Population Of Colorectal Cancer Patients Research Articles

Differences in Colorectal Cancer (CRC) patients who did and did not undergo screening

Abstract Background The Australian National Bowel Cancer Screening Program (NBSCP) is a free population-based screening program which aims to identify precancerous lesions and early colorectal cancer (CRC) using an immunochemical faecal occult blood test in average risk Australians. Formally commencing in 2006, NBCSP participation rate in eligible 50-74-year-old people was 42% in 2018. The barriers and facilitators of participation in the NBCSP have been explored for the general, at-risk population but not in a population of CRC patients. This is the first study to assess a population of CRC patients, post diagnosis, who would have been eligible for CRC screening to determine the barriers and facilitators to screening. Methods A cross sectional study nested within a cohort study. Data from CRC patients who participated in the 45 and Up Study; the largest cohort study in Australia and southern hemisphere, were analysed to compare those who had and had not participated in CRC screening. Logistic regression analyses were conducted using RStudio (version 3.5.2, Boston, Massachusetts, USA.). Multiple Imputation (MI), was used to handle missing values assumed to be missing at random. Results A total of 339 CRC patients were included. Patients who were female, overweight (≥25kg/m2), consumed less than the recommended five servings of vegetables per day, consumed less than or equal to fourteen standard drinks per week (compared to non-drinkers) or did not meet physical activity guidelines were significantly less likely to have participated in screening. Conclusions Our study has taken a unique approach to identifying a high-risk group by exploring factors to screening participation in CRC patients. CRC patients with less healthy lifestyles were less likely to participate in screening. In contrast to previous studies, female patients were less likely to participate in screening than males were. This was an unexpected finding and should be replicated. Key messages Not surprising that those with less healthy lifestyle practices also reflected less than ideal screening practices. Surprising that female patients participated less in screening than males. Future interventions to improve CRC screening participation rates should consider specialised messaging for average-risk females who are overweight not meeting dietary or physical activity guidelines.

Results of a fifty-gene breast cancer RNA subtype classifier applied to 167 colorectal cancer (CRC) patients.

20 Background: ERBB2 (HER2) is thought to be a target in <10% of CRC patients versus 20% of breast cancers, 15% of gastroesophageal cancers, and 10% of biliary cancers, based on FISH or IHC. Intrinsic molecular subtype is used to classify cancers into distinct biologic subtypes (eg. CMS 1-4 in CRC). A 50-gene qPCR assay (PAM50) identifies 5 intrinsic biological subtypes: luminal A, luminal B, HER2-enriched, basal-like, and normal-like in breast cancer. The HERACLES trial (trastuzumab plus lapatinib) resulted a 32% ORR and median TTP of 5.5 months in heavily pre-pretreated HER2+ CRC patients. We determined molecular subtypes using the 50-gene breast cancer classifier to identify an expanded CRC patient population eligible for HER2 therapy. Methods: Retrospective analysis on Whole exome (WES) DNA tumor and paired germline and matched deep whole transcriptomic sequencing (RNA-Seq) (∼200x106 reads per tumor) data from NantHealth was performed. Breast Cancer Intrinsic Subtypes based on RNAseq was used to classify CRC into 5 BC subtypes. Results: 167 CRC patients were classified using the Nant50 Breast Cancer classifier: 15.0% as Luminal B, 13.1% as Luminal A, and 1.8% as Basal-like. Surprisingly, 117/167 (70%) classified as HER2-enriched (HER-E). 15/167 (9.0%) had over-expression of ERBB2 by RNAseq or CN gain, which is consistent with published data of HER2+ CRC. ERBB2 is very significantly differentially expressed in HER2-E subtyped CRC (p=<0.001), more than ERBB2 CN gain, suggesting that HER2-E may be more HER2 driven. Across subtypes APC and TP53 were the most commonly mutated genes at 65.3% and 52.6% respectively, however both were more enriched in HER2-E CRC (APC OR=3.3, p=0.001, TP53 OR=2.6, p=0.007). Other known drivers of CRC such as PIK3CA, KRAS, and BRAF, were not differentially mutated in HER2-E CRC, however NRAS mutants were significantly more enriched in non-HER2-E CRC (OR=4.6, p=0.02). Conclusions: Even after excluding known HER2 over-expression and CN gain, PAM50-like gene classifier identifies a far higher than expected percentage of HER-E subtype CRC (99/167 = 59%) which may represent an under appreciated population for HER2 directed therapy and clinical trials.

CRISPR-induced RASGAP deficiencies in colorectal cancer organoids reveal that only loss of NF1 promotes resistance to EGFR inhibition.

Anti-EGFR therapy is used to treat metastatic colorectal cancer (CRC) patients, for which initial response rates of 10–20% have been achieved. Although the presence of HER2 amplifications and oncogenic mutations in KRAS, NRAS, and BRAF are associated with EGFR-targeted therapy resistance, for a large population of CRC patients the underlying mechanism of RAS-MEK-ERK hyperactivation is not clear. Loss-of-function mutations in RASGAPs are often speculated in literature to promote CRC growth as being negative regulators of RAS, but direct experimental evidence is lacking. We generated a CRISPR-mediated knock out panel of all RASGAPs in patient-derived CRC organoids and found that only loss of NF1, but no other RASGAPs e.g. RASA1, results in enhanced RAS-ERK signal amplification and improved tolerance towards limited EGF stimulation. Our data suggests that NF1-deficient CRCs are likely not responsive to anti-EGFR monotherapy and can potentially function as a biomarker for CRC progression.

Initial validation of the Danish version of the Fear of Cancer Recurrence Inventory (FCRI) in colorectal cancer patients.

The Fear of Cancer Recurrence Inventory (FCRI) is a multidimensional measure for fear of cancer recurrence (FCR). The aim of this study was to assess the psychometric properties of the translated Danish version of the FCRI in a population of colorectal cancer patients. The English version of the FCRI was forward-backward translated into Danish and pilot tested in a gynaecological cancer population. The psychometric properties of the FCRI were assessed in terms of responsiveness, test-retest reliability and discriminative and convergent validity in a population of colorectal cancer patients by asking them to complete questionnaires at three time points during follow-up. Clinical FCR was defined as ≥ 16 at the FCRI short form. The participation rate was 57%. A low association was found between higher scores on the FCRI and younger age (r = - 0.29, p = 0.02). A moderate correlation was found between the FCRI score and a measure for worry traits (r = 0.49, p < 0.001). Mean difference in total FCRI score was statistically significant between 'pre-scan' and 'postscan' (p < 0.001), thus indicating that the FCRI was responsive to change. The FCRI score showed good test-retest reliability (intraclass correlation = 0.84). The Danish version of the FCRI is a reliable and responsive measure for FCR in colorectal cancer patients and shows acceptable discriminative and convergent validity. A valid measure for FCR is crucial in order to identify patients with a need for special attention or interventions for high levels of FCR and to improve future research into FCR among cancer survivors.

The NHS Bowel cancer screening programme achieves the anticipated survival improvement, but participation must be improved

PurposeThe NHS Bowel cancer screening programme (NHSBCSP) aims to reduce colorectal cancer (CRC) cumulative mortality by up to 23 per cent; long-term outcomes at national level are not yet known. The purpose of this paper is to examine a local population of CRC patients of screening age for their characteristics and long-term survival in relation to their presentation, including through the NHSBCSP.Design/methodology/approachRetrospective analysis of a prospectively maintained CRC database for the years 2009-2014 in a single district hospital providing bowel cancer screening and tertiary rectal cancer services.FindingsOf 528 CRC patients diagnosed in the screening age range, 144(27.3 per cent) presented through NHSBCSP, 308(58.3 per cent) electively with symptoms and 76(14.4 per cent) as emergency. NHSBCSP-diagnosed patients were younger (median 66 vs 68 and 69 years, respectively, p=0.001), had more often left-sided cancers (59(41.0 per cent) vs 82(26.6 per cent) and 24(31.6 per cent), respectively, p=0.001), more UICC-stage I (42(29.2 per cent) vs 49(15.9 per cent) and 2(2.6 per cent)), stage III (59(41.0 per cent) vs 106(34.4 per cent) and 20(26.3 per cent)) and less stage IV disease (8(5.6 per cent) vs 61(19.8 per cent) and 34 (44.7 per cent), respectively, p<0.001). Three-year overall survival was best for NHSBCSP and worst for emergency patients (87.5 per cent vs 69.0 per cent and 35.3 per cent, respectively, LogRank p<0.001).Originality/valuePatients diagnosed within the NHSBCSP have improved outcome compared to both symptomatic elective and emergency presentations. A reduction in overall cumulative mortality in order of 25 per cent may well be achieved, but continuing high levels of emergency presentations and undetected right-sided disease emphasise need for further improvement in public participation in the NHSBCSP and research into more sensitive and acceptable alternative screening methods.

The association between microsatellite instability and lymph node count in colorectal cancer.

The number of lymph nodes retrieved from colorectal cancer (CRC) resection specimens is crucial for adequate diagnosis and therapy. Previous studies indicate that in addition to the extent of surgical resection and the quality of pathological lymph node examination, non-modifiable tumour parameters like microsatellite instability (MSI) are associated with higher lymph node count. In order to study the potential influence of MSI on lymph node count, we analysed a previously MSI-typed population of CRC patients (n=1196) to determine the relationship between MSI and the frequency with which at least 12 lymph nodes were retrieved, as well as the mean and median number of retrieved lymph nodes. MSI was associated with an increased frequency of 12-node retrieval, as well as a higher mean and median lymph node count in the overall analysis (p 0.004 and 0.001 for 12-node retrieval and lymph node count, respectively). However, when the analysis was restricted to cancers of the proximal colon, the main location of microsatellite unstable tumours (84% in our study), no association between MSI and 12-node retrieval was found. Subcategorisation by UICC stage of proximally located cancers showed a statistically significant increase in the lymph node count only in microsatellite unstable stage I tumours (p 0.010). In conclusion, our data shows that previously reported associations between MSI and higher lymph node count are mainly a consequence of the increased incidence of microsatellite unstable cancer in the proximal colon. Our finding that MSI is related to a significantly higher mean lymph node count in proximal stage I cancers may indicate that the immunogenicity of this molecular tumour type induces earlier lymph node activation.

535P - Concordance of KRAS, NRAS and BRAF status between primary colorectal tumors and paired metastasis (mts)

It is well established that patients with RAS-mutant colorectal cancer (CRC) are resistant to anti-EGFR therapies and it is suggested that BRAF mutations may also have a predictive value. However, it is not known which is the most suitable specimen for mutation testing. Although it has been postulated a high concordance of KRAS status between primary tumors (pt) and liver mts, there are contradictory results. In this study we investigated the concordance of KRAS, NRAS and BRAF between pt and matched hepatic and extrahepatic mts. We examined 31 pairs of pt and mts (liver, lung, peritoneum, lymph nodes,ovary and pleura samples) of patients with CRC treated at Costa del Sol Hospital. DNA was extracted from formalin-fixed, paraffin-embedded specimens, using the DNA Tissue Kit (Qiagen). After verifying the quality of DNA, CLART CMA KRAS-BRAF Kit and Therascreen Kit or Therascreen KRAS RGQ PCR Kit, exon 15 BRAF sequencing and Therascreen Pyro Kit were employed to detect mutations in KRAS, NRAS and BRAF. To evaluate concordance differences, we used Fisher Test for independent cualitative variables, and U Mann-Whitney Test for cuantitative variables. Concordance rate of KRAS, NRAS and BRAF mutational status between pt and mts of any location was 79.1% (95% Confidence Interval: CI 65.7-92.4).Tabled 1Pt-Liver mtsPt- Extrahepatic mtsPt-Any location mtsKRAS78.9% (15/19)72.7% (8/11)76.7% (95% CI 59.9-93.5)NRAS66.7% (4/6)71.4% (5/7)71.4% (95% CI 29.0-96.3)BRAF100% (5/5)100% (1/1)100% (95% CI 54.1-100) Open table in a new tab We found that discordant pairs of pt-liver mts for KRAS showed more frequently a percentage of tumor cells in pt samples <70% (60% of cases versus 40% for concordant cases; p 0.044). Moreover, a trend for higher concordance of KRAS was showed for colon compared to rectal primaries (86.7% versus 50%; p 0.178). Concordance rate of approximately 80% can be found between pt and corresponding mts in unselected population of CRC patients. Percentage of tumor cells in samples can affect results. More studies are needed to clarify causes for discordance in mutational status of different samples from the same patient.

Promoter methylation of ITF2, but not APC, is associated with microsatellite instability in two populations of colorectal cancer patients.

BackgroundAberrant Wnt signaling activation occurs commonly in colorectal carcinogenesis, leading to upregulation of many target genes. APC (adenomatous polyposis coli) is an important component of the β-catenin destruction complex, which regulates Wnt signaling, and is often mutated in colorectal cancer (CRC). In addition to mutational events, epigenetic changes arise frequently in CRC, specifically, promoter hypermethylation which silences tumor suppressor genes. APC and the Wnt signaling target gene ITF2 (immunoglobulin transcription factor 2) incur hypermethylation in various cancers, however, methylation-dependent regulation of these genes in CRC has not been studied in large, well-characterized patient cohorts. The microsatellite instability (MSI) subtype of CRC, featuring DNA mismatch repair deficiency and often promoter hypermethylation of MutL homolog 1 (MLH1), has a favorable outcome and is characterized by different chemotherapeutic responses than microsatellite stable (MSS) tumors. Other epigenetic events distinguishing these subtypes have not yet been fully elucidated.MethodsHere, we quantify promoter methylation of ITF2 and APC by MethyLight in two case-case studies nested in population-based CRC cohorts from the Ontario Familial Colorectal Cancer Registry (n = 330) and the Newfoundland Familial Colorectal Cancer Registry (n = 102) comparing MSI status groups.ResultsITF2 and APC methylation are significantly associated with tumor versus normal state (both P < 1.0×10-6). ITF2 is methylated in 45.8 % of MSI cases and 26.9 % of MSS cases and is significantly associated with MSI in Ontario (P = 0.002) and Newfoundland (P = 0.005) as well as the MSI-associated feature of MLH1 promoter hypermethylation (P = 6.72×10-4). APC methylation, although tumor-specific, does not show a significant association with tumor subtype, age, gender, or stage, indicating it is a general tumor-specific CRC biomarker.ConclusionsThis study demonstrates, for the first time, MSI-associated ITF2 methylation, and further reveals the subtype-specific epigenetic events modulating Wnt signaling in CRC.

Guidelines-based diagnostic process does increase hospital delay in a cohort of colorectal cancer patients: a population-based study.

This is an investigation of factors determining hospital delay until treatment in an unrestricted population of colorectal cancer patients in the western part of the Netherlands. All patients with newly diagnosed colon (n=2146) and rectal carcinoma (n=1036) in the period 2006-2008 were included in analyses of inhospital delay (first hospital visit until first treatment >35 days). One-third of all patients were also available for analyses of prehospital delay (enrollment until first hospital visit >7 days). Patient, tumour and process factors predicting delay were examined in logistic regression models. The median prehospital and inhospital time intervals were 2 days [(p25-p75) 0-16] and 32 days (17-49), respectively, for colon cancer patients and 7 days (1-21) and 43 days (33-60) for rectal cancer patients. After adjustment for patient and tumour factors, colon and rectal cancer patients with first hospital visit before histological confirmation of cancer, complete diagnostic assessment or discussed in a multidisciplinary meeting had a higher probability of increased inhospital delay. Furthermore, first hospital visit before histological confirmation of cancer was associated with decreased prehospital delay in colon and rectal cancer patients. A guidelines-based diagnostic process (considered high quality of care) and multidisciplinary collaboration were associated with increased hospital delay in colorectal cancer patients.

Comparison of KRAS mutation analysis of colorectal cancer samples by standard testing and next-generation sequencing

AimsBased on KRAS testing, the subset of patients with metastatic colorectal cancer (CRC) that could benefit from anti-EGFR therapy can be better delineated. Though KRAS testing has become significantly more...

CYP2W1 Polymorphism: Functional Aspects and Relation to Risk for Colorectal Cancer

This study aims to investigate the possible association between the risk of colorectal cancer (CRC) and allelic variants of CYP2W1 and their functional properties. The distribution of three different CYP2W1 alleles (CYP2W1*1, CYP2W1*2 and CYP2W1*6) in 1785 CRC patients and 1761 healthy blood donors was determined using the TaqMan(®) (Applied Biosystems, CA, USA) allelic discrimination assay or allele-specific amplification. Corresponding gene products (CYP2W1.1, CYP2W1.2 and CYP2W1.6) were expressed in human colon cancer SW480 cells and their activities towards two different substrates, the duocarmycin analogs ICT2706 and ICT2726, were monitored. No significant differences in the distribution of CYP2W1*1, CYP2W1*2 and CYP2W1*6 alleles were found between CRC patients and controls. The CYP2W1.1, CYP2W1.2 and CYP2W1.6 variant enzymes were expressed at the similar levels in the transfected SW480 cells and had comparable kinetics in terms of the metabolism of the duocarmycin ICT2726, as well as in the bioactivation of ICT2706 into a cytotoxic product. These epidemiological data obtained from a large population of CRC patients and controls cannot confirm the previously suggested decreased risk for CRC among carriers of CYP2W1*2. On the molecular level, this conclusion is further supported by the similar catalytic characteristics of the CYP2W1.1, CYP2W1.2 and CYP2W1.6 variants of CYP2W1.

Germline mutation and protein expression analysis of mismatch repair genes MSH6 and PMS2 in Malaysian Lynch syndrome patients

Dear Editor: Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is the most common hereditary form of colorectal cancer (CRC). The diagnosis of HNPCC or Lynch syndrome represents a major challenge because of its genotype and phenotype heterogeneity. Although Amsterdam criteria and Bethesda criteria might be useful for the diagnosis assessment of HNPCC family, there will be clinical situations involving families that may be wholly uninformative for the application of these criteria. The genetic basis of Lynch syndrome has been associated with potentially pathogenic mutations in a group of DNA MMR genes (MLH1 , MSH2 , MSH6 , PMS1 , and PMS2). Germline mutation analysis of DNA MMR genes is the most crucial process for the confirmation of the clinical diagnosis of Lynch syndrome cases. The mutation spectrum of DNA MMR genes appear to be diverse in both distribution and nature of mutations. Although mutation data is available from different parts of the world in varying frequencies, reports on Malaysian patients are scarce. This study was undertaken to unravel the spectrum of germline mutation in DNA MMR genes in Malaysian Lynch syndrome patients. Due to the minor role of germline MSH6 and PMS2 mutations, we adapted the Lynch syndrome detection strategy for the Malaysian population of CRC patients, whereby germline mutations were first sought for MLH1 and MSH2 genes, to be followed byMSH6 and PMS2 genes. The choice about which gene should be tested first was guided by immunohistochemical (IHC) analysis of protein expression of MMR genes. Earlier, we did germlinemutation analysis ofMLH1 and MSH2 genes in 50 Lynch syndrome patients, out of which the data for 34 Lynch syndrome patients has already been reported [1]. In addition to and continuation of the previous report, this report specifically focus on the protein expression profile and germline mutations of MSH6 and PMS2 genes in 50 Malaysian Lynch syndrome suspected patients.

S100A10 as a novel biomarker in colorectal cancer

Recent data support the role of S100A10 in tumorigenesis. In this study, we evaluated the value of S100A10 positivity as a possible biomarker in colorectal cancer. We evaluated S100A10 positivity by immunohistochemistry in a large population of colorectal cancer patients (n = 882). The relationships between S100A10 positivity and clinicopathological features and clinical outcome were analyzed. There were 36 % (319/882) tumors positive for S100A10 in all colorectal cancer samples. In contrast, normal colorectal epithelium was negative for S100A10 among all 562 specimens of adjacent normal mucosa. S100A10 positivity was correlated with poor differentiation (p = 0.0012) and disease stage (p = 0.003). S100A10 positivity was significantly correlated with shortened specific [log-rank p < 0.001; multivariate hazard ratio (HR), 1.49; 95% confidence interval (CI), 1.09-2.04] and overall survival (log-rank p = 0.0012; multivariate HR, 1.34; 95% CI, 1.06-1.73). Knockdown of S100A10 by siRNA significantly reduced the proliferation, migration, and invasion capacity of colorectal cancer cell lines. Our results suggest a role for S100A10 as a prognostic marker and potential therapeutic target in colorectal cancer.

Overexpression of epidermal growth factor receptor as a prognostic factor in colorectal cancer on the basis of the Allred scoring system

BackgroundOverexpression of epidermal growth factor receptor (EGFR) is found in many types of neoplasms. The aim of the study was to evaluate EGFR expression in colorectal cancer (CRC) specimens and to determine whether EGFR expression correlates with clinicopathological data and overall survival.Patients and methodsTissue specimens from 181 consecutive CRC patients treated at the Military Institute of Medicine in 2006–2010 were collected and examined for EGFR expression, by immunohistochemistry staining. The staining intensity and percentage of cells with membranous EGFR expression were scored and then grouped according to the parameters of the Allred Scoring system. Cutoff values were subjected to further statistical analysis. Univariate tests and a multivariate Cox proportional hazards model were used in data analysis.ResultsEGFR was overexpressed in 96 of 181 CRC specimens (53%). EGFR expression was not correlated with other clinicopathological variables. On univariate analysis, overexpression of EGFR, determined by PS (percentage score) (>3) and total score (sum of PS and intensity score) (>4), was associated with poor overall survival. On multivariate analysis, EGFR overexpression (PS > 3) was an independent adverse prognostic factor (hazard ratio [HR] 1.62; 95% confidence interval [CI]: 1.03–2.53). Elevated carcinoembryonic antigen (CEA) serum concentration before treatment, performance status (Word Health Organization [WHO]-2), and tumor localized in colon and liver metastases were also independent unfavorable prognostic factors.ConclusionEGFR overexpression (PS > 3) in a CRC patient population was an independent adverse prognostic factor. Implementation of the Allred Scoring system criteria into clinical practice might facilitate treatment decisions in CRC patients.

Diabetes, metformin use, and colorectal cancer survival in postmenopausal women

Background: Observational studies have associated metformin use with lower colorectal cancer (CRC) incidence but few studies have examined metformin's influence on CRC survival. We examined the relationships among metformin use, diabetes, and survival in postmenopausal women with CRC in the Women's Health Initiative (WHI) clinical trials and observational study. Methods: 2066 postmenopausal women with CRC were followed for a median of 4.1 years, with 589 deaths after CRC diagnosis from all causes and 414 deaths directly attributed to CRC. CRC-specific survival was compared among women with diabetes with metformin use (n=84); women with diabetes with no metformin use (n=128); and women without diabetes (n=1854). Cox proportional hazard models were used to estimate associations among metformin use, diabetes and survival after CRC. Strategies to adjust for potential confounders included: multivariate adjustment with known predictors of colorectal cancer survival and construction of a propensity score for the likelihood of receiving metformin, with model stratification by propensity score quintile. Results: After adjusting for age and stage, CRC specific survival in women with diabetes with metformin use was not significantly different compared to that in women with diabetes with no metformin use (HR 0.75; 95% CI 0.40–1.38, p=0.67) and to women without diabetes (HR 1.00; 95% CI 0.61–1.66, p=0.99). Following propensity score adjustment, the HR for CRC-specific survival in women with diabetes with metformin use compared to non-users was 0.78 (95% CI 0.38–1.55, p=0.47) and for overall survival was 0.86 (95% CI 0.49–1.52; p=0.60). Conclusions: In postmenopausal women with CRC and DM, no statistically significant difference was seen in CRC specific survival in those who used metformin compared to non-users. Analyses in larger populations of colorectal cancer patients are warranted.

The relationship between visceral obesity and colorectal cancer

SUMMARY The prevalence of obesity continues to rise globally and physicians and healthcare systems have to prepare for rising rates of obesity-associated disease. Aside from cardiovascular disease and diabetes, recent evidence suggests a strong association between obesity and the development of cancer, including colorectal cancer. Using BMI as a marker for obesity, excess body fat is associated with an increased risk of colorectal cancer; however, this relationship appears to be stronger among males and more consistent for colon rather than rectal cancer. Epidemiologic literature evaluating the risk of obesity on colorectal cancer survival using BMI is less consistent. Recent evidence suggests that visceral fat plays a greater role in the development of disease. Current research on the effect of visceral obesity on colorectal cancer outcomes is in its infancy, but may drive a new wave of practice for this ever-growing population of colorectal cancer patients.

Abstract 1912: An explorative analysis of ERCC1/ERCC4 copy number alterations in a chemonaive stage III colorectal cancer patient cohort.

Abstract Background: Platinum-based chemotherapy is widely used in the treatment of cancer. Oxaliplatin, used in combination with 5-Fluorouracil in colorectal cancer (CRC), induces DNA damage which leads to death of the cancer cell. Oxaliplatin DNA damage can be removed by the nucleotide excision repair system. Two components of this system, ERCC1 and ERCC4, have previously been implicated in sensitivity/resistance to platinum-based treatment. The present study explores the mechanism, frequency and prognostic impact of ERCC1 and ERCC4 gene alterations in advanced CRC. Methods: Fluorescent In Situ Hybridization (FISH) probes directed at ERCC1 (location: 19q13.32) and ERCC4 (location: 16p13.12) were constructed. Nine CRC cell line metaphase spreads were analyzed with an ERCC1 probe in combination with a reference probe covering the centromeric region of chromosome 2 (CEN-2) and with an ERCC4 probe combined with CEN-16. FFPE tissue sections from 152 stage III CRC (81 colon, 71 rectum) chemonaive patients were analyzed. Relationships between biomarker status and overall survival (OS) and time to recurrence (TTR) were analyzed using multivariate statistics. Results: ERCC1 alterations were observed in a single cell line metaphase (HT29), whereas no alterations were observed with ERCC4. Among the 152 patient tumor sections which were successfully analyzed with ERCC1/CEN-2, 43 (28.3%) patients harbored an ERCC1 aberration, specifically: 2 (1.3%) deletions (ERCC1/CEN-2 &amp;lt; 0.8) and 41 (27.0%) gains (ERCC1/CEN-2 ≥ 1.5). ERCC1 gains were detected in 17 (21.0%) and 24 (33.8%) colon and rectum tumor specimens, respectively; whereas ERCC1 deletions were only detected in colonic tumors. Increased ERCC1 gene copy numbers, when analyzed as a continuous variable, were significantly associated with longer survival (HR: 0.32, 95% CI: 0.14-0.75, p=0.01) and TTR (HR: 0.34, 95% CI: 0.12-1.00, p=0.0498) in tumors of the colon, but not with rectal tumors (OS HR: 1.01, p=0.66; TTR HR: 0.87, p=0.77). Similarly, ERCC1 gains (ERCC1/CEN-2 ≥ 1.5) showed a trend towards longer OS (HR: 0.46, 95% CI: 0.20-1.02, p=0.06) and TTR (HR: 0.44, 95% CI: 0.17-1.14, p=0.09) for patients with tumors of colonic origin, but not for those with rectal tumors. The impact of ERCC1 deletions were not analyzed due to the low number of patients, and were excluded from survival analysis. No ERCC4 aberrations were detected and scoring was discontinued after 50 patients. Conclusions: ERCC1 gene gain occurs frequently in stage III CRC, whereas ERCC1 loss occurs infrequently. Higher ERCC1 counts and ERCC1/CEN-2 ratios were significantly associated longer OS and TTR in patients with colonic tumors. Accordingly, ERCC1 gain (ERCC1/CEN-2 ≥ 1.5) showed a similar tendency towards longer OS and TTR for colonic tumors. Future studies will investigate the effect of ERCC1 aberrations in a platinum-treated CRC patient population. Citation Format: David H. Smith, Niels F. Jensen, Ib J. Christensen, Sven Müller, Hans J. Nielsen, Nils Brünner, Kirsten V. Nielsen. An explorative analysis of ERCC1/ERCC4 copy number alterations in a chemonaive stage III colorectal cancer patient cohort. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1912. doi:10.1158/1538-7445.AM2013-1912

PCN64 The Cost Effectiveness of Cetuximab Plus Best Supportive Care (BSC) Versus BSC Alone in Last Line for KRAS Wild Type Metastatic Colorectal Cancer Patient Population

PCN64 The Cost Effectiveness of Cetuximab Plus Best Supportive Care (BSC) Versus BSC Alone in Last Line for KRAS Wild Type Metastatic Colorectal Cancer Patient Population

Diabetes, metformin use, and colorectal cancer survival in women: A retrospective cohort study.

e14005 Background: Observational studies have associated metformin use with lower colorectal cancer incidence but few studies have examined survival impact. We examined the relationship between metformin use, diabetes, and survival in postmenopausal women diagnosed with colorectal cancer while participating in the Women’s Health Initiative (WHI) Clinical Trial or Observational Study. Methods: 2,066 postmenopausal women with colorectal cancer diagnosed while enrolled in the WHI were followed for a median of 4.1 years, with 589 deaths overall and 414 colorectal cancer deaths. In this cohort, overall and colorectal cancer-specific survival were compared among women with diabetes who reported ever using metformin (n=84); those with no reported use of metformin (n=128); and women without diabetes (n=1854). Cox proportional hazard models were used to estimate the associations between metformin use, diabetes and survival outcomes from the time of colorectal cancer diagnosis. Two strategies were used to adjust for potential confounders: multivariate adjustment with known predictors of colorectal cancer survival and construction of a propensity score for the likelihood of receiving metformin, with model stratification by propensity score quintile. Results: After adjusting for age and stage at diagnosis, women with diabetes on metformin had no significant difference in colorectal-cancer specific survival compared to metformin non-users (HR 0.75; 95% CI 0.40 -1.38, p=0.67) or compared to women without diabetes (HR 1.00; 95% CI 0.61 - 1.66, p=0.99). With propensity score adjustment, the HR for colorectal cancer-specific survival in women with diabetes on metformin compared to non-users was 0.90 (95% CI 0.48 – 1.69, p=0.75). Women with diabetes reporting metformin use had no significant difference in overall survival compared to non-users (HR 0.84; 95% CI 0.51 – 1.37; p=0.48) or non-diabetics (HR 1.20; 95% CI 0.80 - 1.79; p=0.39). Conclusions: In postmenopausal women with colorectal cancer and diabetes, no statistically significant difference was seen in colon-cancer specific survival in those who used metformin. Analyses in larger populations of colorectal cancer patients are warranted.

Aberrant protein expression and frequent allelic loss of MSH3 in colorectal cancer with low-level microsatellite instability

High level of microsatellite instability (MSI-H) in colorectal cancer (CRC) is caused by the inactivation of mismatch repair (MMR) genes; however, it is unknown for tumors with low level MSI (MSI-L). The protein complex involving MSH3 preferentially recognizes insertion/deletion loops (IDLs) of two to eight bases and di- and tetranucleotide repeats are affected in the majority of MSI-L CRC. We selected 10 and eight MSI-L CRCs from 228 and 204 patients with sporadic and hereditary disease, respectively. The tumors were analyzed for protein expression of MSH3, MSH2, MSH6, MLH1, and PMS2, and for mutations and loss of heterozygosity (LOH) in MSH3. Four tumors showed a markedly reduced MSH3 expression, whereas all 18 tumors had normal expression of the remaining MMR proteins. Twenty-five different sequence variants were identified. None of these results in a truncated protein, though L902W represents the first constitutional missense mutation in MSH3 predicted to be functional based on conservation among mutS homologues. All variants have also been found in normal DNA of the patients and in controls. LOH intragenic to MSH3 was evident for 12 of 16 (75%) informative tumors. Occurrence of sequence variants in normal DNA of the patients and in controls excludes somatic mutations and mutations specific to the CRC patient population, respectively. In contrast, the high frequency of LOH as well as the aberrant protein expression in some tumors indicates an involvement of MSH3 impairment in MSI-L CRC.