The cause of colorectal cancer

Early onset sporadic colorectal cancer: Worrisome trends and oncogenic features

Early onset colorectal cancers, defined as arising before 50 years of age, are a growing health hazard in western and eastern countries alike. The incidence of colon and rectal cancers in young individuals is projected to increase by as much as 90% and 140%, respectively, by 2030. Although several known cancer risk factors (e.g. smoking, alcohol, dietary habits) have been investigated, there is no single compelling explanation for this epidemiological trend. While some early onset colorectal cancers have been associated with germline mutations in cancer predisposition genes, genetic syndromes are implicated in only a fraction of these cancers (20%) and do not explain the rising incidence. Colorectal neoplasms develop through microsatellite instability or chromosomal instability pathways, with most of the early onset colorectal cancers exhibiting microsatellite stable phenotypes. Genome-wide hypomethylation is a feature of a subgroup of early onset cancers, which appears to be correlated with chromosomal instability and poor prognosis.

Regional Estimates of Colorectal Cancer Burden in Italy

Aims and background

In terms of new diagnoses, colorectal cancer is one of the most important cancers in Italy and worldwide. The aim of this paper is to present estimates of the mortality, incidence and prevalence of colorectal cancer in Italy at a national and regional scale over the period 1970-1999, with projections up to 2010.

Methods

The estimates were obtained by applying the MIAMOD method, a statistical back-calculation approach to derive incidence and prevalence estimates from mortality and relative survival data. Published data from the Italian cancer registries were modelled to obtain regional and national estimates of colorectal cancer survival.

Results

Different incidence patterns were observed for men and women, especially in the projection period: the national age-standardized rate is estimated to increase throughout the study period 1970-2010 for men from 30 to 70 per 100,000, and to stabilize from the end of the 1990s for women at around 38 per 100,000. A stabilization or a slight decrease in age-standardized incidence rates is expected in most regions for women and in most northern-central regions for men. The most critical situation is estimated among men for southern regions, where the rise in incidence is accompanied by a dramatic increase in mortality. About 46,000 incident cases, 267,000 prevalent cases, and 16,000 deaths from colorectal cancer are estimated in Italy for the year 2005.

Conclusions

Despite the risk reduction estimated in most northern-central regions among men and in the large majority of regions among women, the colorectal cancer burden in Italy is expected to remain relevant in the next years. Prospects for reducing this burden appear mainly connected to the adoption of prevention policies aimed at increasing the awareness of the risk related to dietary habits and lifestyles and at promoting colorectal cancer screening.

Vitamin and multiple-vitamin supplement intake and incidence of colorectal cancer: a meta-analysis of cohort studies

This paper systematically evaluated the association of intake of different vitamins and multiple-vitamin supplements and the incidence of colorectal cancer. Relevant studies were identified in MEDLINE via PubMed (published up to April 2014). We extracted data from articles on vitamins A, C, D, E, B9 (folate), B2, B3, B6, and B12 and multiple-vitamin supplements. We used multivariable-adjusted relative risks (RRs) and a random-effects model for analysis and random effects. With heterogeneity, we looked for the source of heterogeneity or performed sensitivity and stratified analyses. We found 47 articles meeting the inclusion criteria. The multivariable-adjusted RR for pooled studies for the association between the highest versus lowest vitamin B9 (folate) intake and colorectal cancer was 0.88 [95 % confidence interval (95 % CI) 0.81-0.95]. Vitamin D was 0.87 (95 % CI 0.77-0.99); vitamin B6, 0.88 (95 % CI 0.79-0.99); vitamin B2, 0.86 (95 % CI, 0.76-0.97); vitamin A, 0.87 (95 % CI, 0.75-1.03); vitamin C, 0.92 (95 % CI, 0.80-1.06); vitamin E, 0.94 (95 % CI, 0.82-1.07); vitamin B12, 1.10 (95 % CI, 0.92-1.32); vitamin B3, 1.18 (95 % CI, 0.76-1.84). Vitamin B9 (folate), D, B6, and B2 intake was inversely associated with risk of colorectal cancer, but further study is needed. Our study featured unacceptable heterogeneity for studies of multiple-vitamin supplements, so findings were inconclusive.

Colorectal cancer in Italy: a review of current national and regional practice on screening and treatment

Colorectal cancer (CRC) is one of the most prevalent and deadly cancers in Italy. Its burden is expected to remain significant in the coming years, although it is mostly a preventable disease. Prevention and screening programmes will play an important role in the fight against CRC. A national formal screening programme was introduced in the 2003-2005 and 2005-2007 national health programmes, leaving the planning and implementation, respectively, to each region and local health unit. In 2007, screening programmes covered 46.6% of the eligible population, with a higher coverage in the North (71.6%) and in the Centre (52.1%) than in the South (7%). The majority of programmes used the guaiac faecal occult blood test (FOBT) as first-line test. Only few programmes used the flexible sigmoidoscopy, or a combination of both tests. The quality and efficacy of the screening programmes are evaluated using ad hoc indicators with acceptable and desirable targets. In Italy, there are formal guidelines for population-based and opportunistic screening, diagnosis, surgery, adjuvant and neoadjuvant treatments and surveillance, differentiating colon cancer from rectal cancer and advanced CRC. Guidelines are updated yearly. Overall, Italy is well positioned in the fight against CRC. Although many regions lag behind in the uptake of screening programmes, they are in the process of introducing them.

Detection of colonic polyps according to insertion/withdrawal phases of colonoscopy

BACKGROUND AND AIMS

Issues on colonoscopy quality are crucial to reduce the advanced neoplasia miss rate of colonoscopy. Recently, a >6-min withdrawal time has been recommended. However, the relative prevalence of polyp detected during insertion and withdrawal phases of colonoscopy is unknown. Therefore, we designed this prospective, endoscopic study.

MATERIALS AND METHODS

Three hundred and sixty-eight patients with 396 adenomas were selected from a consecutive colonoscopic series of 1,205 cases. Detection rates of adenomas, advanced adenomas, and cancer according to withdrawal and insertion phases of colonoscopy, also subgrouping polyps for size and location, were compared.

RESULTS

Thirty-two (74%) advanced adenomas and 21 (95%) cancers were detected during the insertion, being only 11 (26%) and one (5%) identified during withdrawal, respectively. This was mainly due to a higher detection of >10 mm polyps during insertion than during withdrawal (75% versus 25%).

CONCLUSIONS

Most advanced neoplasia are detected during the insertion. Although withdrawal time has been shown to be important, the scope insertion phase related to polyp detection should be specifically addressed.

Diverticulosis and colorectal cancer: between lights and shadows

The prevalence of diverticulosis and colorectal cancer (CRC) is markedly increased in the last century. Both diseases are highly frequent in Western countries and in aged people. Western diet--low in fiber and rich in dietary fat--has been largely regarded to play a major role in the pathogenesis of both conditions. A causal relationship between diverticulosis and CRC has been suggested in different studies. Epidemiologic series found a more frequent rectosigmoid localization of neoplastic lesions (advanced adenoma and CRC) in patients with diverticulosis as compared with controls, particularly in those with a previous diverticulitis episode or with an extensive disease. However, data are still controversial, with other studies failing to confirm this observation. Such discrepancy could be referred to the highly heterogeneous study design and setting in the different epidemiologic series. Pathologic studies showed that either macroscopic and microscopic chronic inflammation--which is regarded as risk factor for CRC development--is present in the colonic mucosa of some patients with diverticula. Moreover, alterations in the extracellular matrix, also involved in colorectal carcinogenesis, have been depicted in diverticulosis. In addition, an upward shifting of cell proliferation occurs in diverticular mucosa, and in nondiverticular patients with advanced adenomas. Finally, aberrant crypt foci--which are considered potential markers of CRC risk in ulcerative colitis--have been detected in colonic mucosa of patients with diverticulosis. Despite this substantial amount of evidence, however, the available data are not yet strong enough to suggest a more aggressive CRC prevention in diverticular as compared with nondiverticular subjects.

From cell signaling to cancer therapy

Cancer has been seriously threatening the health and life of humans for a long period. Despite the intensive effort put into revealing the underlying mechanisms of cancer, the detailled machinery of carcinogenesis is still far from fully understood. Numerous studies have illustrated that cell signaling is extensively involved in tumor initiation, promotion and progression. Therefore, targeting the key molecules in the oncogenic signaling pathway might be one of the most promising ways to conquer cancer. Some targeted drugs, such as imatinib mesylate (Gleevec), herceptin, gefitinib (Iressa), sorafenib (Nexavar) and sunitinib (Sutent), which evolve from monotarget drug into multitarget ones, have been developed with encouraging effects.

Gene expression profiling in familial adenomatous polyposis adenomas and desmoid disease

Gene expression profiling is a powerful method by which alterations in gene expression can be interrogated in a single experiment. The disease familial adenomatous polyposis (FAP) is associated with germline mutations in the APC gene, which result in aberrant β-catenin control. The molecular mechanisms underlying colorectal cancer development in FAP are being characterised but limited information is available about other symptoms that occur in this disorder. Although extremely rare in the general population, desmoid tumours in approximately 10% of FAP patients. The aim of this study was to determine the similarities and differences in gene expression profiles in adenomas and compare them to those observed in desmoid tumours. Illumina whole genome gene expression BeadChips were used to measure gene expression in FAP adenomas and desmoid tumours. Similarities between gene expression profiles and mechanisms important in regulating formation of FAP adenomas and desmoid tumours were identified. This study furthers our understanding of the mechanisms underlying FAP and desmoid tumour formation.

The colorectal malignant polyp: scoping a dilemma

Colorectal adenomas containing invasive carcinoma represent the majority of early colorectal cancers. The malignant polyp carries a significant risk of lympho-haematic metastasis and mortality due to the penetration of cancerous cells into the submucosal layer. The therapeutic dilemma is whether to perform endoscopic or surgical resection. A thorough assessment of the endoscopic, histological and clinical variables is needed to unravel the best treatment for each patient. In particular, a unique staging of such lesions, based on certain histopathological features, has been deeply implicated in the therapeutic choice. Aim of this article is to review the main endoscopic, histological and clinical features of the malignant polyp in order to propose a systematic management of this lesion.

Chromosome alterations in colorectal cancer in Thai patients

Much information has been reported on the genetic and genomic alterations in colorectal cancer (CRC) in various countries; however, nonrandom chromosomal alterations in Thai patients have not been described. As a first step toward understanding the underlying genetic changes and determining early chromosomal changes of tumor development in this population, we used comparative genomic hybridization (CGH) to screen for losses and gains of DNA sequences along chromosomes in 20 morphologically normal tumor surroundings (MNTS) and 40 CRC tissues from 40 patients. In CRC, we detected gains of chromosome arms 20q (60%), 8q (25%), 19q (22.5%), and 19p (20%), as well as losses of chromosome arms 18q (25%) and 4q (20%). There were no differences in genetic alteration between colon and rectal cancer. In morphologically normal tumor surroundings (MNTS) tissues, gains on 19p and 19q were most frequent. We suggest that gains of this chromosome are early events in the progression of CRC, followed by gains on 8q and 20q and losses on 4q and 18q at later stages. Based on our cytogenetic data by comparison of 2 tissue groups in the same cases, we discuss the monoclonal model followed by lateral epithelial spread as an explanation of multiple CRC. Identification and characterization of the causative genes for these cancer syndromes have enabled precise pre-symptomatic detection of mutations in individuals who bear a prior risk of developing CRC.

Serum bile acids, programmed cell death and cell proliferation in the mucosa of patients with colorectal adenomas

BACKGROUND

Deoxycholic acid induced programmed cell death and an imbalance with cell proliferation may favour colorectal tumourigenesis according to 'in vitro' studies, but information is lacking on the relationships occurring 'in vivo' in humans.

AIMS

To evaluate whether serum deoxycholic acid is associated with programmed cell death and cell proliferation in colonic mucosa.

METHODS

In 10 patients with colorectal adenomas, we measured fasting serum levels of bile acids; and, in normal colonic mucosa, programmed cell death by the TUNEL technique and cell proliferation by immunohistochemical staining with anti-Ki67. Total and compartmental indices for both activities were calculated.

RESULTS

Among serum bile acids, only total deoxycholic acid (median: 0.89 micromol/L +/- 0.54 95% CI), showed a significant positive correlation with the total and basal compartments PCD Index (r = 0.68, p < 0.05). Total proliferation index showed no correlation with either total PCD Index, or bile acids. Within the median compartment of the crypt, cell proliferation was negatively associated with all unconjugated bile acids.

CONCLUSIONS

The positive association between deoxycholic acid and programmed cell death in the basal compartment of the crypt, and the negative association of cell proliferation and unconjugated bile acids in the median compartment, do not seem to support the co-carcinogenic effect of deoxycholic acid.

Diverticular disease as a risk factor for sigmoid colon adenomas

BACKGROUND

Diverticular disease and colorectal neoplasia share similar epidemiological features and risk factors.

AIM

To evaluate a possible association between diverticular disease and both adenomas and colorectal cancer in patients undergoing total colonoscopy.

METHODS

Overall, 630 consecutive patients were recruited from the 3 Units. Inclusion criteria were age over 45 years and the performance of total colonoscopy. Demographic and clinical data were recorded. Adenomas were defined as advanced when their size was >1 cm in diameter, and/or the percentage of the villous component was >30% and/or high grade dysplasia was present.

RESULTS

At endoscopy, 291 (47%) out of 630 patients presented evidence of diverticular disease. Adenomas were found in 92 (31.9%) patients with diverticular disease and in 98 (28.9%) patients without [p=ns]. The prevalence of adenomas located in the sigmoid colon was significantly higher in patients with diverticula than in controls (64.1% vs 41.8%; p<0.05). Similarly, the detection of advanced adenomas located in the sigmoid colon was more likely in patients with diverticula than in controls (59.6% vs 37.5%; p<0.05). Colorectal cancer prevalence was similar in patients with and without diverticula (8.3% vs 7.1%; p=ns), and no difference was detected regarding site, between the two groups.

CONCLUSIONS

Patients with diverticular disease have a higher risk of harbouring adenomas and advanced adenomas in the sigmoid colon. This observation should be taken into account in screening and surveillance programmes for colorectal neoplasia.

Diet and cancer: assessing the risk

Globally, colorectal cancer (CRC) is a leading cause of mortality from malignant disease. Case-control and cohort studies provide strong support for a role of diet in the aetiology of CRC. However to establish causal relationships and to identify more precisely the dietary components involved, intervention studies in human subjects are required. Cancer is an impractical endpoint in terms of numbers, cost, study duration and ethical considerations. Consequently, intermediate biomarkers of the disease are required. This review aims to provide an overview of the intermediate endpoints available for the study of CRC, particularly non-invasive faecal biomarkers. Examples of their use in dietary intervention studies are given.

Prevention and chemoprevention of colorectal neoplasms

Main purpose of the review is to analyse the impact of the current approaches for colorectal cancer prevention, including chemoprevention. Available evidence does not support the contention that a more appropriate diet can be of great help in the prevention of these neoplasms, either because the scientific evidence is poor and highly controversial, or because changes in diet are difficult to implement, at least in many Western countries. Similarly, a preventive approach based on the modification of lifestyle remains improbable, either in the short --or in the long period of time. Secondary prevention--i.e., the systematic removal of adenomatous polyps--can hardly be applied in the general population, with the exception of individuals at risk because members of families with Adenomatosis coli or Lynch syndrome, or affected by inflammatory bowel diseases. Finally, chemoprevention (i.e., the attempt to prevent tumour development through the administration of drugs or natural compounds that interfere with various phases of carcinogenesis) is still in its infancy Though attractive, this approach requires well-designed studies which should be carried out for years before being evaluated and interpreted; so far most of these investigations gave inconsistent or controversial results. In conclusion, both primary and secondary prevention of colorectal malignancies appear difficult to apply in the general population, and chemoprevention is still at the beginning of a (presumably] long story. The final impression is that notwithstanding the remarkable advancements made in the last two decades in colorectal cancer research, the practical application of these new concepts remains difficult.

Pathology of colorectal cancer

The earliest phases of colorectal tumourigenesis initiate in the normal mucosa, with a generalised disorder of cell replication, and with the appearance of clusters of enlarged crypts (aberrant crypts) showing proliferative, biochemical and biomolecular abnormalities. The large majority of colorectal malignancies develop from adenomatous polyps. These can be defined as well demarcated masses of epithelial dysplasia, with uncontrolled crypt cell division. An adenoma can be considered malignant when neoplastic cells pass through the muscularis mucosae and infiltrate the submucosa. Definitions like "carcinoma in situ" or "intramucosal carcinoma" should be abandoned, since they lead to confusion. Although several lines of evidence indicate that carcinomas usually originate from pre-existing adenomas, this does not imply that all polyps undergo malignant changes, and does not exclude "de novo" carcinogenesis. Besides adenomas, other types of polypoid lesions include hyperplastic polyps (showing elongated crypts often with cystic dilatation), serrated adenomas (with a serrated glandular pattern], flat adenomas (flat lesions which are difficult to detect in routine lower endoscopy, but may possess malignant potential), hamartomatous polyps (which show a complex branching pattern of smooth muscle supporting normal lamina propria and glands), and inflammatory polyps. Colorectal carcinomas are one of the most frequent neoplasms in Western society; the macroscopic appearance of these lesions may be that of a polypoid vegetating mass or of a flat infiltrating lesion. Most of these tumours are adenocarcinomas (96%), that, in some cases, show a mucinous component. More rare malignancies of the large bowel include signet-ring cell carcinoma, squamous carcinoma, undifferentiated neoplasms and medullary type adenocarcinoma (solid carcinoma with minimal glandular differentiation or slight cellular pleomorphism). Colorectal carcinoma can be graded into well, moderately and poorly differentiated lesions; there is little evidence, however, that grading may be of help in evaluating prognosis of affected patients. In conclusion, colorectal tumours cover a wide range of premalignant and malignant lesions, many of which can easily be removed at endoscopy. It follows that colorectal neoplasms might be prevented by interfering with the various steps of carcinogenesis, which begins with uncontrolled epithelial cell replication, continues with the formation of adenomas of various dimensions, and eventually evolves into malignancy.

Pathogenesis of colorectal cancer

The development of colorectal cancer has been viewed as an ordered process in which three main phases can be identified: initiation, promotion and progression. There is definite proof that stable alterations of the structure or sequence of DNA (mutations) represent the initiating event; these are followed by an uncontrolled expansion of the neoplastic clones which characterizes tumoural growth. Several classes of genes have been identified foncogenes, tumour suppressor genes and "mutator" genes) the alterations of which are important in the initiation as well as in the promotion and progression of tumours. Colorectal cancer, therefore, results from a series of genetic changes which lead to the progressive and irreversible loss of normal control of cell growth and differentiation. Available evidence is consistent with the hypothesis that there are several molecular pathways underlying the passage from normal mucosa to colorectal carcinoma, thus explaining the existence of intestinal tumours with a different biological nature, which may represent specific targets for prevention and cure. Well-defined molecular pathways have been identified for: A) sporadic colorectal cancer ("Loss of heterozygosity pathway"); B) familial adenomatous polyposis and related polyposis syndromes; C) hereditary non-polyposis colorectal cancer ("mutator genes/microsatellite instability pathway"); D) cancer developing in inflammatory bowel diseases; E) familial colorectal cancer. Thus, there is consistent and considerable evidence suggesting the existence of several biological pathways leading to the same phenotypical expression (i.e., colorectal cancer), and it is likely that additional pathways will be clarified in the future. From a practical point of view, tumours with a diverse biology might offer different and more effective preventive and curative approaches.