied GIST subset. The aim of the present study was to determine the patterns of relapse and morbidities associated with recurrence in rectal GIST. A single-institution retrospective study between 2002 and 2011 was conducted, identifying 9 patients (8%) with localized rectal GIST, while comparing small intestinal (n=37) and gastric (n=63) GIST (median age, 60 years). Rectal GIST tumors were smaller compared to small intestinal/gastric GIST (P=0.044). The number of mitoses per 50 high-power field (HPF) did not differ by primary site. In general, 73% of patients were high-risk, as defined by the National Institutes of Health (NIH) consensus criteria, however, only 25% received adjuvant imatinib. Fewer rectal GIST patients achieved negative surgical margins compared to small intestinal/gastric GIST (67 vs. 92%; P=0.054). Of the 9 patients with localized rectal GIST 6 had peri-operative tumor rupture, anastomotic breakdown or required anal sphincter-compromising surgery. At the time of the first relapse, 83% of the recurrences were local failures for rectal GIST, compared to 21% for small intestinal/gastric GIST (P=0.005). The median relapse-free survival was 51 months for the entire cohort, and 54, 36 and 56 months for rectal, small intestinal and gastric GIST, respectively (P=0.468). Rectal GIST was found to be associated with high rates of local relapse and significant morbidity, despite being significantly smaller compared to GIST of other sites. A multimodality peri-operative therapeutic approach may be required to improve outcomes.

Association of Caucasian-identified variants with colorectal cancer risk in Singapore Chinese.

BACKGROUND: Genome-wide association studies (GWAS) in Caucasians have identified fourteen index single nucleotide polymorphisms (iSNPs) that influence colorectal cancer (CRC) risk. METHODS: We investigated the role of eleven iSNPs or surrogate SNPs (sSNPs), in high linkage disequilibrium (LD, r(2)≥ 0.8) and within 100 kb vicinity of iSNPs, in 2,000 age- and gender-matched Singapore Chinese (SCH) cases and controls. RESULTS: Only iSNP rs6983267 at 8q24.21 and sSNPs rs6695584, rs11986063, rs3087967, rs2059254, and rs7226855 at 1q41, 8q23.3, 11q23.1, 16q22.1 and 18q21.1 respectively showed evidence of association with CRC risk, with odds ratios (OR) ranging from 1.13 to 1.40. sSNP rs827401 at 10p14 was associated with rectal cancer risk (OR = 0.74, 95% CI 0.63-0.88) but not disease prognosis (OR = 0.91, 95% CI 0.69-1.20). Interestingly, sSNP rs3087967 at 11q23.1 was associated with CRC risk in men (OR = 1.34, 95% CI 1.14-1.58) but not women (OR = 1.07, 95% CI: 0.88-1.29), suggesting a gender-specific role. Half of the Caucasian-identified variants, including the recently fine-mapped BMP pathway loci, BMP4, GREM1, BMP2 and LAMA 5, did not show any evidence for association with CRC in SCH (OR ~1; p-value >0.1). Comparing the results of this study with that of the Northern and Hong Kong Chinese, only variants at chromosomes 8q24.21, 10p14, 11q23.1 and 18q21.1 were replicated in at least two out of the three Chinese studies. CONCLUSIONS: The contrasting results between Caucasians and Chinese could be due to different LD patterns and allelic frequencies or genetic heterogeneity. The results suggest that additional common variants contributing to CRC predisposition remained to be identified.

Metabotyping of human colorectal cancer using two-dimensional gas chromatography mass spectrometry.

Colorectal cancer (CRC) is the fourth most common cause of death from cancer in the world. The limitations of the currently available methods and biomarkers for CRC management highlight the necessity of finding novel markers. Metabonomics can be used to search for potential markers that can provide molecular insight into human CRC. The emergence of two-dimensional gas chromatography time of flight mass spectrometry (GC × GC/TOFMS) has comprehensively enhanced the metabolic space coverage of conventional GC/MS. In this study, a GC × GC/TOFMS was developed for the tissue-based global metabonomic profiling of CRC. A Pegasus GC × GC/TOFMS (Leco Corp., St. Joseph, MI, USA) system comprising an Agilent 7890 GC and Pegasus IV TOFMS was used for this purpose. An Agilent DB-1 (30 m × 250 µm × 0.25 µm) fused silica capillary column and a Restek Rxi®-17 (1 m × 100 µm × 0.10 µm) fused silica capillary column were used as the primary and secondary columns, respectively. The method was applied for global metabonomic profiling of matched CRC and normal tissues (n = 63) obtained from 31 CRC patients during surgery. An attempt was also made to compare GC × GC/TOFMS with GC/MS and NMR in similar application. The results showed that the metabotype associated with CRC is distinct from that of normal tissue and led to the identification of chemically diverse marker metabolites. Metabolic pathway mapping suggested deregulation of various biochemical processes such as glycolysis, Krebs cycle, osmoregulation, steroid biosynthesis, eicosanoid biosynthesis, bile acid biosynthesis, lipid, amino acid and nucleotide metabolism.

Predictive genetic testing of first degree relatives of mutation carriers is a cost-effective strategy in preventing hereditary non-polyposis colorectal cancer in Singapore.

Colorectal cancer (CRC) is the most common cancer in Singapore. We sought to evaluate the long-term cost-effectiveness of targeted genetic testing and surveillance programs in individuals at high risk of hereditary non-polyposis colorectal cancer (HNPCC), as compared to an unselective clinical surveillance program alone in Singapore. A Markov model analysis from the healthcare service provider's perspective was developed to follow over a lifetime a cohort of cancer-free 21-year-old individuals, who were first-degree relatives of HNPCC patients with a known mutation. Genetic testing strategy provided a lifetime saving of Singapore dollars (SGD) 13,588 per person and gained additional life years of 0.01, as compared to clinical surveillance alone, by sparing non-mutation carriers from unnecessary and invasive intensive clinical surveillance (assuming 100% compliance with recommended surveillance programs in both strategies). Sensitivity analyses showed that as long as the compliance rate in mutation carriers was not lower than that for individuals without genetic testing, pursuing a genetic testing strategy would either be a more favorable option with discounted incremental cost-effectiveness ratios ranging from SGD 6,961 to 17,289 per life year gained or a dominant status achieved (more life year gained and less costly). Genetic testing for individuals at high risk of HNPCC allows targeted clinical surveillance to be directed at mutation carriers, ensuring efficient use of healthcare resources and reduces CRC-related mortality. It can be regarded as a cost-effective strategy in Singapore, if an improved compliance with recommended surveillance protocol is achieved in proven mutation carriers.

Stage IV colorectal cancers: an analysis of factors predicting outcome and survival in 728 cases.

INTRODUCTION: Stage IV colorectal cancer (CRC) is a heterogeneous disease with many treatment options. The optimum management algorithm is yet to be established. The aim of this study was to evaluate the prognostic factors of survival and to determine the operative benefit of resection of the primary tumour followed by chemotherapy. METHODS: Seven hundred twenty-eight consecutive patients who presented with stage IV CRC from 1999 to 2007 were identified. The demographics and clinicopathological characteristics of these patients were reviewed. Survival curves were constructed using the Kaplan-Meier method. Multivariate analysis assessed independent prognostic factors. RESULTS: In the surgical management of the primary, 79% (n = 572) were performed electively, 18% (n = 134) as an emergency procedure and 3% (n = 22) did not have any surgery. Twelve percent (n = 78) had a permanent stoma. Major morbidity was 4.3% (n = 31), and 30-day mortality was low at 6% (n = 46). Ten percent (n = 71) had a subsequent metasectomy. Patients who underwent curative resections tended to be female (p = 0.05), of a younger age group (age, ≤ 50; p = 0.005), as well as had better haemoglobin (p = 0.0001) and albumin levels (p = 0.0001). For the study cohort, the cancer-specific survival (CSS) at 1 year was 47.9% [95% confidence interval (CI), 44.2-51.6%], 3-year CSS was 10.8% (95% CI, 3.3-13.3%) and 5-year CSS was 7.0% (95% CI, 4.8-9.2%). CSS was significantly higher in patients that underwent colonic resection. In cases where resection of the primary was possible, multivariate analysis revealed that CEA value >40 ng/ml, low albumin levels ≤ 34 g/l, poorly differentiated tumours, advanced tumour stage (T3/T4), nodal disease (N1/N2) and presence of diffuse metastasis were all significant factors associated with poorer cancer-specific survival. CONCLUSION: This study has shown a good survival benefit in stage IV CRC when an aggressive policy of primary resection is adopted. Resection of metastases with curative intent should be performed whenever possible.