Steven Gallinger

Meta-analysis of genome-wide association data identifies four new susceptibility loci for colorectal cancer

Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly influence the risk of developing colorectal cancer (CRC). To enhance power to identify additional loci with similar effect sizes, we conducted a meta-analysis of two GWA studies, comprising 13,315 individuals genotyped for 38,710 common tagging SNPs. We undertook replication testing in up to eight independent case-control series comprising 27,418 subjects. We identified four previously unreported CRC risk loci at 14q22.2 (rs4444235, BMP4; P = 8.1 × 10−10), 16q22.1 (rs9929218, CDH1; P = 1.2 × 10−8), 19q13.1 (rs10411210, RHPN2; P = 4.6 × 10−9) and 20p12.3 (rs961253; P = 2.0 × 10−10). These findings underscore the value of large sample series for discovery and follow-up of genetic variants contributing to the etiology of CRC.

EphB receptor activity suppresses colorectal cancer progression

Most sporadic colorectal cancers are initiated by activating Wnt pathway mutations, characterized by the stabilization of β-catenin and constitutive transcription by the β-catenin/T cell factor-4 (Tcf-4) complex. EphB guidance receptors are Tcf4 target genes that control intestinal epithelial architecture through repulsive interactions with Ephrin-B ligands. Here we show that, although Wnt signalling remains constitutively active, most human colorectal cancers lose expression of EphB at the adenoma–carcinoma transition. Loss of EphB expression strongly correlates with degree of malignancy. Furthermore, reduction of EphB activity accelerates tumorigenesis in the colon and rectum of ApcMin/+ mice, and results in the formation of aggressive adenocarcinomas. Our data demonstrate that loss of EphB expression represents a critical step in colorectal cancer progression.

Survival after hepatic resection for colorectal metastases: a 10-year experience.

BackgroundMetastatic colorectal cancer is a major cause of cancer death in North America. Hepatic resection offers the potential for cure in selected patients. We report the long-term outcomes of patients who underwent hepatic resection for colorectal metastases over a 10-year period at a single hepatobiliary surgical oncology center.MethodsAll patients who underwent liver resection for metastatic colorectal cancer between 1992 and 2002 were identified. Data were retrospectively obtained through chart review. Major outcome variables were disease-free survival and overall survival. Risk factors for disease recurrence and mortality were identified by multivariate analysis by using the Cox proportional hazard method.ResultsA total of 423 hepatectomies were performed for metastatic colorectal cancer. Most operations (n = 276; 65%) were major (four or more segments) hepatectomies. Perioperative morbidity occurred in 74 (17%) patients. There were seven (1.6%) perioperative deaths. The disease-free survival at 1, 5, and 10 years was 64%, 27%, and 22%, respectively. The overall survival at 1, 5, and 10 years was 93%, 47%, and 28%, respectively. Multivariate analysis identified four negative predictive factors for overall survival (hazard ratio; 95% confidence interval): a positive surgical margin (2.9; 1.5–5.3), large metastases (>5 cm; 1.5; 1.1–2.0), multiple metastases (1.4; 1.1–1.9), and age >60 years (1.4; 1.1–1.9).ConclusionsHepatic resection for metastatic colorectal cancer is safe and provides good long-term overall survival rates of 47% at 5 years and 28% at 10 years. An aggressive approach is justified by the low operative mortality rate and good long-term survival, even in individuals with multiple bilobar metastases.Metastatic colorectal cancer is a major cause of cancer death in North America. Hepatic resection offers the potential for cure in selected patients. We report the long-term outcomes of patients who underwent hepatic resection for colorectal metastases over a 10-year period at a single hepatobiliary surgical oncology center. All patients who underwent liver resection for metastatic colorectal cancer between 1992 and 2002 were identified. Data were retrospectively obtained through chart review. Major outcome variables were disease-free survival and overall survival. Risk factors for disease recurrence and mortality were identified by multivariate analysis by using the Cox proportional hazard method. A total of 423 hepatectomies were performed for metastatic colorectal cancer. Most operations (n = 276; 65%) were major (four or more segments) hepatectomies. Perioperative morbidity occurred in 74 (17%) patients. There were seven (1.6%) perioperative deaths. The disease-free survival at 1, 5, and 10 years was 64%, 27%, and 22%, respectively. The overall survival at 1, 5, and 10 years was 93%, 47%, and 28%, respectively. Multivariate analysis identified four negative predictive factors for overall survival (hazard ratio; 95% confidence interval): a positive surgical margin (2.9; 1.5–5.3), large metastases (>5 cm; 1.5; 1.1–2.0), multiple metastases (1.4; 1.1–1.9), and age >60 years (1.4; 1.1–1.9). Hepatic resection for metastatic colorectal cancer is safe and provides good long-term overall survival rates of 47% at 5 years and 28% at 10 years. An aggressive approach is justified by the low operative mortality rate and good long-term survival, even in individuals with multiple bilobar metastases.

Colorectal and Other Cancer Risks for Carriers and Noncarriers From Families With a DNA Mismatch Repair Gene Mutation: A Prospective Cohort Study

PURPOSE To determine whether cancer risks for carriers and noncarriers from families with a mismatch repair (MMR) gene mutation are increased above the risks of the general population. PATIENTS AND METHODS We prospectively followed a cohort of 446 unaffected carriers of an MMR gene mutation (MLH1, n = 161; MSH2, n = 222; MSH6, n = 47; and PMS2, n = 16) and 1,029 their unaffected relatives who did not carry a mutation every 5 years at recruitment centers of the Colon Cancer Family Registry. For comparison of cancer risk with the general population, we estimated country-, age-, and sex-specific standardized incidence ratios (SIRs) of cancer for carriers and noncarriers. RESULTS Over a median follow-up of 5 years, mutation carriers had an increased risk of colorectal cancer (CRC; SIR, 20.48; 95% CI, 11.71 to 33.27; P < .001), endometrial cancer (SIR, 30.62; 95% CI, 11.24 to 66.64; P < .001), ovarian cancer (SIR, 18.81; 95% CI, 3.88 to 54.95; P < .001), renal cancer (SIR, 11.22; 95% CI, 2.31 to 32.79; P < .001), pancreatic cancer (SIR, 10.68; 95% CI, 2.68 to 47.70; P = .001), gastric cancer (SIR, 9.78; 95% CI, 1.18 to 35.30; P = .009), urinary bladder cancer (SIR, 9.51; 95% CI, 1.15 to 34.37; P = .009), and female breast cancer (SIR, 3.95; 95% CI, 1.59 to 8.13; P = .001). We found no evidence of their noncarrier relatives having an increased risk of any cancer, including CRC (SIR, 1.02; 95% CI, 0.33 to 2.39; P = .97). CONCLUSION We confirmed that carriers of an MMR gene mutation were at increased risk of a wide variety of cancers, including some cancers not previously recognized as being a result of MMR mutations, and found no evidence of an increased risk of cancer for their noncarrier relatives.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge–purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10−7) in SOX2OT and rs17030795 (P=5.84 × 10−6) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10−6) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10−6) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10−6), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Case–Control Study of Overweight, Obesity, and Colorectal Cancer Risk, Overall and by Tumor Microsatellite Instability Status

BACKGROUND Being overweight or obese is an established risk factor for colorectal cancer, more so for men than for women. Approximately 10%-20% of colorectal tumors display microsatellite instability (MSI), defined as the expansion or contraction of small repeated sequences in the DNA of tumor tissue relative to nearby normal tissue. We evaluated associations between overweight or obesity and colorectal cancer risk, overall and by tumor MSI status. METHODS The study included 1794 case subjects with incident colorectal cancer who were identified through population-based cancer registries and 2684 of their unaffected sex-matched siblings as control subjects. Recent body mass index (BMI), BMI at age 20 years, and adult weight change were derived from self-reports of height and weight. Tumor MSI status, assessed at as many as 10 markers, was obtained for 69.7% of the case subjects and classified as microsatellite (MS)-stable (0% of markers unstable; n = 913), MSI-low (>0% but <30% of markers unstable; n = 149), or MSI-high (> or =30% of markers unstable; n = 188). Multivariable conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). All statistical tests were two-sided. RESULTS Recent BMI, modeled in 5 kg/m(2) increments, was positively associated with risk of colorectal cancer for men and women combined (OR = 1.24; 95% CI = 1.15 to 1.34), for women only (OR = 1.20; 95% CI = 1.10 to 1.32), and for men only (OR = 1.30; 95% CI = 1.15 to 1.47). There was no interaction with sex (P = .22). Recent BMI, per 5 kg/m(2), was positively associated with the risk of MS-stable (OR = 1.38; 95% CI = 1.24 to 1.54) and MSI-low (OR = 1.33; 95% CI = 1.04 to 1.72) colorectal tumors, but not with the risk of MSI-high tumors (OR = 1.05; 95% CI = 0.84 to 1.31). CONCLUSION The increased risk of colorectal cancer associated with a high BMI might be largely restricted to tumors that display the more common MS-stable phenotype, suggesting further that colorectal cancer etiology differs by tumor MSI status.

Variants on 9p24 and 8q24 Are Associated with Risk of Colorectal Cancer: Results from the Colon Cancer Family Registry

Recent publications have reported that common variants on 8q24 are associated with both prostate and colorectal cancers (CRC). In addition, one of these studies (the ARCTIC study) initially observed an association with a single nucleotide polymorphism (SNP) on 9p24 that was not confirmed in some of their validation data sets. In the research described here, we conducted a case-unaffected sibling analysis using population- and clinic-based discordant sibships (N = 1,567 sibships) from the Colon Cancer Family Registry (Colon CFR) to investigate the associations between common variants at 9p24 and 8q24 and risk of CRC. We also evaluated whether these associations differed by age, family history, and tumor characteristics, including microsatellite instability and tumor site. Associations were estimated using conditional logistic regression, treating sibship as the matching factor. Analyses were adjusted for age and sex, and stratified by ascertainment source (population versus clinic). We observed an association between a SNP on 9p24 (rs719725) and risk of CRC in the population-based series (AA versus CC: odds ratios, 1.46; 95% confidence interval, 1.06-2.02; AC versus CC: odds ratios, 1.50; 95% confidence interval, 1.14-1.98; P = 0.011 on 2 df). In the population-based series, we also detected statistically significant associations between two SNPs on 8q24, rs10505477 and rs6983267, and risk of CRC (P = 0.005 and P = 0.002, respectively). There was no evidence of statistically significant heterogeneity by age at diagnosis, family history of CRC, microsatellite instability, or tumor site at either locus and no evidence of interaction between SNPs on 8q24 and 9p24. These data suggest that common variants may play important roles in the risk of CRC.

Relatives of colorectal cancer patients: Factors associated with screening behavior

BACKGROUND The purpose of this study was to identify whether decisions regarding colorectal cancer (CRC) screening by relatives of CRC patients are influenced by social interactions with family members, friends, and physicians or by public awareness campaigns. METHODS Screened (n=236) and nonscreened (n=132) relatives of CRC patients were interviewed in 2001. A socioecologic model was used as the framework for the interview variables, which included interactions with relatives, medical professionals, and social groups, as well as perceived benefits and barriers to screening and perceived susceptibility. RESULTS Physician encouragement, fewer barriers to screening, strong CRC family history, encouragement from relatives, advice from a surgeon, and discussion of CRC screening with social groups were all associated with ever having been screened. Having been encouraged by a physician was the strongest correlate of screening behavior. Perceived susceptibility to CRC, advice from family members, and exposure to public awareness information were not associated with screening. CONCLUSIONS The socioecologic framework is a good explanatory model of CRC screening in increased-risk relatives, as variables from each level were associated with screening. These findings can guide interventions aimed at increasing screening uptake, particularly those involving physicians.

Familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is a dominantly inherited familial cancer syndrome characterized by an increased predisposition to colorectal cancer and other benign and malignant extra-colonic lesions. FAP has been linked to germline mutations of the adenomatous polyposis coli (APC) gene that encodes a protein with 2,843 amino acids that has important functions in the regulation of cell growth. A genotype-phenotype correlation has also been observed between mutations in the APC gene and polyp phenotype. We review the clinical and genetic features of this disorder and provide information on the diagnostic approaches and treatment options available for this disease.

High Frequency of Hereditary Colorectal Cancer in Newfoundland Likely Involves Novel Susceptibility Genes

Purpose: Newfoundland has one of the highest rates of colorectal cancer in North America. The most common hereditary form of colorectal cancer is hereditary nonpolyposis colorectal cancer caused by mutations in genes involved in mismatch repair. Our purpose was to determine the proportion of hereditary colorectal cancer and to determine the genetic basis of disease in both population and clinically referred cohorts from Newfoundland. Experimental Design: Seventy-eight colorectal cancer patients were accrued over a 2-year period from the Avalon Peninsula of Newfoundland. We also examined 31 hereditary nonpolyposis colorectal cancer–like families, which had been referred to the Provincial Medical Genetics Program. Tumors from probands were tested by immunohistochemistry for deficiencies in MLH1, MSH2, and MSH6 proteins and tested for DNA microsatellite instability. Mutation analyses of MLH1, MSH2, and MSH6 were undertaken by direct sequencing and an assay to detect deletions, amplifications, and rearrangements in MSH2 and MLH1. Results: We identified eight population-based families that fulfill the Amsterdam I or II criteria, 4 (50%) of which seem to have hereditary cancer not attributable to the most commonly mutated mismatch repair genes. In addition, in 16 of 21 (76%) referred families fulfilling Amsterdam I or II criteria, no mutations were found in the three most commonly altered mismatch repair genes, and tumor analyses corroborated these findings. Conclusions: It seems that strong and novel genetic causes of hereditary colorectal cancer are responsible for a high proportion of colorectal cancer in this population. Conditions are suitable for the identification of these genes by linkage studies of large Newfoundland cancer families.