Syndromic colon cancer: lynch syndrome and familial adenomatous polyposis

Inulin as a Delivery Vehicle for Targeting Colon-Specific Cancer

Natural polysaccharides, as well as biopolymers, are now days widely developed for targeting colon cancer using various drug delivery systems. Currently, healing conformations are being explored that can efficiently play a multipurpose role. Owing to the capability of extravagance colonic diseases with the least adverse effects, biopolymers for site specific colon delivery have developed an increased curiosity over the past decades. Inulin (INU) was explored for its probable application as an entrapment material concerning its degradation by enzymes in the colonic microflora and its drug release behavior in a sustained and controlled manner. INU is a polysaccharide and it consists of 2 to 1 linkage having an extensive array of beneficial uses such as a carrier for delivery of therapeutic agents as an indicative/investigative utensil or as a dietary fiber with added well-being aids. In the main, limited research, as well as information, is available on the delivery of therapeutic agents using inulin specifically for colon cancer because of its capability to subsist in the stomach's acidic medium. This exceptional steadiness and robustness properties are exploited in numerous patterns to target drugs securely for the management of colonic cancer, where they effectively act and kills colonic tumor cells easily. In this review article, recent efforts and inulin-based nano-technological approaches for colon cancer targeting are presented and discussed.

Tumour-Agnostic Therapy for Pancreatic Cancer and Biliary Tract Cancer

The prognosis of patients with solid tumours has remarkably improved with the development of molecular-targeted drugs and immune checkpoint inhibitors. However, the improvements in the prognosis of pancreatic cancer and biliary tract cancer is delayed compared to other carcinomas, and the 5-year survival rates of distal-stage disease are approximately 10 and 20%, respectively. However, a comprehensive analysis of tumour cells using The Cancer Genome Atlas (TCGA) project has led to the identification of various driver mutations. Evidently, few mutations exist across organs, and basket trials targeting driver mutations regardless of the primary organ are being actively conducted. Such basket trials not only focus on the gate keeper-type oncogene mutations, such as HER2 and BRAF, but also focus on the caretaker-type tumour suppressor genes, such as BRCA1/2, mismatch repair-related genes, which cause hereditary cancer syndrome. As oncogene panel testing is a vital approach in routine practice, clinicians should devise a strategy for improved understanding of the cancer genome. Here, the gene mutation profiles of pancreatic cancer and biliary tract cancer have been outlined and the current status of tumour-agnostic therapy in these cancers has been reported.

Genetic architecture of colorectal cancer

Colorectal cancer (CRC) is a complex disease that develops as a consequence of both genetic and environmental risk factors. A small proportion (3-5%) of cases arise from hereditary syndromes predisposing to early onset CRC as a result of mutations in over a dozen well defined genes. In contrast, CRC is predominantly a late onset 'sporadic' disease, developing in individuals with no obvious hereditary syndrome. In recent years, genome wide association studies have discovered that over 40 genetic regions are associated with weak effects on sporadic CRC, and it has been estimated that increasingly large genome wide scans will identify many additional novel genetic regions. Subsequent experimental validations have identified the causally related variant(s) in a limited number of these genetic regions. Further biological insight could be obtained through ethnically diverse study populations, larger genetic sequencing studies and development of higher throughput functional experiments. Along with inherited variation, integration of the tumour genome may shed light on the carcinogenic processes in CRC. In addition to summarising the genetic architecture of CRC, this review discusses genetic factors that modify environmental predictors of CRC, as well as examples of how genetic insight has improved clinical surveillance, prevention and treatment strategies. In summary, substantial progress has been made in uncovering the genetic architecture of CRC, and continued research efforts are expected to identify additional genetic risk factors that further our biological understanding of this disease. Subsequently these new insights will lead to improved treatment and prevention of colorectal cancer.

Methionine synthase A2756G polymorphism and risk of colorectal adenoma and cancer: evidence based on 27 studies

Methionine synthase (MTR), which plays a central role in maintaining adequate intracellular folate, methionine and normal homocysteine concentrations, was thought to be involved in the development of colorectal cancer (CRC) and colorectal adenoma (CRA) by affecting DNA methylation. However, studies on the association between MTR A2756G polymorphism and CRC/CRA remain conflicting. We conducted a meta-analysis of 27 studies, including 13465 cases and 20430 controls for CRC, and 4844 cases and 11743 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.03 (95% CI: 0.96-1.09) and 1.05 (95% CI: 0.99-1.12) for CRA. No significant results were observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. In the stratified analyses according to ethnicity, source of controls, sample size, sex, and tumor site, no evidence of any gene-disease association was obtained. Results from the meta-analysis of four studies on MTR stratified according to smoking and alcohol drinking status showed an increased CRC risk in heavy smokers (OR = 2.06, 95% CI: 1.32-3.20) and heavy drinkers (OR = 2.00, 95% CI: 1.28-3.09) for G allele carriers. This meta-analysis suggests that the MTR A2756G polymorphism is not associated with CRC/CRA susceptibility and that gene-environment interaction may exist.

Mouse models of gastric cancer

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

Molecular pathways in colorectal cancer

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

Absence of association between N-acetyltransferase 2 acetylator status and colorectal cancer susceptibility: based on evidence from 40 studies

BACKGROUND AND OBJECTIVES

N-Acetyltransferase (NAT) 2 is an important enzyme involved in the metabolism of different xenobiotics, including potential carcinogens, whose phenotypes were reported to be related to individual susceptibility to colorectal cancer (CRC). However, the results remain conflicting. To assess the relationship between NAT2 phenotypes and CRC risk, we performed this meta-analysis.

METHODS

A comprehensive literature search was conducted to identify all case-control or cohort studies of NAT2 acetylator status on the susceptibility of CRC by searching of PubMed and EMBASE, up to May 20, 2011. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the association.

RESULTS

A total of over 40,000 subjects from 40 published literatures were identified by searching the databases. No significantly elevated CRC risk in individuals with NAT2 slow acetylators compared with fast acetylators was found when all studies pooled (OR = 0.95, 95% CI: 0.87-1.04, I(2) = 52.6%). While three studies contributed to the source of heterogeneity were removed, there was still null result observed (OR = 0.96, 95% CI: 0.90-1.03, P = 0.17 for heterogeneity, I(2) = 17.8%). In addition, we failed to detect any associations in the stratified analyses by race, sex, source of controls, smoking status, genotyping methods or tumor localization. No publication bias was observed in this study.

CONCLUSIONS

This meta-analysis suggests that the NAT2 phenotypes may not be associated with colorectal cancer development.

The association of NAT1 polymorphisms and colorectal carcinoma risk: evidence from 20,000 subjects

Published data on the association between N-acetyltransferase 1 (NAT1) gene polymorphisms and colorectal carcinoma (CRC) susceptivity are inconclusive. To derive a more precise estimation of the association, we conducted this meta-analysis. Data were collected from electronic databases: PubMed, EMBASE, with the last report up to May 2010. The odds ratio (OR) and corresponding 95% confidence intervals (CIs) were used to assess the strength of the association. A total of 20 individual studies including 8,219 cases and 11,498 controls based on the search criteria were involved. Meta-analysis was performed for slow versus rapid acetylation genotypes of NAT1. We found no association between NAT1 polymorphisms and CRC in overall population (OR = 0.96, 95% CI = 0.88-1.05 P = 0.05 for heterogeneity) without significant publication bias present. In subgroup analyses, similar results were found in different ethnicities, source of controls, genotyping methods and adjustment. Current meta-analysis suggests that lack of association between the NAT1 polymorphisms and individual risk to CRC.

Performance of Lynch syndrome predictive models in a multi-center US referral population

OBJECTIVES

Lynch syndrome is the most common cause of inherited colorectal cancer (CRC) and is due to germline mutations in mismatch repair (MMR) genes. Early Lynch syndrome diagnosis and appropriate CRC surveillance improves mortality. Traditional qualitative clinical criteria including Amsterdam and Bethesda guidelines may miss mutation carriers. Recently, quantitative predictive models including MMRPredict, PREMM(1,2,6), and MMRPro were developed to facilitate diagnosis. However, these models remain to be externally validated in the United States. Therefore, we evaluated the test characteristics of Lynch syndrome predictive models in a tertiary referral group at two US academic centers.

METHODS

We retrospectively collected data on 230 consecutive individuals who underwent genetic testing for MMR gene mutations at the University of Chicago and University of California at San Francisco's Cancer Risk Clinics. Each individual's risk of mutation was examined using MMRPredict, PREMM(1,2,6), and MMRPro. Amsterdam and Bethesda criteria were also determined. Testing characteristics were calculated for each of the models.

RESULTS

We included 230 individuals in the combined cohort. In all, 113 (49%) probands were MMR mutation carriers. Areas under the receiver operator characteristic curves were 0.76, 0.78, and 0.82 for MMRPredict, PREMM(1,2,6), and MMRPro, respectively. While similar in overall performance, our study highlights unique test characteristics of these three quantitative models including comparisons of sensitivity and specificity. Moreover, we identify characteristics of mutation carriers who were missed by each model.

CONCLUSIONS

Overall, all three Lynch syndrome predictive models performed comparably in our multi-center US referral population. These results suggest that Lynch syndrome predictive models can be used to screen for MMR mutation carriers and can provide improved test characteristics compared with traditional clinical criteria. Identification of MMR mutation carriers is paramount as appropriate screening can prevent CRC mortality in this high-risk group.

[Colorectal cancer in familial adenomatous polyposis: Are there clinical predictive factors?]

BACKGROUND

Familial Adenomatous Polyposis (FAP) is a hereditary disorder with multiple colorectal polyps that exhibit an almost inevitable risk of colorectal cancer (CRC) in untreated patients.

GOALS

To evaluate clinical features related to CRC risk at diagnosis.

MATERIAL AND METHODS

Charts from 88 patients were reviewed to collect information regarding age, family history, symptoms, polyposis severity and association with CRC.

RESULTS

41 men (46.6%) and 47 women (53.4%) were assisted. CRC was detected in 53 patients (60.2%), with a frequency of 9.1% under 20 years, 58% between 21-40 and 85% over 41 years of age. Average age of patients without CRC was lower at treatment (29.5 vs. 40.0 years; p=0.001). Family history was reported by 58 patients (65.9%), whose average age did not differ from those who didn't report it (33.4 vs. 34.4; p=0.17). Asymptomatic patients comprised 10.2% of the total; in this group, CRC incidence was much lower when compared to those presenting symptoms (1.1% vs. 65.8%; p=0.001). Patients without CRC presented a shorter length of symptoms (15.2 vs. 26.4 months; p=0.03) and less frequent weight loss (11.4% vs. 33.9%; p=0.01). At colonoscopy, polyposis was classified as attenuated in 12 patients (14.3%), who presented greater average age (48.2 vs. 33.3 years; p=0.02) and equal CRC incidence (58.3% vs. 58.3%; p=0.6) when compared to those with classic polyposis.

CONCLUSIONS

The risk of CRC in FAP patients 1) increases significantly after the second decade; 2) is associated with higher age, weight loss, presence and duration of simptomatology; 3) is similar in patients with attenuated or classic phenotype.

Association of microRNA expression with microsatellite instability status in colorectal adenocarcinoma

MicroRNAs (miRNA), small noncoding RNAs, are potential diagnostic and prognostic markers, as well as therapeutic targets. miRNA profiles of colorectal carcinomas have not been studied extensively in the context of microsatellite instability (MSI) status. We therefore evaluated 55 paired colorectal adenocarcinomas (CRC) and non-neoplastic mucosa samples using a panel of 24 miRNAs selected by literature review and prior studies in our laboratory. Stem-loop reverse transcriptase quantitative (real-time) polymerase chain reaction assays were done on RNA extracted from formalin-fixed, paraffin-embedded tissue of resection specimens. When miRNA expression was compared with clinicopathologic features and MSI status, eleven miRNAs (miR-183, -31, -20, -25, -92, -93, -17, -135a, -203, -133b, and -223) were over-expressed in CRC relative to mucosa, and nine (miR-192, -215, -26b, -143, -145, -191, -196a, -16, and let-7a) were under-expressed in CRC. Relative expression of miR-92, -223, -155, -196a, -31, and -26b were significantly different among MSI subgroups, and miR-31 and miR-223 were overexpressed in CRC of patients with hereditary non-polyposis colorectal cancer syndrome (Lynch syndrome). Our findings indicate that miRNA expression in CRC is associated with MSI subgroups, including low MSI and HNPCC-associated cancers, and that miRNAs may have posttranscriptional gene regulatory roles in these MSI subgroups and possible effects on the clinicopathologic and biomarker characteristics.

The impact of family history on the outcome of patients with colorectal cancer in a veterans' hospital

PURPOSE

The purpose of the study was to investigate the impact of a family history (FH) of colorectal cancer (CRC) in first-degree relatives on the outcome of patients with CRC in a veterans' hospital in Taiwan.

METHODS

Patients (N = 3,383) with colorectal adenocarcinoma were studied; pedigrees were collected prospectively. Associations between FH and clinicopathologic variables were analyzed using linear-by-linear association. Survival was examined with Kaplan-Meier curves and the log-rank test.

RESULTS

Two hundred ninety-seven patients (8.78%) had a first-degree relative with CRC. The average age of onset of CRC was 68.3 years in patients without a FH. This was significantly higher than the age of onset in patients with a FH (66.4 years--one first-degree relative with CRC; 48.8 years--two or more first-degree relatives, P < 0.001). Patients with more affected family members had a higher incidence of right-sided tumor (P = 0.004), metachronous cancer (P = 0.034), and less-advanced disease (P = 0.044). The 5-year overall survival was 83% for patients with two or more first-degree relatives with CRC, 57% for those with one first-degree relative, and 55% for those without a FH (P = 0.001). The 5-year DFS was 91% for patients with two or more first-degree relatives, 66% for those with one first-degree relative, and 64% for those without a FH of CRC (P = 0.002). In the multivariate analysis, TNM stage played the most independent prognostic factor, followed by FH (P < 0.001, hazard ratio = 1.52; 95% confidence interval, 1.24-1.85).

CONCLUSIONS

CRC patients with a family history of CRC had better survival than did those without a family history of CRC.

Towards identification of hereditary DNA mismatch repair deficiency: sebaceous neoplasm warrants routine immunohistochemical screening regardless of patient's age or other clinical characteristics

Although the significance of immunohistochemical detection of DNA mismatch repair proteins and/or microsatellite instability testing in identifying patients at risk for germline deficiency in DNA mismatch repair genes is well established in colorectal carcinomas, the proper use of such techniques in sebaceous neoplasms, another tumor type that has been implicated in patients with hereditary DNA mismatch repair deficiency, has not been clearly defined. In this study, we stratified a series of 27 patients with 1 or more sebaceous neoplasms based on the pattern of immunohistochemical expression of MLH1, MSH2, MSH6, and PMS2, and comparatively analyzed their clinical and pathologic characteristics, including tumor-infiltrating lymphocytes and peritumoral lymphocytic response as determined by immunohistochemical staining for CD3. The study tissue samples included 30 sebaceous carcinomas, 14 sebaceous adenomas, and 7 sebaceous hyperplasias, along with 8 concurrent nonsebaceous lesions from 6 patients. Overall, 12 of the 27 (44%) patients showed abnormal IHC staining with mismatch repair proteins in their sebaceous tumors, the most commonly seen abnormality being concurrent loss of MSH2 and MSH6 (8/12, 67%). Sebaceous adenomas and carcinomas occurring in the same patients showed an identical staining pattern, as did hereditary nonpolyposis colorectal cancer-related nonsebaceous tumors in the same patients. When compared with cases that had normal expression of the mismatch repair proteins, cases with abnormal expression tended to be younger (median age, 56.5 y vs. 68 y), more likely to involve sites outside the head and neck (9/12 vs. 0/15), and more likely to have synchronous or metachronous visceral malignancies (8/12 vs. 3/15) and a positive family history. Furthermore, sebaceous tumors with abnormal expression had significantly higher CD3-positive tumor-infiltrating lymphocytes and peritumoral lymphocytic response. Thus, all these factors (age less than 60 y, involvement of nonhead and neck sites, visceral malignancy, family history fulfilling at least Bethesda guidelines, and lymphocytic infiltration) bore informative value in predicting abnormal expression of DNA mismatch repair proteins. However, their sensitivity was only modest, being 58%, 75%, 67%, 78%, and 75%, respectively. On such a premise, given that sebaceous neoplasms are only infrequently encountered, and that immunohistochemistry is easily available and reasonably reliable, we recommend that, when there exists a desire to identify hereditary DNA mismatch repair deficiency, routine immunohistochemical detection of DNA mismatch repair proteins be performed in all sebaceous neoplasms regardless of patient's age or other clinical characteristics.

Article Commentary: Surgical Prophylaxis for Inheritable Malignant Diseases: Colorectal and Gastric Cancer

Despite advances in modern medicine, cancer remains all too common and deadly. At its core, cancer is a disease of our DNA. As such, many cancers are passed from parents to children, making cancer one of the most commonly inherited diseases. Presently, we have no meaningful methods of “preventing” the malignant transformation that occurs as a result of an inherited gene, but investigators have identified several genetic mutations and subsequently developed risk-reduction strategies that sometimes involve surgery.

A comparison of models used to predict MLH1, MSH2 and MSH6 mutation carriers

BACKGROUND

MMRpro, prediction of mutations in MLH1 and MLH2 (PREMM(1,2)) and MMRpredict are models which were developed to predict the probability that an individual carries a Lynch syndrome-causing mutation. Each model utilizes data from personal and family histories of cancer. To date, no studies have compared these models in a cancer genetics clinic. The purpose of this study was to determine each model's ability to predict the probability of carrying a Lynch syndrome-causing mutation in individuals with a family history of colorectal cancer and to determine their clinical applicability.

METHODS

We obtained family pedigrees from 81 individuals who presented for Lynch syndrome testing due to a personal and/or family history of cancer. Data from each pedigree were entered into the models and analyzed using SPSS.

RESULTS

We found that MMRpredict, PREMM(1,2) and MMRpro showed similar performances with areas under the receiver-operating characteristic curve of 0.731, 0.765 and 0.732, respectively. MMRpro showed the least dispersion of mutation probability estimates with a P value of 0.205, compared with 0.034 for PREMM(1,2) and 0.001 for MMRpredict.

CONCLUSION

We found all three carried out well in a cancer genetics setting, with PREMM(1,2) giving slightly better estimates. There were some significant discrepancies between the models in cases where the proband had endometrial cancer.