Rectal aberrant crypt foci identified using high-magnification-chromoscopic colonoscopy: biomarkers for flat and depressed neoplasia

Non-therapeutic plasma levels in individuals utilizing curcumin supplements in daily life

Introduction

The spice curcumin and its metabolites are widely used by cancer patients but have not shown proven health benefits in clinical studies, likely due to low plasma concentrations after oral intake. However, public interest in curcumin continues to grow, and companies claim enhanced absorption in their formulations. This study aims to determine if daily oral intake of curcumin leads to sufficient plasma concentrations for health effects. The study was registered in the Dutch Clinical Trial Register with ID NL5931.

Methods

We used a validated HPLC-MS/MS method to measure curcumin and its metabolites in 47 individuals using their own curcumin formulations. Questionnaires assessed other supplement and medication use. Plasma samples were collected before and 1.5 h after intake, analyzing curcumin and metabolite levels with and without β-glucuronidase pretreatment to measure conjugated and unconjugated forms.

Results

Plasma concentrations of curcumin, demethoxycurcumin, bisdemethoxycurcumin and tetrahydrocurcumin, ranged between 1.0 and 18.6 ng/mL. Adding β-glucuronidase resulted in an increase of unconjugated curcumin plasma levels to 25.4 ng/mL; however still significantly below (1000-fold) a plasma concentration that is expected to have a beneficial health effect. The use of adjuvants like piperine did not result in higher curcumin plasma concentrations.

Discussion

Our study shows that using oral curcumin supplements still does not result in therapeutic plasma levels. Health care practitioners need to be critical toward the claimed beneficial systemic health effects of current curcumin supplement use by their patients.

Clinical Trial Registration

https://onderzoekmetmensen.nl/en/trial/25480, NL5931.

The Effect of Low Doses of Acetylsalicylic Acid on the Occurrence of Rectal Aberrant Crypt Foci

Background and Objectives: Aberrant crypt foci (ACF) are one of the earliest putative preneoplastic and, in some cases, neoplastic lesions in human colons. Many studies have confirmed the reduction of ACFs and colorectal adenomas after treatment with acetylsalicylic acid (ASA) commonly referred to as ASA; however, the minimum effective dose of ASA and the duration of use has not been fully elucidated. The objective of our study was to assess the significance of low dose ASA (75-mg internally once daily) to study the chemopreventive effect of ASA in ACF and adenomas development in patients taking this drug for a minimum period of 10 years. Materials and Methods: Colonoscopy, combined with rectal mucosa staining with 0.25% methylene blue, was performed on 131 patients. The number of rectal ACF in the colon was divided into three groups: ACF < 5; ACF 5−10; and ACF > 10. Patients were divided into two groups: the “With ASA” group (the study group subjects taking ASA 75-mg daily for 10 years); and “Without ASA” group (control group subjects not taking ASA chronically). The incidence of different types of rectal ACF and colorectal polyps in both groups of subjects was analysed and ascertained. Results: Normal ACF was found in 12.3% in the study group vs. 87.7% control group, hyperplastic 22.4% vs. 77.6%, dysplastic 25% vs. 75%, mixed 0% vs. 100%. Treatment with ASA affects the occurrence of colorectal adenomas. The amount of dysplastic ACFs was lower in the study group than in the control group. The increase in dysplastic ACFs decreases with age in both groups, with the increase greater in those not taking ASA. Conclusions: Patients who take persistent, chronic (>10 years) low doses of ASA have a lower total number of all types of rectal ACFs and adenomas compared to the control group.

The Epithelial-Stromal Microenvironment in Early Colonic Neoplasia

Stromal cells play a central role in promoting the progression of colorectal cancer. Here, we analyze molecular changes within the epithelial and stromal compartments of dysplastic aberrant crypt foci (ACF) formed in the ascending colon, where rapidly developing interval cancers occur. We found strong activation of numerous neutrophil/monocyte chemokines, consistent with localized inflammation. The data also indicated a decrease in interferon signaling and cell-based immunity. The immune checkpoint and T-cell exhaustion gene PDCD1 was one of the most significantly upregulated genes, which was accompanied by a decrease in cytotoxic T-cell effector gene expression. In addition, CDKN2A expression was strongly upregulated in the stroma and downregulated in the epithelium, consistent with diverse changes in senescence-associated signaling on the two tissue compartments. IMPLICATIONS: Decreased CD8 T-cell infiltration within proximal colon ACF occurs within the context of a robust inflammatory response and potential stromal cell senescence, thus providing new insight into potential promotional drivers for tumors in the proximal colon.

Dysplastic Aberrant Crypt Foci: Biomarkers of Early Colorectal Neoplasia and Response to Preventive Intervention

The discovery of aberrant crypt foci (ACF) more than three decades ago not only enhanced our understanding of how colorectal tumors form, but provided new opportunities to detect lesions prior to adenoma development and intervene in the colorectal carcinogenesis process even earlier. Because not all ACF progress to neoplasia, it is important to stratify these lesions based on the presence of dysplasia and establish early detection methods and interventions that specifically target dysplastic ACF (microadenomas). Significant progress has been made in characterizing the morphology and genetics of dysplastic ACF in both preclinical models and humans. Image-based methods have been established and new techniques that utilize bioactivatable probes and capture histologic abnormalities in vivo are emerging for lesion detection. Successful identification of agents that target dysplastic ACF holds great promise for intervening even earlier in the carcinogenesis process to maximize tumor inhibition. Future preclinical and clinical prevention studies should give significant attention to assessing the utility of dysplastic ACF as the earliest identifiable biomarker of colorectal neoplasia and response to therapy.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

Rectal aberrant crypt foci (ACF) as a predictor of benign and malignant neoplastic lesions in the large intestine

Background

The importance of ACF is not fully explained, however, their number may be a good predictor of synchronous and metachronic adenoma or other polyps whose removal reduces the risk of CRC. Due to the epidemiological and genetic association of ACF with pre-cancer lesions, they may be a potential CRC biomarker. The aim of our study was to show that the number and type of rectal ACF may be a good predictive factor for the presence of polyps located proximally from the splenic flexure and that the type and number of ACF can correlate with the number and specific types of polyps in the large intestine.

Methods

The study included 131 patients who underwent colonoscopy combined with rectal mucosa staining with 0.25% methylene blue. The number of rectal ACF was determined and bioptats were sampled for histopathological examination to assess the type of ACF. Endoscopic ACF assessment criteria given by L. Roncucci were used. The obtained material was subjected to statistical analysis using probability distribution, U-test, t-student test, and chi ² as well as the Statistica 7.1 software package.

Results

The study population was divided into three subgroups according to the number of ACF observed, i.e. ACF < 5, 5–10 and > 10. ACF < 5 were found in 35 patients (29.41%), 5–10 ACF in 70 (58.82%) and ACF > 10 in 14 individuals (11.76%).

The study revealed the presence of normal ACF (p = 0.49), hyperplastic ACF (p = 0.34), dysplastic ACF (p = 0.11), and mixed ACF (p = 0.06). A single type of ACF was most commonly observed (n = 88, p = 0.74). In the researched group a larger number of ACF is concurrent with adenomas and hyperplastic polyps. The number of ACF clearly correlates with the dysplasia advancement in the adenoma and the number of polyps found.

Conclusions

Rectal ACF are a useful marker for the presence of cancerous lesions in the proximal and distal sections of the large intestine.

Rectal Aberrant Crypt Foci in Humans Are Not Surrogate Markers for Colorectal Cancer Risk

INTRODUCTION

Over the past 20 years, aberrant crypt foci (ACF) have emerged as potential precursors and biomarkers for colorectal cancer (CRC). However, data regarding their molecular pathogenesis, as well as their endoscopic and histological identification, remain inconsistent.

METHODS

A wide cohort of ACF from 100 control subjects and 100 case patients, including patients with adenoma and CRC, were characterized for endoscopic, morphologic, and molecular features.

RESULTS

We observed that among all the endoscopic features evaluated, only the number of large ACF correlated with CRC risk (P = 0.003), whereas the histological classification, as assessed by 2 different pathologists, was inconsistent and did not differ between control and case patients. Moreover, only a few APC and BRAF mutations and no microsatellite instability were detected in our samples. KRAS mutations were detected in 16.3% of ACF samples, which also exhibited increased MGMT hypermethylation. However, none of those events were found to be predictive of CRC risk.

DISCUSSION

Although ACF might be preneoplastic lesions of the colon, they are not suitable biomarkers for assessing CRC progression.

Occurrence of colorectal aberrant crypt foci depending on age and dietary patterns of patients

Background

Aberrant crypt foci (ACF) are commonly considered the early pre-cancerous lesions that can progress to colorectal cancer (CRC). The available literature data reveal that age, dietary factors and lifestyle can affect the development of several dozen percentages of malignant tumours, including CRC. In the present study, an attempt was made to assess the incidence and growth dynamics of ACF and to determine whether the type of diet affected the development and number of AFC.

Methods

Colonoscopy combined with rectal mucosa staining with 0.25% methylene blue was performed in 131 patients. On the day of examination, each patient completed a questionnaire regarding epidemiological data. According to their numbers, colorectal ACF were divided into three groups. The findings were analysed statistically. The Student’s t test and the U test were applied in order to determine the significance of differences of means and frequency of events in both groups. Statistica 7.1 and Excel 2010 were used.

Results

The single ACF occur in the youngest individuals (ACF < 5). Since the age of 38 years, the number of ACF gradually increases to show a decreasing tendency since the age of 60 years. The number of 5 < ACF < 10 occurs slightly later, since the age of 50 years, and dynamically increases reaching the maximum at the age of 62 years, subsequently the increase is proportional. ACF > 10 occur at a more advanced age (55 years) and their number gradually increases with age. The maximum number is observed at the age of 77 years.

In individuals not using high-fibre diets and with high intake of red meat, the probability of higher numbers of ACF increases. The probability of higher numbers of ACF (5 < ACF10) was observed in patients with colon diverticula. In patients with higher BMI, the number of ACF is higher.

Conclusion

Age significantly affects the number of colorectal ACF. The types of foods consumed can considerably increase the risk of colorectal ACF, which is particularly visible in individuals who do not regularly use high-fibre diets, those obese and with colon diverticula.

Chronic Trichuris muris infection causes neoplastic change in the intestine and exacerbates tumour formation in APC min/+ mice

Incidences of infection-related cancers are on the rise in developing countries where the prevalence of intestinal nematode worm infections are also high. Trichuris muris (T. muris) is a murine gut-dwelling nematode that is the direct model for human T. trichiura, one of the major soil-transmitted helminth infections of humans. In order to assess whether chronic infection with T. muris does indeed influence the development of cancer hallmarks, both wild type mice and colon cancer model (APC ^min/+) mice were infected with this parasite. Parasite infection in wild type mice led to the development of neoplastic change similar to that seen in mice that had been treated with the carcinogen azoxymethane. Additionally, both chronic and acute infection in the APC^min/+ mice led to an enhanced tumour development that was distinct to the site of infection suggesting systemic control. By blocking the parasite induced T regulatory response in these mice, the increase in the number of tumours following infection was abrogated. Thus T. muris infection alone causes an increase in gut pathologies that are known to be markers of cancer but also increases the incidence of tumour formation in a colon cancer model. The influence of parasitic worm infection on the development of cancer may therefore be significant.

It is estimated that now 2 billion people currently live with chronic parasitic worm infections. As the incidences of cancer increase worldwide, the importance of these chronic inflammatory conditions on the development of cancer becomes more important. Several bacterial, viral and parasitic infections are already known to influence cancer development but as colon cancer is particularly prevalent worldwide, we wanted to assess the effect of a large intestinal dwelling worm, Trichuris muris (T. muris) on its aetiology. This whipworm is a natural infection of mice and has significant homology to human whipworm. From our studies, we showed that chronic infection alone induced changes in the caecum of the mouse that were comparable to those seen with a well-known carcinogen. In addition to this, T. muris infection was also able to increase the development of adenomas in the small intestine of mutant mice that spontaneously develop tumours. This change was abrogated if a T regulatory cell type was blocked during infection. The T regulatory cell type that arises during infection has been shown to play an important role in protecting the host from damage caused by the parasite and the immune response to it. The present study using the mouse model however, suggests that regulatory T cells can have negative effects, at least in terms of the development of bowel cancer. As so many people live with chronic, regulated parasitic infections, the importance of the parasites in cancer development may therefore be significant.

The distribution of human rectal aberrant crypt foci and criteria for defining the counting area

Aberrant crypt foci (ACF) are considered as a useful surrogate biomarker for colorectal cancer, although their biological significance still remains controversial. We conducted this study to clarify whether differences in the ACF counting area might have led to the discrepancies in the ACF counts among previous reports. A endoscopist proficient in ACF counting performed high-magnification chromoscopic colonoscopy in 45 subjects and investigated the distribution of ACF in four bowel segments (middle Houston valve to the dentate line and distal rectum 0-5, 5-10 and 10-15 cm). We also investigated whether the patient physique might affect the distance from the middle Houston valve to the dentate line. The prevalence of ACF was 84% and most of the ACF (170/210, 81%) were located in the bowel segment from the middle Houston valve to the dentate line. The number of ACF was significantly correlated with the bowel segment in which the counting was performed: Dentate line to the middle Houston valve and distal rectum within 0-15 cm (r=0.94, P<0.001). The patient physique did not affect the distance from the middle Houston valve to the dentate line. In conclusion, the definition of the ACF counting area may not affect the results of ACF counting.

The Essential Medicinal Chemistry of Curcumin

Curcumin is a constituent (up to ∼5%) of the traditional medicine known as turmeric. Interest in the therapeutic use of turmeric and the relative ease of isolation of curcuminoids has led to their extensive investigation. Curcumin has recently been classified as both a PAINS (pan-assay interference compounds) and an IMPS (invalid metabolic panaceas) candidate. The likely false activity of curcumin in vitro and in vivo has resulted in >120 clinical trials of curcuminoids against several diseases. No double-blinded, placebo controlled clinical trial of curcumin has been successful. This manuscript reviews the essential medicinal chemistry of curcumin and provides evidence that curcumin is an unstable, reactive, nonbioavailable compound and, therefore, a highly improbable lead. On the basis of this in-depth evaluation, potential new directions for research on curcuminoids are discussed.

Chromoendoscopy with a Standard-Resolution Colonoscope for Evaluation of Rectal Aberrant Crypt Foci

Colorectal cancer (CRC) is the second most common cause of death worldwide. According to the theory by Vogelstein, colorectal carcinogenesis involves a series of successive changes in the normal colonic mucosa, starting with excessive proliferation and focal disorders of intestinal crypts, followed by adenoma and its subsequent malignant transformation. The first identifiable changes in CRC carcinogenesis are aberrant crypt foci (ACF). ACF are invisible during routine colonoscopy yet are well identifiable in chromoendoscopy using methylene blue or indigo carmine. High-resolution colonoscopes are used for assessment of ACF. The aim of the present study was to evaluate the usefulness of standard-resolution colonoscopy for identification of rectal ACF. The following parameters were evaluated: duration of chromoendoscopy of a given rectal segment, type of ACF, sensitivity and specificity of endoscopy combined with histopathological evaluation. The mean duration of colonoscopy and chromoendoscopy was 26.8 min. In the study population, typical ACF were found in 73 patients (p = 0.489), hyperplastic ACF in 49 (p = 0.328), and dysplastic ACF in 16 patients (p = 0.107). Mixed ACF were observed in 11 individuals (p = 0.073). The sensitivity of the method was found to be 0.96 whereas its specificity 0.99. Identification of rectal ACF using standard-resolution colonoscopy combined with rectal mucosa staining with 0.25% methylene blue is characterised by high sensitivity and specificity.

New technologies and techniques to improve adenoma detection in colonoscopy

Adenoma detection rate (ADR) is a key component of colonoscopy quality assessment, with a direct link between itself and future mortality from colorectal cancer. There are a number of potential factors, both modifiable and non-modifiable that can impact upon ADR. As methods, understanding and technologies advance, so should our ability to improve ADRs, and thus, reduce colorectal cancer mortality. This article will review new technologies and techniques that improve ADR, both in terms of the endoscopes themselves and adjuncts to current systems. In particular it focuses on effective techniques and behaviours, developments in image enhancement, advancement in endoscope design and developments in accessories that may improve ADR. It also highlights the key role that continued medical education plays in improving the quality of colonoscopy and thus ADR. The review aims to present a balanced summary of the evidence currently available and does not propose to serve as a guideline.

B-RAF mutation and accumulated gene methylation in aberrant crypt foci (ACF), sessile serrated adenoma/polyp (SSA/P) and cancer in SSA/P

Background:

Sessile serrated adenomas/polyps (SSA/Ps) are a putative precursor of colon cancer with microsatellite instability (MSI). However, the developmental mechanism of SSA/P remains unknown. We performed genetic analysis and genome-wide DNA methylation analysis in aberrant crypt foci (ACF), SSA/P, and cancer in SSA/P specimens to show a close association between ACF and the SSA/P-cancer sequence. We also evaluated the prevalence and number of ACF in SSA/P patients.

Methods:

ACF in the right-side colon were observed in 36 patients with SSA/Ps alone, 2 with cancers in SSA/P, and 20 normal subjects and biopsied under magnifying endoscopy. B-RAF mutation and MSI were analysed by PCR–restriction fragment length polymorphism (RFLP) and PCR–SSCP, respectively, in 15 ACF, 20 SSA/P, and 2 cancer specimens. DNA methylation array analysis of seven ACF, seven SSA/P, and two cancer in SSA/P specimens was performed using the microarray-based integrated analysis of methylation by isochizomers (MIAMI) method.

Results:

B-RAF mutations were frequently detected in ACF, SSA/P, and cancer in SSA/P tissues. The number of methylated genes increased significantly in the order of ACF<SSA/P<cancer. The most commonly methylated genes in SSA/P were PQLC1, HDHD3, RASL10B, FLI1, GJA3, and SLC26A2. Some of these genes were methylated in ACF, whereas all genes were methylated in cancers. Immunohistochemistry revealed their silenced expression. Microsatellite instability and MLH1 methylation were observed only in cancer. The prevalence and number of ACF were significantly higher in SSA/P patients than in normal subjects. A significant correlation was seen between the numbers of SSA/P and ACF in SSA/P patients.

Conclusions:

Our results suggest that ACF are precursor lesions of the SSA/P-cancer sequence in patients with SSA/P, where ACF arise by B-RAF mutation and methylation of some of the six identified genes and develop into SSA/Ps through accumulated methylation of these genes.

Predictive value of rectal aberrant crypt foci for intraepithelial neoplasia in ulcerative colitis - a cross-sectional study

BACKGROUND

Ulcerative colitis (UC) is associated with an increased risk of colorectal cancer (CRC). Aberrant crypt foci (ACF) are important biomarkers of sporadic CRC risk. Their correlation with the risk of intraepithelial neoplasia (IN) in UC remains unclear.

AIMS

To assess whether ACF are a risk factor for IN in long-standing UC and to investigate any correlation between the clinico-epidemiological characteristics and prevalence/number of ACF in these patients.

METHODS

Seventy-six patients with long-standing UC were prospectively screened by colonoscopy with chromoendoscopy-guided endomicroscopy. ACF were sought in the lower rectum.

RESULTS

Eight INs were detected in seven (9.2%) patients. The ACF prevalence and mean number were 60.5% and 2.4 ± 2.8, respectively. The number of ACF was independently associated with the risk of having IN (odds ratio = 1.338; 95% confidence interval 1.030-1.738). ACF number revealed a good calibration (area under the receiver operating characteristic curve = 0.829) and discriminative ability (p = 0.205, Hosmer-Lemeshow test) for the prediction of synchronous IN. Patients with ≥3 ACF have a significantly higher prevalence of IN than patients with <3 ACF (22.6% vs. 0%, p = 0.001). Using this cut-off value, the performance of ACF in predicting the presence of IN was as follows: sensitivity = 100%, specificity = 65.2%, positive predictive value = 22.6%, and negative predictive value = 100%. Age >40 years, family history of CRC, and increased body mass index (BMI) were associated with a significantly higher number of ACF.

CONCLUSION

Long-standing UC patients with ≥3 ACF have a significantly higher likelihood of having IN. Age >40 years, family history of CRC, and increased BMI have significant positive associations with the number of ACF.

Accumulation of aberrant DNA methylation during colorectal cancer development

Despite the recent advances in the therapeutic modalities, colorectal cancer (CRC) remains to be one of the most common causes of cancer-related death. CRC arises through accumulation of multiple genetic and epigenetic alterations that transform normal colonic epithelium into adenocarcinomas. Among crucial roles of epigenetic alterations, gene silencing by aberrant DNA methylation of promoter regions is one of the most important epigenetic mechanisms. Recent comprehensive methylation analyses on genome-wide scale revealed that sporadic CRC can be classified into distinct epigenotypes. Each epigenotype cooperates with specific genetic alterations, suggesting that they represent different molecular carcinogenic pathways. Precursor lesions of CRC, such as conventional and serrated adenomas, already show similar methylation accumulation to CRC, and can therefore be classified into those epigenotypes of CRC. In addition, specific DNA methylation already occurs in the normal colonic mucosa, which might be utilized for prediction of the personal CRC risk. DNA methylation is suggested to occur at an earlier stage than carcinoma formation, and may predict the molecular basis for future development of CRC. Here, we review DNA methylation and CRC classification, and discuss the possible clinical usefulness of DNA methylation as biomarkers for the diagnosis, prediction of the prognosis and the response to therapy of CRC.

Suppressive effect of RAS inhibitor manumycin A on aberrant crypt foci formation in the azoxymethane-induced rat colorectal carcinogenesis model

BACKGROUND AND AIM

The chemopreventive effect of RAS inhibitors on colorectal cancer is unknown. Because aberrant crypt foci (ACF), earliest preneoplastic lesions, are highly positive for K-RAS mutation, RAS inhibitors are likely to be effective for chemoprevention. Therefore, in the present study, the suppressive effect of a RAS inhibitor, manumycin A, on ACF formation in an azoxymethane (AOM)-induced rat colorectal carcinogenesis model was investigated.

METHODS

Rats injected with AOM were administered manumycin A (30 mg/kg) subcutaneously thrice weekly for 8 weeks or for 4 weeks (latter half), sacrificed at 8 weeks, and examined for ACF in the colorectum. Phosphorylated ERK and Ki-67 expression was evaluated by immunohistochemistry. Apoptosis was assessed by TUNEL staining.

RESULTS

The mean number of ACF in the 8-week manumycin A group (72.9 ± 20.1) was significantly lower than in the vehicle group (155.6 ± 56.7, P < 0.01), and it was significantly lower even in the 4-week manumycin A group than in the vehicle group (92.2 ± 13.0 vs 222.3 ± 83.3, P < 0.01). The positive rate for phosphorylated ERK in the manumycin A group (13.5 ± 19.2%) was significantly lower than in the vehicle group (50.2 ± 19.8%, P < 0.01). The positive rate for Ki-67 in the manumycin A group (2.2 ± 3.4%) was significantly lower than in the vehicle group (14.7 ± 8.2%, P < 0.01). There were significantly more terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells in tissue samples from the manumycin A group versus the vehicle group (8.6 ± 9.7% vs 2.9 ± 2.0%, P < 0.05).

CONCLUSION

Manumycin A suppressed ACF formation in the AOM-induced colorectal carcinogenesis model, demonstrating that RAS inhibitors may be very effective for chemoprevention of colorectal cancers.

Chromocolonoscopy

Chromocolonoscopy is the process of endoscopically examining the colon mucosa after it has been stained with dye. The goal is to allow the endoscopist to identify subtle features in the mucosa, such as morphologically flat polyps or crypt patterns. Studies examining the efficacy of chromocolonoscopy to identify adenomas missed by conventional colonoscopy have shown that although chromocolonoscopy increases polyp yield, most additional lesions are small in size. Staining can also help in differentiating neoplastic from non-neoplastic polyps. Perhaps the most useful aspect of chromocolonoscopy is increasing the yield for dysplasia in patients undergoing colonoscopy for inflammatory bowel disease surveillance.

Relationship of human rectal aberrant crypt foci and formation of colorectal polyp: One-year following up after polypectomy

AIM: To clarify the relationship of human rectal aberrant crypt foci and formation of colorectal polyp.

METHODS: Eighty-nine subjects were recruited from the population of Japanese individuals who underwent polypectomy at Yokohama City University Hospital. All patients had baseline adenomas removed at year 0 colonoscopy. Aberrant crypt foci (ACF) were defined as lesions in which the crypts were more darkly stained with methylene blue than normal crypts and had larger diameters, often with oval or slit-like lumens and a thicker epithelial lining.

RESULTS: A total of 366 ACFs were identified in 89 patients; all had baseline adenomas removed at the first examination (year 0) colonoscopy and returned for the second (year 1). ACF in the lower rectum were assessed at year 0 and study group were divided into two groups depend on ACF numbers, 0-3 or over 3. All participants were examined in the number and maximum size of adenoma. There was no statistical difference in number and maximum size of ACF at year 0, however, maximum size of adenoma was larger in over 3 group than 0-3 group at year 1.

CONCLUSION: The number of ACF may be a predictive factor of relatively large adenoma incidence in the pilot phase study.

Probe-based confocal laser endomicroscopy evaluation of colon preneoplastic lesions, with particular attention to the aberrant crypt foci, and comparative assessment with histological features obtained by conventional endoscopy

The colorectal carcinoma represents one of the most common and aggressive malignancies, still characterized by an unacceptable mortality rate, mainly due to the high metastatic potential and to a late diagnosis. In the last years, the research community focused on the chance of improving the endoscopic screening to detect neoplastic lesions in a very early stage. Several studies proposed aberrant colonic crypt foci as the earliest recognizable step of transformation in colonic multiphase carcinogenesis. We previously demonstrated the clinical applicability and predictive power of probe-based confocal laser endoscopy (pCLE) in superficial colorectal neoplastic lesions and also characterized in vivo a case of dysplasia-associated lesional mass (DALM) in ulcerative colitis. Now, we aim to evaluate the accuracy of pCLE in the detection of ACF comparing in double-blind manner the microendoscopic and histopathological features resulting from colonic biopsy. By pCLE, we identified specific crypt architecture modifications associated with changes in cellular infiltration and vessels architecture, highlighting a good correspondence between pCLE features and histology.

Biology and diagnosis of aberrant crypt foci

AIM

Aberrant crypt foci (ACFs) are clusters of colonic crypts that can be identified after staining and that have a different behaviour than the surrounding crypts. They have been hypothesized to be the potential precursors of colonic neoplastic lesions. Since they are detectable in vivo with endoscopic stains, they have been proposed as early biomarkers for colonic carcinogenesis. Our aim was to examine the literature regarding the role of ACFs in the pathogenesis of colorectal cancer (CRC).

METHOD

An intensive PubMed search was performed with the following terms: aberrant crypt foci, colorectal cancer, biomarker, carcinogenesis.

RESULTS

  Aberrant crypt foci have a variable prevalence and little is known about their natural history. They can be classified as hyperplastic or dysplastic. There is evidence that supports their role as preneoplastic lesions and features detectable by chromoendoscopy have been related to CRC risk. Moreover, ACFs have been shown to harbour genetic and epigenetic alterations common in adenomas and CRC. However, contradictory results have been obtained and difficulties in endoscopic detection and characterization have been described in large-scale studies.

CONCLUSION

  Despite the inconsistencies in ACF detection and characterization, several genetic and epigenetic changes common in both ACFs and CRC have been verified throughout the studies. This evidence is increasingly strong and it grows along with progress in the knowledge of carcinogenesis molecular pathways. Clinical application of ACFs as an intermediate endpoint for colorectal carcinogenesis is under development and a deeper knowledge of cancer mechanisms is needed before it can be applied or discarded.

Aberrant crypt foci as predictors of colorectal neoplasia on repeat colonoscopy

OBJECTIVE

To estimate the risk for colorectal neoplasia detected on repeat colonoscopy in relation to aberrant crypt foci (ACF) frequency reported during the previous baseline examination.

METHODS

From July 2003 until December 2008, patients had a colonoscopy with an ACF study using a magnifying colonoscope. The distal 20 cm section of colon was sprayed with Methylene Blue to ascertain the ACF frequency, the independent variable. Patients were categorized into low and high ACF count using the median as the cut point. Data collected from consenting patients included age, gender, height, weight, ethnicity, smoking history, family history of colorectal cancer (CRC), and personal history of colorectal neoplasia. A follow-up colonoscopy was performed at an interval as dictated by clinical surveillance guidelines. The main outcome was surveillance detected advanced colorectal neoplasia (SDAN) detected on repeat colonoscopy. Logistic Regression was used to calculate risk of SDAN on repeat colonoscopy in relation to baseline ACF count.

RESULTS

74 patients had a baseline ACF exam and a repeat surveillance colonoscopy. The median ACF was six and thus a high ACF count was >6 ACF and a low ACF count was ≤6 ACF. Patients diagnosed with SDAN were more likely to have had a high ACF number at baseline compared to patients without these lesions at follow-up (adjusted odds ratio = 12.27; 95% confidence interval: 2.00-75.25) controlling for age, sex, smoking, history of prior adenoma, family history of colon cancer, obesity, and time interval to surveillance exam. A sub analysis of our results demonstrated that this relationship was observed in 48 patients who were undergoing a surveillance colonoscopy for a previous adenoma and not those receiving surveillance for a family history of neoplasia.

CONCLUSIONS

Increased number of ACF in the distal colorectum was independently associated with substantial risk for future advanced neoplasia. This relationship was observed in patients undergoing surveillance for previous adenomas. Thus, ACF may serve as potential biomarkers in patients with adenomas to help identify patients who may need additional surveillance.

Investigation of the prevalence and number of aberrant crypt foci associated with human colorectal neoplasm

BACKGROUND

Aberrant crypt foci (ACF) are considered to be useful as surrogate biomarker for colorectal cancer (CRC), but the biological significance of ACF remains controversial. We attempted to investigate the relationship between the presence of ACF and human colorectal carcinogenesis using a relatively large sample size.

METHODS

We carried out high-magnification chromoscopic colonoscopy to identify ACFs in 861 subjects undergoing a diagnostic endoscopy at the Yokohama City University Hospital. The present study compared the prevalence and number of ACFs in three subject groups (normal subjects, adenoma cases, and CRC cases). The correlations between the demographic and behavioral characteristics of the subjects and the prevalence of ACFs were also assessed.

RESULTS

The prevalence of ACF was 64%, 88%, and 95%, and the mean number of ACF was 3.6, 6.2, and 10.1, in normal subjects, adenoma cases, and CRC cases, respectively. When differences in the prevalence and number of ACFs among age- and sex-stratified subject groups were examined, significant stepwise increments from normal subjects to adenoma cases to CRC cases were apparent (P < 0.001). Moreover, an age- and sex-adjusted multiple logistic regression analysis revealed that smoking and alcohol habits had a synergistic effect, increasing the prevalence of ACFs as well as the risk of CRC (P < 0.001).

CONCLUSIONS

These results suggested that ACF may serve as a reliable surrogate biomarker for human colorectal carcinogenesis.

IMPACT

The use of ACF as an endpoint may enable the size, duration, and cost of CRC chemoprevention studies to be reduced.

Randomized double-blind trial of sulindac and etodolac to eradicate aberrant crypt foci and to prevent sporadic colorectal polyps

PURPOSE

On the basis of the results of our preliminary trial suggesting that aberrant crypt foci (ACF) could be eradicated by short-term administration of sulindac, in the present study, we explored the feasibility of using ACF as surrogate markers for chemoprevention of colorectal cancer.

EXPERIMENTAL DESIGN

Randomly assigned to sulindac (300 mg daily), etodolac (400 mg daily), and placebo groups were 189 subjects without polyps or who had undergone polypectomy. Drugs were administered for 2 months. ACF in the rectal region were counted by magnifying endoscopy. Occurrence of polyps was evaluated at 12 months. A planned interim analysis was conducted.

RESULTS

ACF number at 2 months was significantly suppressed in the sulindac group (P = 0.0075), but not in the etodolac group (P = 0.73). In the sulindac group, the numbers of adenomas plus hyperplastic polyps (total polyps) and adenomas at 12 months were significantly (P = 0.02) and marginally (P = 0.064) lower, respectively, in comparison with the placebo group; no such difference was observed in the etodolac group. In analysis of only polypectomized subjects, the numbers of total polyps and adenomas in the sulindac group were even more markedly lower, with P values of 0.014 and 0.034, respectively. A similar tendency was confirmed by analyses of the incidence of polyps at 12 months. Suppression rates of total polyps and adenomas in ACF responders to sulindac were significantly greater than in nonresponders. In all groups, compliance was more than 90% and no intolerable adverse effects were observed.

CONCLUSIONS

ACF may be useful as surrogate lesions for chemoprevention of colorectal cancer.

Randomized phase II trial of sulindac, atorvastatin, and prebiotic dietary fiber for colorectal cancer chemoprevention

Sulindac, atorvastatin, or prebiotic dietary fiber may reduce colorectal cancer (CRC) risk. However, clinical trial data are currently limited. We conducted a randomized, phase II chemoprevention trial involving subjects 40 years or older, with previously resected colon cancer or multiple/advanced colorectal adenomas. Magnification chromoendoscopy (MCE) was performed to identify and characterize rectal aberrant crypt foci (ACF); eligibility criteria required five or more rectal ACFs at baseline. Intervention assignments were as follows: (a) atorvastatin 20 mg qd; (b) sulindac 150 mg bid; (c) oligofructose-enriched inulin (as ORAFTI®Synergy1) 6 gm bid; or (d) control (maltodextrin) 6 gm bid, for 6 months. Percent change in rectal ACF number (%ΔACF) within arm was the primary endpoint. Secondary endpoints included changes in proliferation (Ki67) and apoptosis (caspase-3), as measured from normal mucosa biopsy samples. Among 85 eligible randomized subjects, 76 (86%) completed the trial per protocol. The median (range) of rectal ACF was 9 (5-34) and 8 (0-37) at baseline and postintervention, respectively. The median (SD) for %ΔACF was 5.6 (-69% to 143%), -18.6 (-83% to 160%), -3.6 (-88% to 83%), and -10.0 (-100% to 117%) in the atorvastatin, sulindac, ORAFTI®Synergy1 and control arms, respectively. Neither within-arm (P = 0.12-0.59) nor between-arm (P = 0.30-0.92) comparisons of %ΔACF were statistically significant. The active and control interventions also seemed to have similar effects on mucosal proliferation and apoptosis (P > 0.05 for each comparison). Data from this multicenter, phase II trial do not provide convincing evidence of CRC risk reduction from 6-month interventions with atorvastatin, sulindac, or ORAFTI®Synergy1, although statistical power was limited by the relatively small sample size.

Aberrant crypt foci: the case for inclusion as a biomarker for colon cancer

Aberrant crypt foci (ACF) are one of the earliest histopathological manifestations of colon cancer. In this review, we critically present the molecular, cellular, histopathological, and chemopreventive evidence that ACF are relevant biomarkers for colon cancer. The laboratory and clinical evidence are highly suggestive that ACF are in the pathway leading to colon cancer, but not all ACF will do so. The possible fate and outcome of ACF in the progression toward colon cancer may be dependent on a number of features that define their predictive power for the prevention or progression of cancer.

Increased frequency of serrated aberrant crypt foci among smokers

OBJECTIVES

The American College of Gastroenterology has published guidelines recently that suggest that smokers with a history of >20 pack years may need screening for colorectal cancer (CRC) at an earlier age than non-smokers. Aberrant crypt foci (ACF) may represent important precursors for colorectal neoplasms and potential surrogate biomarkers. Clarifying the role of ACF in relation to known CRC risk factors such as smoking may have important implications for screening as well as our understanding of tobacco use and colorectal carcinogenesis. Our goal was to examine whether smoking at least 20 pack years was associated with an increased frequency of ACF.

METHODS

We gathered detailed smoking history, personal and family history of CRC, and other epidemiologic data (age, gender, height, weight, ethnicity, and medication use) from 125 patients undergoing routine screening or surveillance colonoscopy. We used a magnifying colonoscope (Olympus Close Focus Colonoscope XCF-Q160ALE, Olympus Corporation, Tokyo, Japan) and examined the distal 20 cm section of colon after staining with 0.5% methylene blue. ACF were counted and characterized histologically. Hyperplastic ACF were further characterized as either serrated or non-serrated.

RESULTS

Smoking at least 20 pack years was associated with an increased likelihood (adjusted odds ratio (OR)=3.45; 95% confidence interval (CI)=1.93-6.18) of having more than the median number of ACF (> or = 15) compared with non-smokers. Similarly, patients with a personal history of advanced neoplasia were more likely (adjusted OR=3.42; 95% CI=1.01-11.67) to have a greater than median number of ACF compared with patients without this diagnosis. Smokers were more likely than non-smokers to have serrated ACF (P=0.002).

CONCLUSIONS

Smoking at least 20 pack years seems to be associated with increased number of ACF in the rectum and distal sigmoid, especially those with serrated histology. Our data support ACG guidelines for earlier screening for CRC among smokers and add to our understanding of how colorectal carcinogenesis is related to tobacco use.

Variational image segmentation for endoscopic human colonic aberrant crypt foci

The aim of this paper is to introduce a variational image segmentation method for assessing the aberrant crypt foci (ACF) in the human colon captured in vivo by endoscopy. ACF are thought to be precursors for colorectal cancer, and therefore their early detection may play an important clinical role. We enhance the active contours without edges model of Chan and Vese to account for the ACF's particular structure. We employ level sets to represent the segmentation boundaries and discretize in space by finite elements and in (artificial) time by finite differences. The approach is able to identify the ACF, their boundaries, and some of the internal crypts' orifices.

Reliability and accuracy of the endoscopic appearance in the identification of aberrant crypt foci

BACKGROUND

Aberrant crypt foci (ACF) have emerged as a putative precursor to colorectal adenoma, with potential use as a biomarker of colorectal cancer. However, there are wide differences in ACF prevalence, dysplasia, and histologic confirmation rates across studies. These differences may, in part, be because of variability in identification of endoscopic criteria.

OBJECTIVE

To systematically evaluate the accuracy and reliability of various endoscopic criteria used to identify ACF when using magnification chromoendoscopy (MCE).

DESIGN

Images obtained via MCE were shown to participating endoscopists who diagnosed them as ACF or not and who assessed them for the endoscopic characteristics used to identify ACF in the literature.

MAIN OUTCOME MEASUREMENTS

The predictive ability of the endoscopic criteria (crypt number, staining, margin, crypt size, epithelial thickness, and lumen shape) for histologic confirmation of ACF, and their reliability across endoscopists. The accuracy of the examiners in identifying ACF that were histologically confirmed was also assessed.

RESULTS

The interrater agreement rate for all except one of the endoscopic criteria (crypt number) was low and did not improve with training. None of the criteria could significantly predict histologic confirmation of ACF. Despite training exercises, accuracy of endoscopists to correctly identify a histologically proven ACF remained low.

LIMITATIONS

Still images with x40 optical magnification were analyzed rather than real-time endoscopy. All ACF samples were hyperplastic; none were dysplastic.

CONCLUSIONS

No endoscopic criteria evaluated by our study predicted histologic confirmation of ACF. MCE had low accuracy and poor reliability.

Flat lesions in CT colonography

Flat lesions have been a source of controversy because of concerns that CT colonography (CTC) is insensitive in detecting these lesions, yet they may harbor a high incidence of advanced neoplasia. The wide variation in the reported incidence of flat lesions may in part be due to the lack of a uniform definition of "flat", and in fact in many prior reports the inclusion criteria for flat are not even clearly specified. Emphasis on the more recent CTC literature suggests that when limited the target lesion to neoplasia (adenomas or adenocarcinoma), the incidence of flat lesions is low and most can be detected by CTC. Using fecal tagging and careful attention to the proper methods of searching for flat lesions with both 3D and 2D techniques can maximize the detection of flat lesions at CTC. Computer-aided detection may be helpful.

A multicenter study of prevalence and risk factors for aberrant crypt foci

BACKGROUND & AIMS

Aberrant crypt foci (ACF) are the putative precursor of colorectal adenomas. However, there are limited data available on the prevalence and risk factors for ACF.

METHODS

Subjects from the Prostate, Lung, Colorectal and Ovarian cancer screening trial were recruited for an ACF study, with subjects with adenoma history being oversampled. By using a standardized protocol of magnified chromoendoscopy with methylene blue staining (up to the middle rectal fold), ACF were photo-documented and removed for histologic evaluation.

RESULTS

A total of 505 (66% male; 55% > or =70 y) subjects from 4 institutions were examined; 42% had no adenoma, 32% had nonadvanced distal adenoma, and 25% had advanced distal adenoma at the baseline Prostate, Lung, Colorectal and Ovarian cancer screening trial examination (8.2 years before ACF examination on average). A total of 68% of this population had 1 or more ACF, 43% had 1 to 3, 19% had 4 to 6, and 5% had 7 or more. Baseline adenoma status was not associated with ACF prevalence (range, 66%-69%) or mean number of ACF (range, 3.1-3.5). Of 143 endoscopic ACF examined histologically, 68.5% were confirmed to be ACF. In a logistic model, current (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2-5.6) and former smoking (OR, 1.6; 95% CI, 1.1-2.5) were associated with higher ACF prevalence; a body mass index greater than 30 was associated with lower prevalence (OR, 0.53; 95% CI, 0.35-0.8). Age, sex, family history of colorectal cancer, and aspirin/nonsteroidal anti-inflammatory drug use were not associated significantly with ACF prevalence.

CONCLUSIONS

ACF prevalence and number were not associated with adenoma history, and only 68.5% of endoscopic ACF were confirmed histologically. These results raise concern about the use of ACF as a surrogate marker of colorectal cancer risk.

Aberrant crypt foci: endoscopic assessment and cell kinetics characterization

BACKGROUND AND AIMS

Aberrant crypt foci (ACF) are preneoplastic lesions in animal models of colorectal cancer. The aim of the study is to investigate if ACF are involved in human colorectal carcinogenic process and if they can be helpful in predicting the presence of a colorectal neoplasia.

METHODS

The study included, between 2003 and 2005, 182 patients, 62 with adenoma, 55 with colorectal carcinoma, 53 without colorectal lesions, and 12 with nonneoplastic mucosal polyps. The number of rectal ACF was determined by colonoscopy. Proliferation and apoptosis indexes were evaluated by immunohistochemistry in rectal ACF, in normal rectal mucosa, and in carcinomatous tissue.

RESULTS

The mean number of rectal ACF in patients with rectal neoplasia was 12.64, significantly higher than in patients with neoplastic lesions elsewhere in the colon (p=0.01). The apoptosis index in ACF of patients with colorectal carcinoma or adenoma aged 50 years or older was significantly lower than in younger patients (1.3% vs 2.7%, p=0.01) and, in patients with carcinoma, lower than in normal mucosa (1.1% vs 2.1%, p=0.002). The proliferation index was significantly higher in ACF of patients with colorectal neoplasia aged less than 50 years than in normal mucosa (10.9% vs 7.7%, p=0.02). The apoptosis index in ACF foci of patients with carcinoma (1.1%) was significantly lower than in patients without lesions (2.2%) and than in normal mucosa (2%). The mean number of ACF is significantly higher in patients with polyps larger than 1 cm (11.28 vs 6.27, p=0.02).

CONCLUSION

Aberrant crypt foci probably precede the appearance of neoplasia and may be helpful in predicting the presence of a colorectal neoplastic lesion.

Aberrant crypt foci in colon cancer epidemiology

Colonic carcinogenesis is characterized by progressive accumulations of genetic and epigenetic derangements. These molecular events are accompanied by histological changes that progress from mild cryptal architectural abnormalities in small adenomas to eventual invasive cancers. The transition steps from normal colonic epithelium to small adenomas are little understood. In experimental models of colonic carcinogenesis aberrant crypt foci (ACF), collections of abnormal appearing colonic crypts, are the earliest detectable abnormality and precede adenomas. Whether in fact ACF are precursors of colon cancer, however, remains controversial. Recent advances in magnification chromoendoscopy now allow these lesions to be identified in vivo and their natural history ascertained. While increasing lines of evidence suggest that dysplastic ACF harbor a malignant potential, there are few prospective studies to confirm causal relationships and supporting epidemiological studies are scarce. It would be very useful, for example, to clarify the relationship of ACF incidence to established risks for colon cancer, including age, smoking, sedentary lifestyle, and Western diets. In experimental animal models, carcinogens dose-dependently increase ACF, whereas most chemopreventive agents reduce ACF incidence or growth. In humans, however, few agents have been validated to be chemopreventive of colon cancer. It remains unproven, therefore, whether human ACF could be used as reliable surrogate markers of efficacy of chemopreventive agents. If these lesions could be used as reliable biomarkers of colon cancer risk and their reductions as predictors of effective chemopreventive agents, metrics to quantify ACF could greatly facilitate the study of colonic carcinogenesis and chemoprevention.

Aberrant crypt foci: are they intermediate endpoints of colon carcinogenesis in humans?

PURPOSE OF REVIEW

There is a wealth of literature, both from epidemiological and molecular studies, which support the role of aberrant crypt foci (ACF) as a putative precursor to colorectal adenomas and a potential biomarker for colorectal carcinoma. In this review, we critically examine the evidence on employing ACF as an intermediate endpoint.

RECENT FINDINGS

Recent, larger-scale, multicenter studies of ACF have raised questions about ACF. The prevalence of ACF has not correlated with colorectal adenomas, and the technique for ACF detection using high-magnification chromoendoscopy has demonstrated considerable variability across endoscopists and over time. Dysplastic ACF, once postulated as the ACF destined for adenomatous transformation, have been rarely identified in US individuals, in contrast to European and Japanese investigations. A substantial percentage of purported, endoscopically detected ACF have not been confirmed on histologic review. Finally, molecular characterization of ACF has been studied on only a limited basis.

SUMMARY

ACF remain a potential biomarker for colorectal cancer, but similar to other biomarkers under development, additional study of ACF is needed before reliable, clinical application can be assured.

Aberrant crypt focus size predicts distal polyp histopathology

Aberrant crypt foci (ACF) are the earliest histopathologic lesion associated with colorectal cancer. ACFs are commonly used as a surrogate marker for colorectal cancer chemoprevention studies in rodents and, more recently, in humans. However, ACF prevalence in unselected populations is not known, nor which ACF features are important for predicting polyp histopathology. To address these questions, we did magnification chromo-colonoscopy on all patients undergoing routine colorectal cancer screening over a 31-month period. ACFs were classified by location, size (small, <20 crypts/ACF; medium, 20-100 crypts/ACF; large, >100 crypts/ACF), and whether they were elevated above the tissue plane. Overall, 802 magnification chromo-colonoscopies with ACF enumeration were done. Mean patient age was 58.6 +/- 8.5 years, of whom 56% were female, 58% were African American, 21% were Caucasian, and 16% were Latino. Total ACF number, along with increasing ACF size and elevation, correlated with the presence of distal hyperplastic polyps and were higher in African Americans. In contrast, ever-smaller ACFs correlated with the presence of distal adenomas and were independent of age and race. The odds ratio for patients with >or=6 small ACFs and adenomas was 6.02 (95% confidence interval, 2.64-13.70) compared with patients with <or=5 small ACFs, whereas the odds ratio for patients with >or=1 large ACF and hyperplastic polyps was 5.88 (95% confidence interval, 3.00-11.67) compared with patients with none. Small flat ACFs correlate with the presence of distal adenomas, whereas large raised ACFs correlate with the presence of hyperplastic polyps.

Abberant crypt foci -- importance in colorectal carcinogenesis and expression of p53 and mdm2: a changing concept

BACKGROUND

The presence of aberrant crypt foci (ACF) represents an important preneoplastic condition of the large intestine. The ACF are used extensively as the biological end point to study the effects of diet, biological agents and chemotherapeutic agents as they undergo distinct morphological and genetic changes in response to these factors. Till date, in human ACF, K-ras, beta-catenin, carcinoembryonic antigen (CEA) and adenomatous polyposis coli (APC) protein expression have been investigated, but the expression of late markers of colon carcinogenesis have not been studied in great detail.

AIMS

To study the significance of ACF in carcinogenesis, the incidence of ACF in colorectal carcinoma (CRC) patients and the expression profiles of the tumor repressor protein p53 and the murine double minute (mdm2) protein in ACF.

METHODS AND MATERIALS

The pattern of expression, histology and immunohistochemistry of the p53 and mdm2 proteins were studied in 32 colectomy specimens. Careful scoring was carried out using standard criteria. The prevalence of ACF, types of ACF, surrounding mucosal changes and the relation of ACF with tumor morphology and aggressiveness were determined, as was any difference in the staining pattern between hyperplastic and dysplastic ACF.

RESULT

Aberrant crypt foci were present in a large number of cases (84.4%), of which 65% were hyperplastic. All hyperplastic and dysplastic ACF tested positive for p53 in the nucleus. Both the nucleus and cytoplasm tested positive for mdm2 irrespective of the degree of dysplasia. No correlation was noted between ACF and tumor histology.

CONCLUSION

The p53 and mdm2 proteins are expressed during the very early stages of mucosal changes in ACF, irrespective of histological changes, but the pattern of expression can differ depending on geographical barriers, genetic factors, diet and environmental conditions. This results suggests that the conventional adenoma-carcinoma sequence is not completely correct. The detection of ACF and p53 and mdm2 expression can help to curtail the disease in its early stage by targeted therapy.

The natural history of aberrant crypt foci

BACKGROUND

Aberrant crypt foci (ACF) are the putative precursors to colorectal adenomas and may be useful as biomarkers. Knowledge of their natural history is essential to understanding their potential utility.

OBJECTIVE

Our purpose was to examine ACF detection 1 year after initial observation.

DESIGN

We conducted a multicenter study of ACF by using a standardized protocol. ACF in the rectum were assessed and subjects returned 1 year later to evaluate the natural history of the lesions.

SETTING

Ancillary study to the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

RESULTS

Of 78 subjects enrolled, 64 (82%) returned for a repeat examination 1 year later. The mean age was 71 years, 70% were male, and 54% had a history of adenomatous polyps. At the initial examination, 66% of subjects had at least 1 ACF detected in the rectum, with a mean of 2.1 +/- 2.3 per person. One year later, 60% of these subjects had at least 1 of the original ACF reidentified, but only 43% of all ACF were reidentified. A total of 56% of subjects had new ACF identified.

LIMITATIONS

These results are generated from the pilot phase. Improvements or change in technique over time could have influenced the results.

CONCLUSIONS

A total of 60% of subjects who had ACF continued to have at least one ACF 1 year later, but less than half the specific ACF could be reidentified, and more than 50% of subjects had new ACF. These results imply a considerable dynamic to ACF detection over a 1-year period of observation.

Aberrant crypt foci as precursors of the dysplasia-carcinoma sequence in patients with ulcerative colitis

PURPOSE

Long-standing ulcerative colitis (UC) predisposes patients to the development of colorectal cancer, but surveillance of colitis-associated cancer by detecting the precancerous lesion dysplasia is often difficult because of its rare occurrence and normal-looking appearance. In sporadic colorectal cancer, aberrant crypt foci (ACF) have been reported by many investigators to be precursor lesions of the adenoma-carcinoma sequence. In the present study, we analyzed the genetic background of ACF to determine whether they could be precursors for dysplasia, and we examined the usefulness of endoscopic examination of ACF as a surrogate marker for surveillance of colitis-associated cancer.

EXPERIMENTAL DESIGN

ACF were examined in 28 UC patients (19 patients with UC alone and 9 patients with UC and dysplasia; 2 of those patients with dysplasia also had cancer) using magnifying endoscopy. K-ras, APC, and p53 mutations were analyzed by two-step PCR RFLP, in vitro--synthesized protein assay, and single-strand conformation polymorphism, respectively. Methylation of p16 was analyzed by methylation-specific PCR.

RESULTS

ACF that appeared distinct endoscopically and histologically were identified in 27 out of 28 UC patients. They were negative for K-ras, APC, and p53 mutations but were frequently positive for p16 methylation (8 of 11; 73%). In dysplasia, K-ras and APC mutations were negative but p53 mutation (3 of 5; 60%) and p16 methylation (3 of 5; 60%) were positive. There was a significant stepwise increase in the number of ACF from patients with UC alone to patients with dysplasia and to patients with cancer. Univariate and multivariate analyses showed significant correlations between ACF and dysplasia.

CONCLUSIONS

We have disclosed an ACF-dysplasia-cancer sequence in colitis-associated carcinogenesis similar to the ACF-adenoma-carcinoma sequence in sporadic colon carcinogenesis. This study suggests the use of ACF instead of dysplasia for the surveillance of colitis cancer and warrants further evaluation of ACF as a surveillance marker in large-scale studies.

Abnormal expression of M1/MUC5AC mucin in distal colon of patients with diverticulitis, ulcerative colitis and cancer

The abnormal expression of gastric M1/MUC5AC mucin in precancerous lesions and colon cancer evidenced by immunohistochemistry led us to check for its presence in the mucus obtained directly from patients undergoing surgery for cancerous (adenocarcinoma) or inflammatory (diverticulitis or ulcerative colitis) diseases. In parallel, the authors quantified aberrant crypt foci (ACF) and their immunolabelling by M1/MUC5AC in mucosae of cancer and diverticulitis patients. Immuno-Radio-Metric Assay of M1/MUC5AC mucin developed by the authors was used to detect M1/MUC5AC mucin in the colonic mucus scraped from surgical specimens. M1/MUC5AC mucin was detected in the mucus of 51/69 (74%) patients with colon adenocarcinoma, versus 7/27 (26%) patients with diverticulitis (threshold: 30 units of M1 mucin per mg protein, area under ROC curve: 0.80). M1/MUC5AC was present in significantly (p < 0.001) larger amounts in the mucus of cancer versus diverticulitis patients. All (10/10) patients with ulcerative colitis tested showed levels above the threshold and their mucosae were strongly labelled with the anti-M1/MUC5AC antibody by immunohistochemistry. Patients with cancer exhibited 3 fold more ACF than those with diverticulitis, but no significant difference was observed in the mean size and M1/MUC5AC expression pattern of ACF between these two groups. The expression of M1/MUC5AC was in correlation with their size. In macroscopically normal mucosa, ACF were the most important source of M1/MUC5AC mucin. Testing of M1/MUC5AC can enhance the detection of precancerous lesions and colon cancer.

Novel clinical in vivo roles for indigo carmine: high-magnification chromoscopic colonoscopy

Since the adenoma-carcinoma sequence was first proposed by Morson in the 1970s, it has become widely accepted that detection and subsequent removal of polypoid adenomas from the colon reduces the incidence of colorectal cancer. These adenomas are relatively easy to detect by conventional colonoscopy; however, large population studies have shown that despite resection of polypoid adenomas, interval colorectal cancers still occurred. Recent advances in technology have given today's endoscopists access to high-resolution and high-magnification scopes, which has facilitated detection of flat and depressed colorectal lesions. Current data suggest that such morphologically distinct lesions may account for up to 30% of all colorectal adenomas. Furthermore, flat and depressed lesions of the large bowel may confer greater malignant potential compared to polypoid adenomas. The majority of flat lesions show only subtle changes by conventional colonoscopy, but the use of stains, such as indigocarmine, in addition to magnification colonoscopy can enhance their detection significantly. In this paper, we discuss the rationale for detecting flat colorectal lesions. We explore the use of high-magnification colonoscopy and chromoendoscopy, with particular reference to the application of indigocarmine, in this patient group. We also discuss the novel therapeutic techniques now available for these lesions.

Epidemiology of colonic aberrant crypt foci: review and analysis of existing studies

Since first described in a rodent model in 1987, aberrant crypt foci (ACF) in the colon have been shown to exhibit many of the molecular features of the more advanced colonic neoplasms including cancer. Therefore, they may be early lesions with potential for progression, and be valuable biomarkers for reduction of risk of colorectal cancer (CRC). For this review, we searched PubMed, and reference lists of recent publications, for studies which reported on associations of features of ACF in humans, such as number or size, with subject characteristics, such as age or family history of CRC. Over 150 papers have reported on ACF in humans. However, the vast majority of these publications are concerned with molecular and morphological features of biopsied lesions, and not their epidemiology. None of the epidemiological studies were of optimum design, primarily due to their absence of a well-defined subject sampling frame or method. Given their 'first-generation' nature, consistent findings were of increased ACF number with age and with synchronous advanced colonic neoplasia. One study reported a higher mean number of ACF in subjects with a family history of CRC than in those without. The strongest evidence on the ability of ACF to predict a diagnosis of CRC will be from prospective studies with baseline ACF assessment in a large sample of disease-free persons (many thousands) who are followed carefully for many years. In the interim, because ACF are asymptomatic, well-designed cross-sectional studies are feasible and will yield valuable information on the relation of ACF to the known risk factors for CRC. This information can then be used to improve the design of prospective studies, and of clinical intervention trials that use ACF as an intermediate endpoint.

Gene expression patterns distinguish colonoscopically isolated human aberrant crypt foci from normal colonic mucosa

Aberrant crypt foci (ACF) are considered the earliest identifiable preneoplastic colonic lesions; thus, a greater understanding of the nature of genetic changes underlying the transformation of normal colonic mucosa (NM) into ACF may provide insight into the mechanisms of carcinogenesis. ACF were identified by indigo carmine spraying onto colonic mucosa during colonoscopy and isolated as standard pinch biopsies of the mucosal areas containing the ACF. RNAs isolated from ACF and matched NM biopsies from the ascending and descending colons of 13 patients were analyzed on arrays containing 9128 cDNAs. Thirty-four differentially expressed (P < 0.001) genes were found in a paired comparison of the ACF and NM samples, and 25 of 26 matched pairs of ACF and NM could be correctly classified in leave-one-out cross-validation. Differential expression for seven of eight genes was confirmed by real-time reverse transcription-PCR. Furthermore, ACF and NM samples, including six pairs of ACF and NM samples that had not previously been analyzed by array hybridization, can be correctly classified on the basis of the overexpression in ACF of three selected genes (REG4, SRPN-B5, and TRIM29) evaluated by real-time reverse transcription-PCR. In a separate analysis of 13 biopsy pairs from either ascending or descending colon, ACF and NM samples could also be correctly classified by the gene expression patterns. Analysis of gene expression differences in ACF from the ascending and descending colon versus NM samples indicates that ACF from these distinct colonic locations are converging toward similar gene expression profiles and losing differences in gene expression characteristic of NM from the ascending versus descending colon.

Detection and treatment of early flat and depressed colorectal cancer using high-magnification chromoscopic colonoscopy: a change in paradigm for Western endoscopists?

Japanese researchers reported flat and depressed colorectal lesions in the 1980s. Such lesions were thought irrelevant to Western populations and described as "Phantom" or "Akitas" carcinoma. Many depressed neoplasms arise through the de novo pathogenic sequence and demonstrate early invasive characteristics. All investigators report difficulties in identifying flat and depressed lesions using conventional colonoscopy. Failure to detect and treat such lesions may be responsible for the current shortfalls in secondary colorectal cancer prevention. Given the introduction of colorectal cancer screening programs in the United Kingdom, Europe, and the United States, it is essential to re-evaluate the significance of flat lesions as applicable to Western cohorts and explore the safety and efficacy of new endoscopic technology and interventional therapeutics.

Aberrant crypt foci: what we know and what we need to know

Aberrant crypt foci (ACF) have emerged as a putative precursor to colorectal adenomas and are a potential biomarker for colorectal carcinoma. In this review, we describe the histologic and endoscopic characteristics of human ACF, summarize the identified genetic abnormalities, and examine the evidence for using ACF as a biomarker for colorectal carcinoma. The published literature on aberrant crypt foci was identified using a MEDLINE/PubMed search with a secondary review of cited publications. Epidemiologic studies support a role for ACF in the adenoma-carcinoma sequence. Genetic abnormalities that occur in and are characteristic of colorectal carcinoma have been described in ACF. Although chromoendoscopy with magnification colonoscopy can identify human ACF in vivo, standardization of the definition and of the technique for endoscopic identification and classification is needed. Studies of reproducibility, interobserver variability, and continuity over time to validate ACF as a clinical end point are required. ACF hold promise as a biomarker for colorectal carcinoma, but additional study is needed.

Aberrant crypt foci in patients with a positive family history of sporadic colorectal cancer

Early detection is crucial in the prevention of colorectal cancer (CRC) deaths. The earliest detectable neoplastic lesion in the colon is the aberrant crypt foci (ACF). A major question is whether ACF are precursors of CRC, and thus, early biomarkers for CRC risk. If so, we hypothesized that the number of ACF would be higher in patients who had a family history of CRC compared to patients without. We counted ACF in the distal 20cm of colon/rectum during 103 colonoscopic examinations using a prototype Close Focus Colonoscope (Olympus Corp.) with methylene blue chromendoscopy. Each patient was asked whether they had a family history of CRC in a first degree relative, or a personal history of CRC or adenoma. Patients answering 'no' to these questions (n=17) had a mean number of ACF of 4.4; the mean was significantly higher in the patients with a positive family history of CRC (9.0, p<0.01; n=43) or a personal history of advanced adenoma (7.5, p<0.05; n=34).

Assessment of rectal aberrant crypt foci by standard chromoscopy and its predictive value for colonic advanced neoplasms

BACKGROUND AND AIMS

Aberrant crypt foci (ACF) are thought to be preneoplastic lesions and are assessed by magnifying chromoscopy with methylene blue staining. The aim of this study was to evaluate the predictive value of rectal ACF recognized by conventional chromoscopy for colonic advanced neoplasms.

METHODS

Total colonoscopy, involving rectal chromoscopy using indigo carmine with standard colonoscopies, was performed on 386 patients. Patients who showed no ACF were classified as Grade 0, and those who had 1-4, 5-9, and 10+ ACF were classified as Grades 1, 2, or 3, respectively. The correlation between ACF grading and the prevalence of colonic advanced neoplasm, any adenoma>or=1 cm in size and/or with villous or tubulovillous morphology, and/or with high-grade dysplasia or invasive cancer, was assessed.

RESULTS

Sixty-three patients were classified as ACF Grade 0, 119 as Grade 1, 116 as Grade 2, and 88 as Grade 3. Colonic advanced neoplasm was observed in 4 patients (6.3%) for Grade 0, 43 (36.1%) for Grade 1, 61 (52.6%) for Grade 2, and 57 (64.8%) for Grade 3. As the ACF grade increased, the chance of a patient having a colonic advanced neoplasm increased. For multivariate analyses, compared with patients with Grade 0, those with Grades 1, 2, or 3 had a greater risk of colonic advanced neoplasm (odds ratio [OR] 9.18, 95% CI 3.08-27.33, OR 20.44, 95% CI 6.81-61.42, and OR 32.94, 95% CI 10.49-103.41, respectively).

CONCLUSIONS

Chromoscopic assessment of rectal ACF by conventional techniques is useful for predicting colonic advanced neoplasms.