Proportion of de novo cancers among colorectal cancers in Japan

The mycobiome in human cancer: analytical challenges, molecular mechanisms, and therapeutic implications

The polymorphic microbiome is considered a new hallmark of cancer. Advances in High-Throughput Sequencing have fostered rapid developments in microbiome research. The interaction between cancer cells, immune cells, and microbiota is defined as the immuno-oncology microbiome (IOM) axis. Fungal microbes (the mycobiome), although representing only ∼ 0.1-1% of the microbiome, are a critical immunologically active component of the tumor microbiome. Accumulating evidence suggests a possible involvement of commensal and pathogenic fungi in cancer initiation, progression, and treatment responsiveness. The tumor-associated mycobiome mainly consists of the gut mycobiome, the oral mycobiome, and the intratumoral mycobiome. However, the role of fungi in cancer remains poorly understood, and the diversity and complexity of analytical methods make it challenging to access this field. This review aims to elucidate the causal and complicit roles of mycobiome in cancer development and progression while highlighting the issues that need to be addressed in executing such research. We systematically summarize the advantages and limitations of current fungal detection and analysis methods. We enumerate and integrate these recent findings into our current understanding of the tumor mycobiome, accompanied by the prospect of novel and exhilarating clinical implications.

White spots around colorectal tumors are cancer-related findings and may aid endoscopic diagnosis: a prospective study in Japan

BACKGROUND/AIMS

During endoscopy, white spots (WS) are sometimes observed around benign or malignant colorectal tumors; however, few reports have investigated WS, and their significance remains unknown. Therefore, we investigated the significance of WS from clinical and pathological viewpoints and evaluated its usefulness in endoscopic diagnosis.

METHODS

Clinical data of patients with lesions diagnosed as epithelial tumors from January 1, 2019, to December 31, 2020, were analyzed (n=3,869). We also performed a clinicopathological analysis of adenomas or carcinomas treated with endoscopic resection (n=759). Subsequently, detailed pathological observations of the WS were performed.

RESULTS

The positivity rates for WS were 9.3% (3,869 lesions including advanced cancer and non-adenoma/carcinoma) and 25% (759 lesions limited to adenoma and early carcinoma). Analysis of 759 lesions showed that the WS-positive lesion group had a higher proportion of cancer cases and larger tumor diameters than the WS-negative group. Multiple logistic analysis revealed the following three statistically significant risk factors for carcinogenesis: positive WS, flat lesions, and tumor diameter ≥5 mm. Pathological analysis revealed that WS were macrophages that phagocytosed fat and mucus and were white primarily because of fat.

CONCLUSIONS

WS are cancer-related findings and can become a new criterion for endoscopic resection in the future.

Predictors of early colorectal cancer metastasis to lymph nodes: providing rationale for therapy decisions

With the improvement of national health awareness and the popularization of a series of screening methods, the number of patients with early colorectal cancer is gradually increasing, and accurate prediction of lymph node metastasis of T1 colorectal cancer is the key to determining the optimal therapeutic solutions. Whether patients with T1 colorectal cancer undergoing endoscopic resection require additional surgery and regional lymph node dissection is inconclusive in current guidelines. However, we can be sure that in early colorectal cancer without lymph node metastasis, endoscopic resection alone does not affect the prognosis, and it greatly improves the quality of life and reduces the incidence of surgical complications while preserving organ integrity. Therefore, it is vital to discriminate patients without lymph node metastasis in T1 colorectal cancer, and this requires accurate predictors. This paper briefly explains the significance and shortcomings of traditional pathological factors, then extends and states the new pathological factors, clinical test factors, molecular biomarkers, and the risk assessment models of lymph node metastasis based on artificial intelligence.

Endoscopic and pathological characteristics of de novo colorectal cancer: Retrospective cohort study

BACKGROUND

Endoscopy has rapidly developed in recent years and has enabled further investigation into the origin and features of intestinal tumors. The small size and concealed position of these tumors make it difficult to distinguish them from nonneoplastic polyps and carcinoma in adenoma (CIA). The invasive depth and metastatic potential determine the operation regimen, which in turn affects the overall survival and distant prognosis. The previous studies have confirmed the malignant features and clinicopathological features of de novo colorectal cancer (CRC).

AIM

To provide assistance for diagnosis and treatment, but the lack of a summary of endoscopic features and assessment of risk factors that differ from the CIA prompted us to conduct this retrospective study.

METHODS

In total, 167 patients with small-sized CRCs diagnosed by endoscopy were reviewed. The patients diagnosed as advanced CRCs and other malignant cancers or chronic diseases that could affect distant outcomes were excluded. After screening, 63 cases were excluded, including 33 de novo and 30 CIA cases. Patient information, including their follow-up information, was obtained from an electronic His-system. The characteristics between two group and risk factors for invasion depth were analyzed with SPSS 25.0 software.

RESULTS

Nearly half of the de novo CRCs were smaller than 1 cm (n = 16, 48.5%) and the majority were located in the distal colon (n = 26, 78.8%). The IIc type was the most common macroscopic type of de novo CRC. In a Pearson analysis, the differential degree, Sano, JNET, and Kudo types, surrounding mucosa, and chicken skin mucosa (CSM) were correlated with the invasion depth (P < 0.001). CSM was a significant risk factor for deep invasion and disturbed judgment of endoscopic ultrasound. A high degree of tumor budding and tumor-infiltrating lymphocytes are accompanied by malignancy. Finally, de novo CRCs have worse outcomes than CIA CRCs.

CONCLUSION

This is the first comprehensive study to analyze the features of de novo CRCs to distinguish them from nonneoplastic polyps. It is also the first study paying attention to CSM invasive depth measurement. This study emphasizes the high metastatic potential of de novo CRCs and highlights the need for more research on this tumor type.

Gut mycobiome: A promising target for colorectal cancer

The human gut is mainly habited by a staggering amount and abundance of bacteria as well as fungi. Gut dysbiosis is believed as a pivotal factor in colorectal cancer (CRC) development. Lately increasing evidence from animal or clinical studies suggested that fungal disturbance also contributed to CRC development. This review summarized the current status of fungal dysbiosis in CRC and highlighted the potential tumorigenic mechanisms of fungi. Then the fungal markers and some therapeutic strategies for CRC were discussed. It would provide a better understanding of the correlation of mycobiota and CRC, and modulating fungal community would be a promising target against CRC.

A Focused Review on Advances in Risk Stratification of Malignant Polyps

Colorectal cancer is the third most common cancer in both men and women in the United States, with most cases arising from precursor adenomatous polyps. Colorectal malignant polyps are defined as cancerous polyps that consist of tumor cells invading through the muscularis mucosae into the underlying submucosa (pT1 tumor). It has been reported that approximately 0.5-8.3% of colorectal polyps are malignant polyps, and the potential for lymph node metastasis in these polyps ranges from 8.5% to 16.1%. Due to their clinical significance, recognition of malignant polyps is critical for clinical teams to make treatment decisions and establish appropriate surveillance schedules after local excision of the polyps. There is a rapidly developing interest in malignant polyps within the literature as a result of an increasing number of identifiable adverse histologic features and recent advancements in endoscopic treatment techniques. The purpose of this paper is to have a focused review of the recent histopathologic literature of malignant polyps.

Copy Number Alterations of Depressed Colorectal Neoplasm Predict the Survival and Response to Oxaliplatin in Proximal Colon Cancer

Depressed colorectal neoplasm exhibits high malignant potential and shows rapid invasiveness. We investigated the genomic profile of depressed neoplasms and clarified the survival outcome and treatment response of the cancers arising from them. We examined 20 depressed and 13 polypoid neoplasms by genome-wide copy number analysis. Subsequently, we validated the identified copy number alterations (CNAs) in an independent cohort of 37 depressed and 42 polypoid neoplasms. Finally, the CNAs were tested as biomarkers in 530 colorectal cancers (CRCs) to clarify the clinical outcome of depressed neoplasms. CNAs in MYC, CCNA1, and BIRC7 were significantly enriched in depressed neoplasms and designated as the D-marker panel. CRCs with a D-marker panel have significantly shorter progression-free survival compared with those without (p = 0.012), especially in stage I (p = 0.049), stages T₁₊₂ (p = 0.027), and proximal cancers (p = 0.002). The positivity of the D-marker panel was an independent risk factor of cancer progression (hazard ratio (95% confidence interval) = 1.52 (1.09–2.11)). Furthermore, the proximal CRCs with D-marker panels had worse overall and progression-free survival when taking oxaliplatin as chemotherapy than those that did not. The D-marker panel may help to optimize treatment and surveillance in proximal CRC and develop a molecular test. However, the current result remains preliminary, and further validation in prospective trials is warranted in the future.

Variations in clinical features and oncologic behaviors of T1 colorectal cancer according to tumor location

BACKGROUND

Different genetic characteristics according to tumor location result in variations in survival rates and treatment responses in advanced colorectal cancer (CRC). However, the effects of tumor location during early CRC are still unclear.

METHODS

Patients with T1 CRC treated between 2003 and 2019 were enrolled from a prospectively collected database. Patients were once divided into four groups, then combined into two groups (right- and left-sided CRC) according to the tumor location, and clinical features and oncologic behaviors were compared.

RESULTS

In total, 458 patients were analyzed. Right-sided CRC had a lower incidence of polypoid type tumor than left-sided CRC (36/126 (28.6%) vs 186/332 (56.0%), p < 0.001). There were no differences in tumor size, pathological grade, pT1 substage and lymphovascular invasion between right- and left-sided CRC. Overall, lymph nodal involvement was observed in 42/458 (9.1%) patients. Right-sided CRC had a lower rate of patients with lymph nodal involvement than left-sided CRC (6/126 (4.8%) vs 36/332 (10.8%), p = 0.04).

CONCLUSION

The present study revealed that there were significant differences in the macroscopic type and the incidence of lymph node involvement between right- and left-sided CRC. The clinical features and oncologic behaviors of T1 CRC are possible to vary according to tumor location.

Cost-effective interventions for breast cancer, cervical cancer, and colorectal cancer: new results from WHO-CHOICE

BACKGROUND

Following the adoption of the Global Action Plan for the Prevention and Control of NCDs 2013-2020, an update to the Appendix 3 of the action plan was requested by Member States in 2016, endorsed by the Seventieth World Health Assembly in May 2017 and provides a list of recommended NCD interventions. The main contribution of this paper is to present results of analyses identifying how decision makers can achieve maximum health gain using the cancer interventions listed in the Appendix 3. We also present methods used to calculate new WHO-CHOICE cost-effectiveness results for breast cancer, cervical cancer, and colorectal cancer in Southeast Asia and eastern sub-Saharan Africa.

METHODS

We used "Generalized Cost-Effectiveness Analysis" for our analysis which uses a hypothetical null reference case, where the impacts of all current interventions are removed, in order to identify the optimal package of interventions. All health system costs, regardless of payer, were included. Health outcomes are reported as the gain in healthy life years due to a specific intervention scenario and were estimated using a deterministic state-transition cohort simulation (Markov model).

RESULTS

Vaccination against human papillomavirus (two doses) for 9-13-year-old girls (in eastern sub-Saharan Africa) and HPV vaccination combined with prevention of cervical cancer by screening of women aged 30-49 years through visual inspection with acetic acid linked with timely treatment of pre-cancerous lesions (in Southeast Asia) were found to be the most cost effective interventions. For breast cancer, in both regions the treatment of breast cancer, stages I and II, with surgery ± systemic therapy, at 95% coverage, was found to be the most cost-effective intervention. For colorectal cancer, treatment of colorectal cancer, stages I and II, with surgery ± chemotherapy and radiotherapy, at 95% coverage, was found to be the most cost-effective intervention.

CONCLUSION

The results demonstrate that cancer prevention and control interventions are cost-effective and can be implemented through a step-wise approach to achieve maximum health benefits. As the global community moves toward universal health coverage, this analysis can support decision makers in identifying a core package of cancer services, ensuring treatment and palliative care for all.

APC:T1556fs and STK11 mutations in duodenal adenomas and adenocarcinomas

PURPOSE

Duodenal adenoma and adenocarcinoma (AC) are rare tumors, and few studies have examined their genetic features. We aimed to determine the key genetic changes in duodenal adenoma and AC, and to clarify the possible involvement of the adenoma-carcinoma sequence in duodenal tumor carcinogenesis.

METHODS

Nineteen duodenal tumors collected by endoscopic mucosal resection or surgical resection were classified as AC, adenoma with high-grade dysplasia (HGD), or adenoma with low-grade dysplasia (LGD) per the World Health Organization tumor classification. When a tumor contained two or more components with different dysplasia grades, the highest grade was assigned as the tumor grade. Representative areas of these components with different grades were microdissected and evaluated by a genomic analysis. Mutational hotspots involving 50 oncogenes and tumor suppressor genes were analyzed by next-generation sequencing, and their association with the dysplasia grade was investigated.

RESULTS

We analyzed 27 tumor components of AC or adenoma, with 11 normal mucosal samples obtained from 19 patients with duodenal tumors. The most prevalent abnormality among 50 genes tested was the KRAS mutation, which was detected in 12/19 (63.2%) patients, followed by APC and TP53 mutations (47.4 and 36.8%, respectively). According to the tumor dysplasia grading of each component, KRAS mutations were found in 5/8 (62.5%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 3/10 (30.0%) tumors with LGD components. TP53 mutations were found in 4/8 (50.0%) tumors with AC components, 3/9 (33.3%) tumors with HGD components, and 1/10 (10.0%) tumors with LGD components. APC mutations were found in 2/8 (25.0%) tumors with AC components, 6/9 (66.7%) tumors with HGD components, and 5/10 (50.0%) tumors with LGD components. Notably, an APC:T1556fs mutation was detected in six cases (31.6%), five of which were adenoma cases. Furthermore, STK11 mutations were confirmed in 2/8 (25.0%) AC cases and in 1/11 (9.1%) adenoma cases.

CONCLUSION

APC:T1556fs and STK11 mutations found in duodenal adenomas/ACs highlight the importance of proteins encoded by these genes in tumor development. APC mutations were identified in duodenal adenomas more frequently than in duodenal ACs, which differed from the observations of typical adenoma-carcinoma sequences seen in colorectal cancer, suggesting the limited involvement of this mechanism in duodenal cancer development.

iTRAQ-Based Proteomics Screen identifies LIPOCALIN-2 (LCN-2) as a potential biomarker for colonic lateral-spreading tumors

The improvement and implementation of a colonoscopy technique has led to increased detection of laterally spreading tumors (LSTs), which are presumed to constitute an aggressive type of colonic neoplasm. Early diagnosis and treatment of LSTs is clinically challenging. To overcome this problem, we employed iTRAQ to identify LST-specific protein biomarkers potentially involved in LST progression. In this study, we identified 2,001 differentially expressed proteins in LSTs using iTRAQ-based proteomics technology. Lipocalin-2 (LCN-2) was the most up-regulated protein. LSTs expression levels of LCN-2 and matrix metallopeptidase-9 (MMP-9) showed positive correlation with worse pathological grading, and up-regulation of these proteins in LSTs was also reflected in serum. Furthermore, LCN-2 protein overexpression was positively correlated with MMP-9 protein up-regulation in the tumor tissue and serum of LST patients (former r_s = 0.631, P = 0.000; latter r_s = 0.815, P = 0.000). Our results suggest that LCN-2 constitutes a potential biomarker for LST disease progression and might be a novel therapeutic target in LSTs.

TP53 mutation at early stage of colorectal cancer progression from two types of laterally spreading tumors

Although most sporadic colorectal cancers (CRC) are thought to develop from protruded adenomas through the adenoma-carcinoma sequence, some CRC develop through flat lesions, so-called laterally spreading tumors (LST). We previously analyzed epigenetic aberrations in LST and found that LST are clearly classified into two molecular subtypes: intermediate-methylation with KRAS mutation and low-methylation with absence of oncogene mutation. Intermediate-methylation LST were mostly granular type LST (LST-G) and low-methylation LST were mostly non-granular LST (LST-NG). In the present study, we conducted a targeted exon sequencing study including 38 candidate CRC driver genes to gain insight into how these genes modulate the development of LST. We identified a mean of 11.5 suspected nonpolymorphic variants per sample, including indels and non-synonymous mutations, although there was no significant difference in the frequency of total mutations between LST-G and LST-NG. Genes associated with RTK/RAS signaling pathway were mutated more frequently in LST-G than LST-NG (P = 0.004), especially KRAS mutation occurring at 70% (30/43) of LST-G but 26% (13/50) of LST-NG (P < 0.0001). Both LST showed high frequency of APC mutation, even at adenoma stage, suggesting its involvement in the initiation stage of LST, as it is involved at early stage of colorectal carcinogenesis via adenoma-carcinoma sequence. TP53 mutation was never observed in adenomas, but was specifically detected in cancer samples. TP53 mutation occurred during development of intramucosal cancer in LST-NG, but during development of cancer with submucosal invasion in LST-G. It is suggested that TP53 mutation occurs in the early stages of cancer development from adenoma in both LST-G and LST-NG, but is involved at an earlier stage in LST-NG.

Methylation epigenotypes and genetic features in colorectal laterally spreading tumors

Aberrant DNA methylation plays an important role in genesis of colorectal cancer (CRC). Previously, we identified Group 1 and Group 2 methylation markers through genome-wide DNA methylation analysis, and classified CRC and protruded adenoma into three distinct clusters: high-, intermediate- and low-methylation epigenotypes. High-methylation epigenotype strongly correlated with BRAF mutations and these aberrations were involved in the serrated pathway, whereas intermediate-methylation epigenotype strongly correlated with KRAS mutations. Here, we investigated laterally spreading tumors (LSTs), which are flat, early CRC lesions, through quantitative methylation analysis of six Group 1 and 14 Group 2 methylation markers using pyrosequencing. Gene mutations in BRAF, KRAS and PIK3CA, and immunostaining of TP53 and CTNNB1 as well as other clinicopathological factors were also evaluated. By hierarchical clustering using methylation information, LSTs were classified into two subtypes; intermediate-methylation epigenotype correlating with KRAS mutations (p = 9 × 10(-4)) and a granular morphology (LST-G) (p = 1 × 10(-7)), and low-methylation epigenotype correlating with CTNNB1 activation (p = 0.002) and a nongranular morphology (LST-NG) (p = 1 × 10(-7)). Group 1 marker methylation and BRAF mutations were barely detected, suggesting that high-methylation epigenotype was unlikely to be involved in LST development. TP53 mutations correlated significantly with malignant transformation, regardless of epigenotype or morphology type. Together, this may suggest that two molecular pathways, intermediate methylation associated with KRAS mutations and LST-G morphology, and low methylation associated with CTNNB1 activation and LST-NG morphology, might be involved in LST development, and that involvement of TP53 mutations could be important in both subtypes in the development from adenoma to cancer.

Clinicopathological differences of laterally spreading tumors arising in the colon and rectum

PURPOSE

Laterally spreading tumors (LST) have been recognized worldwide. The aim of our retrospective study was to evaluate the clinicopathological differences of LST arising in the colon and rectum.

METHODS

We investigated the clinical records of consecutive patients with LST that were endoscopically or surgically resected at our hospital between February 2006 and March 2011. LST were classified into three types: granular-homogenous (LST-GH), granular-nodular mixed (LST-GM), and nongranular (LST-NG) types. We also defined the hardly elevated flat lesion with a dilated pit pattern that occurs at the margins of LST as the "skirt." The clinicopathological characteristics of the LST arising in the colon and rectum, including the presence of the skirt, were compared.

RESULTS

A total of 496 colorectal LST in 435 patients were examined. LST-GM was predominant in the rectum, whereas LST-NG was predominant in the colon (p < 0.001). The mean tumor size was larger in the rectum (39.3 ± 17.9 mm) than the colon (25.8 ± 13.6 mm) (p < 0.001). Low-grade dysplasia frequency was lower in the rectum than the colon (4 vs. 37%, p < 0.001). The skirt was identified in 15 lesions (3.0%), with a higher incidence in the rectum than the colon (17 vs. 0.5%, p < 0.001). The skirt was found only in LST-GM.

CONCLUSIONS

A greater proportion of LST-GM, greater mean size, and lower incidence of low-grade dysplasia were found in rectal LST. The skirt was a novel and unique finding, primarily observed in rectal LST-GM cases.

What clinicians wish to know about benign colorectal polyps: an operative classification

INTRODUCTION

In recent years we assisted to a real "boom" of colorectal polyps, mainly due to the diffusion of screening procedures and of colonoscopy. This new "Polyp Epidemic" raises a series of problems and challenges. It became clear that many syndromes are defined by the number, histological type and location of polyps, together with extraintestinal manifestations and, in most cases, specific molecular changes. This paper discusses some of the above mentioned points, focusing on the relative role of endoscopists and pathologists. The objective is to reach an operative classification of the most common polyps observed in daily practice which might be of help for the identification of inherited syndromes.

METHODS AND RESULTS

Six main histological types of polyps are defined and underlined: Adenoma, hyperplastic/serrated, hamartoma, ganglioneuroma, mixed, inflammatory. The importance of a brief description, in pathology reports, of each type of polyps is fundamental for a correct diagnosis. Each of the defined polyps is associated with inherited syndromes whose genetic basis has recently been elucidated. Relevant information should be given, and separated from additional (and not strictly necessary) information.

RECOMMENDATIONS

A correct polyp analysis is a valuable element for identifying specific inherited syndromes. Polyps represent a precious tool for planning screening and follow-up in a given individual. In addition, these lesions focus the interest of clinicians toward syndrome which were considered as rare diseases; indeed, the explosion of molecular biology and the diffusion of colonoscopy revealed that these conditions are frequent and amenable of treatment.

Pathological stage significantly predicts survival in colorectal cancer patients: a study from two tertiary care centers in India

SUMMARY

Aims: An increase in incidence of early-onset colorectal cancer (EOCRC) in developing countries, including India, is reported recently; however, systematic analyses of clinico-pathological features and disease prognosis has seldom been undertaken. Materials & methods: We studied clinical data pertaining to 1259 colorectal adenocarcinoma patients from two tertiary cancer centers in south India. Results: Approximately 45% of patients were aged below 50 years and poor grade and late-stage tumors were significantly associated with early disease onset. Although tumor grade and stage significantly influenced disease-free survival independently, significant association between survival and age of onset or tumor location was not detected unlike previous observations. Conclusion: Given the sizeable proportion of EOCRC, implementation of the revised Bethesda guidelines may not be tenable in India. More importantly, the previous observation of EOCRC being significantly associated with poor survival could, in part, be due to a higher proportion of advanced-stage tumors.

Clinicopathological characteristics of T1 colorectal cancer without background adenoma

AIM

Background adenoma (BGA) is defined as benign adenomatous tissue contiguous to resected carcinomas, and the absence of BGA in a tumour is considered a histological criterion of de novo cancers. The present study aimed to identify the clinicopathological characteristics of T1 colorectal cancer (CRC) without BGA.

METHOD

A retrospective review was carried out of prospectively collected data from two centres: the National Cancer Center, Korea; and Chonnam National University Hwasun Hospital, Korea. A total of 590 patients with T1 CRC, treated by endoscopic or surgical resection between January 2001 and August 2011, were enrolled. Details regarding gender, age, tumour location, endoscopic gross type, tumour size, depth of submucosal (SM) invasion, angiolymphatic invasion, tumour grade, budding and lymph node (LN) metastasis were evaluated with regard to the presence or absence of BGA.

RESULTS

BGA was absent in 197 (33.4%) patients. Tumour size <20 mm, flat or depressed type, deep SM depth and tumour budding were associated with the absence of BGA in univariate and multivariate analyses (P < 0.05). In surgically resected patients, LN metastases were significantly associated with the absence of BGA (P = 0.022).

CONCLUSION

T1 CRC without BGA presented several characteristics of small size (<20 mm), flat or depressed type, deep SM depth (SM 2/3), LN metastasis and tumour budding. These results indicate that de novo cancers may have a more invasive potential.

Colorectal cancer screening in Asia

INTRODUCTION

The incidence and mortality of colorectal cancer are rapidly rising in several countries in Asia. However, screening guidelines are lacking.

SOURCES OF DATA

Review of literature and local data published in peer review journals.

AREAS OF AGREEMENT

The incidence, anatomical distribution and mortality of colorectal cancer among Asian populations are comparable to those in Western countries. Flat and depressed colonic lesions are not uncommon. Male gender, smoking, obesity, metabolic syndrome and family history are risk factors for colorectal cancer. Certain ethnic groups in Asia have increased susceptibility to colorectal cancer. Faecal occult blood test, flexible sigmoidoscopy and colonoscopy are recommended options for colorectal cancer screening in Asia. Regular screening should start at the age of 50 years.

AREAS OF CONTROVERSY

The optimal screening method in Asia remains unclear. Faecal immunochemical test has been suggested as the first choice of screening test in countries with limited resources. The role of nurse endoscopists in performing endoscopic procedures for colorectal cancer screening in Asia has not been defined.

GROWING POINTS

There is low public awareness and little support by health authorities for screening and prevention of this emerging disease.

AREAS TIMELY FOR DEVELOPING RESEARCH

Screening for colorectal cancer should be a national health priority in most Asian countries. Studies on barriers to screening, education of the public and engagement of family physicians are important strategies in promoting colorectal cancer screening. With more health-care support, increased public acceptance and better access to the general population, colorectal cancer screening in Asia can be rewarding.

Transparent cap colonoscopy versus standard colonoscopy to improve caecal intubation

BACKGROUND

Colonoscopy is considered the gold-standard investigation for screening and diagnosis of colorectal cancer. It is also becoming increasingly desirable for assessment, management, diagnosis and follow-up of other colorectal diseases, such as inflammatory bowel diseases and acute diverticulitis. Hence, due to the increasing demand for colonoscopy, devices to advance examination techniques are highly sought-after and the colonoscope with the transparent cap could be one of these.

OBJECTIVES

To identify and review all relevant data in order to determine whether colonoscopy with a transparent cap is a more effective diagnostic tool than colonoscopy.

SEARCH METHODS

We searched the MEDLINE, EMBASE and CINAHL databases, and the Cochrane Central Register of Controlled Trials for all randomised controlled trials (RCTs) comparing the use of colonoscopy with a transparent cap with standard colonoscopy.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials which compared the use of colonoscopy with a transparent cap with standard colonoscopy.

DATA COLLECTION AND ANALYSIS

Data on study methods, participants, interventions used and outcomes measured was extracted from each study. Data was entered into the Cochrane Review Manager software (RevMan 5.0, 2008) and analysed using Cochrane MetaView.

MAIN RESULTS

In the present meta-analysis, we considered 14 randomised controlled trials so far published. The findings of our work indicate that colonoscopy with transparent cap has a faster caecal intubation time when compared with standard colonoscopy. Reviewing studies individually would also seem to favour colonoscopy with transparent cap for polyp detection rate and pain during procedure but due to lack of comparable data meta-analysis was not feasible.

AUTHORS' CONCLUSIONS

This review suggests that a transparent cap on the end of the colonoscope may give a marginally faster caecal intubation time compared with standard colonoscopy. It also suggests that there is a better polyp detection rate and less pain with the cap. However, the authors feel that further randomised controlled trials in this area would provide more clinically significant information on this adjunct to colonoscopy.

Clinicopathological differences of colorectal cancers according to tumor origin: Identification of possibly de novo lesions

Colorectal cancer (CRC) is considered to develop through the conventional adenoma-carcinoma sequence. However, the existence of de novo carcinogenesis, without any intervening precursor lesions, has been suggested for certain morphologically different tumors lacking polypoid characteristics. The presence of such tumors, along with their correlation with cardinal clinicopathological parameters, such as stage, grade and site, was retrospectively investigated in a series of 119 surgically treated CRC cases. The absence of particular polypoid characteristics (adenomatous remnants or coexisting polyps in the tumor vicinity) in combination with an infiltrative (or ulceroinfiltrative) growth pattern, were the criteria defining the nonpolypoid origin. The recorded frequencies of remnants, coexisting polyps and infiltrative tumors were 7, 5, 9 and 32%, respectively. The incidence of cases meeting the above-mentioned criteria was 28.5%. These nonpolypoid lesions exhibited a predilection for proximal anatomical site (P=0.04), probably associated with their infiltrative pattern. Most importantly, de novo lesions (unlike polypoid) were rarely found among cases with indolent tumor characteristics (stage I or grade I, P=0.008), showing a considerably different overall pattern of distribution by stage and grade as compared to that of polypoid tumors (P=0.03). The fact that nonpolypoid CRCs appeared to be clinicopathologically different from their polypoid counterparts is supportive of possible de novo origin and suggestive of a likely worse clinical behavior. The impact of these findings should be investigated to determine potential applications in the diagnosis, treatment and surveillance of these lesions.

Comparison of various strategies for colorectal cancer screening tests

INTRODUCTION

Colorectal cancer (CRC) is one of the most serious health problems worldwide and thus it is important to assess health and economic impacts of preventative CRC screening strategies.

METHODS

For this reason, a theoretical model based on Markov chains is proposed to compare these strategies: fecal occult blood test, capsule endoscopy, once-life and twice-life colonoscopy, and no screening. The model predicts the health state of a population of individuals aged from 50 to 75 years.

RESULTS

The numerical results show that the optimal timing for a once-lifetime colonoscopy screening method is before the age of 50 and that the twice-lifetime colonoscopy is the best screening strategy with respect to CRC incidence. In contrast, it is the most expensive one if the CRC treatment costs are not included. The model predicts that there is a minimal CRC incidence in the population when the second colonoscopy is appropriately timed. By using specific data, this age was found to be 59 years.

CONCLUSION

The screening strategies probably save expenses on the treatment of the population and at the same time decreases mortality. Optimized twice-lifetime colonoscopy seems to be the most efficient strategy with respect to mortality and overall costs including subsequent treatment.

Proportion of flat- and depressed-type and laterally spreading tumor among advanced colorectal neoplasia

BACKGROUND & AIMS

Flat- and depressed-type neoplasias along with laterally spreading tumors (LSTs) have been reported in colorectal neoplasias. We estimated the prevalence of flat and depressed types and LSTs along with their proportion among advanced neoplasias in a large average-risk population undergoing screening colonoscopy.

METHODS

This was a cross-sectional study performed at a single, general community institution, with subjects who were 40 to 79 years old, asymptomatic, and who had undergone their first colonoscopy for screening between 2003 and 2009 (n = 4910). Among the neoplasias detected, advanced neoplasias were morphologically classified as the polypoid type, flat and depressed type, or LST. We determined the prevalence and proportion for each type among the advanced neoplasias, with morphologies defined according to the Japanese endoscopic classification.

RESULTS

Advanced neoplasias were detected in 7.9% of men, 4.7% of women, and 6.1% of overall subjects. The polypoid type, the flat and depressed types, and the LSTs accounted for 75.3%, 7.5%, and 17.2% of advanced neoplasia, respectively. There was a high proportion of T1 cancers among the depressed types (40%). Approximately 80% of LSTs were located on the right side of the colon and more than 30% of LSTs showed high-grade dysplasia or T1 cancer.

CONCLUSIONS

Most advanced neoplasias detected were of the polypoid type. LSTs accounted for a considerable proportion among advanced neoplasia and tended to be located on the right side of the colon. The influences of any LSTs need to be taken into consideration for preventing colorectal cancer.

Transparent Cap Colonoscopy versus Standard Colonoscopy for Investigation of Gastrointestinal Tract Conditions

BACKGROUND

Colonoscopy is considered the gold-standard investigation for screening and diagnosis of colorectal cancer. It is also becoming increasingly desirable for assessment, management, diagnosis and follow-up of other colorectal diseases, such as inflammatory bowel diseases and acute diverticulitis. Hence, due to the increasing demand for colonoscopy, devices to advance examination techniques are highly sought-after and the colonoscope with the transparent cap could be one of these.

OBJECTIVES

To identify and review all relevant data in order to determine whether colonoscopy with a transparent cap is a more effective diagnostic tool than colonoscopy.

SEARCH STRATEGY

We searched the MEDLINE, EMBASE and CINAHL databases, and the Cochrane Central Register of Controlled Trials for all randomised controlled trials (RCTs) comparing the use of colonoscopy with a transparent cap with standard colonoscopy.

SELECTION CRITERIA

Studies were included if they were randomised controlled trials which compared the use of colonoscopy with a transparent cap with standard colonoscopy.

DATA COLLECTION AND ANALYSIS

Data on study methods, participants, interventions used and outcomes measured was extracted from each study. Data was entered into the Cochrane Review Manager software (RevMan 5.0, 2008) and analysed using Cochrane MetaView.

MAIN RESULTS

In the present meta-analysis, we considered for the first time all five randomised controlled trials so far performed. The findings of our work indicate that colonoscopy with transparent cap has a faster caecal intubation time when compared with standard colonoscopy. Reviewing studies individually would also seem to favour colonoscopy with transparent cap for polyp detection rate and pain during procedure but due to lack of comparable data meta-analysis was not feasible.

AUTHORS' CONCLUSIONS

This review suggests that a transparent cap on the end of the colonoscope may give a marginally faster caecal intubation time compared with standard colonoscopy. It also suggests that there is a better polyp detection rate and less pain with the cap. However, the authors feel that further randomised controlled trials in this area would provide more clinically significant information on this adjunct to colonoscopy.

Polyp surveillance

Surveillance after colonic polypectomy is important to detect and remove missed synchronous polyps and cancers and new metachronous polyps or cancers. The authors review methods of surveillance and the risk of recurrent adenomas and provide surveillance recommendations.

The natural history of non-polypoid colorectal neoplasms

Despite their importance, little is known about the natural history of non-polypoid colorectal neoplasms (NP-CRN). This article will summarize the available data to gain some estimates of the natural history of NP-CRN.

Prevalence and clinicopathological features of nonpolypoid colorectal neoplasms: should we pay more attention to identifying flat and depressed lesions?

Flat and depressed (nonpolypoid) colorectal lesions have been described for over two decades by Japanese investigators. These neoplastic lesions are typically smaller than polypoid ones and can be more difficult to identify during screening colonoscopy. In particular, depressed type colorectal lesions are usually small in size, with a number of studies showing them to be at greater risk for developing high-grade dysplasia or submucosal invasive cancer. It has also been suggested that they may follow a different carcinogenic pathway to flat elevated or protruding adenomas. This paper summarizes recent data of nonpolypoid colorectal neoplasms from Western and Asian countries.

Prevalence and characteristics of nonpolypoid colorectal neoplasm in an asymptomatic and average-risk Chinese population

BACKGROUND AND AIMS

Evidence from Japanese studies suggests that nonpolypoid colorectal neoplasia (NP-CRN) tends to be more pathologically advanced than polypoid neoplasia. However, data are limited regarding the prevalence of NP-CRN in an average-risk population. In addition, the diagnostic yield of the fecal occult blood test (FOBT) in relation to different types of colorectal neoplasms remains unclear. We prospectively investigated the prevalence and characteristics of polypoid and nonpolypoid colorectal lesions in an asymptomatic and average-risk Chinese population.

METHODS

The study included 12,731 asymptomatic Chinese subjects (8372 of whom were average-risk subjects) who underwent screening colonoscopy. The prevalence, histopathologic findings, and topographic distribution of polypoid and nonpolypoid colorectal lesions were determined and analyzed. The diagnostic yield of FOBT, in relation to lesion morphology, also was assessed.

RESULTS

NP-CRN was detected in 552 (4.3%) asymptomatic and 348 (4.2%) average-risk subjects. The prevalence of depressed NP-CRN was 0.18% in both asymptomatic and average-risk subjects. A higher proportion of smaller-sized but high-grade dysplasia and invasive carcinoma beyond the submucosal layer was noted for depressed NP-CRN compared with flat NP-CRN or polypoid neoplasia. The diagnostic yield of FOBT was comparable in depressed lesions and their polypoid counterparts.

CONCLUSIONS

The prevalence of NP-CRN is substantial in both asymptomatic and average-risk Chinese individuals. Some subcategories of NP-CRN in this population tend to have more advanced pathologic characteristics. These findings may lead to modification of screening and prevention strategies for colorectal cancer.

Improved colorectal adenoma detection with a transparent retractable extension device

BACKGROUND AND AIMS

Colonoscopy is an excellent but imperfect modality for colorectal cancer screening and prevention. We studied the effects of a retractable transparent extension device on adenoma detection rate as well as on intubation and withdrawal times.

METHODS

Colonoscopy with or without the transparent retractable extension (TRE) was performed by one endoscopist. A subset of patients with colonic adenomas were randomized to repeat colonoscopy with or without a TRE device. Adenoma removal was done at the second colonoscopy. The principal outcome parameters were the cecal intubation time, withdrawal time, and the number, size, and location of adenomas detected.

RESULTS

The study was done in two parts. First, 835 patients underwent colonoscopy with or without the TRE. The patients' demographic characteristics, the indications for colonoscopy, the cecal intubation time and withdrawal time, and the proportion of patients with adenomas (29.0%vs 24.1%) (P= 0.11) were similar between the two techniques. The number of adenomas detected with the TRE was significantly higher than that without the extension (205 vs 150) (P= 0.04). Second, 60 patients with adenomas found at colonoscopy without the device were randomized to repeat colonoscopy within 3 months. Hood-assisted colonoscopy revealed 20% more adenomas than the initial procedure compared to a 4% increase without the hood (P= 0.029).

CONCLUSIONS

Colonoscopy with a TRE device improved the adenoma detection rate without affecting intubation and withdrawal times.

Prolongation of the period between biopsy and EMR can influence the nonlifting sign in endoscopically resectable colorectal cancers

BACKGROUND

The nonlifting sign is widely used for evaluating the invasion depth of colorectal tumors, and it is commonly accepted that EMR is contraindicated for colorectal tumors with a nonlifting sign because of the probability of massive submucosal invasion.

OBJECTIVE

To identify the clinicopathologic factors that affect the nonlifting sign in submucosal invasive colorectal carcinoma (SICC).

DESIGN

Details regarding a history of biopsy, postbiopsy days, tumor location, tumor configuration, tumor size, depth of submucosal invasion, histologic type, adenomatous remnants, and angiolymphatic invasion were studied in relation to the nonlifting sign.

SETTING

National Cancer Center, Korea.

PATIENTS

The study involved 76 patients with SICC treated by endoscopic or surgical resection, in whom the tumor was examined for the nonlifting sign from 2001 to 2006.

RESULTS

The nonlifting sign was observed in 15 cases (19.7%). A deep submucosal invasion, a history of biopsy, and the absence of adenomatous remnants were identified as factors affecting the nonlifting sign in univariate and multivariate analyses (P < .05). An increase in the number of postbiopsy days was associated with the nonlifting sign in endoscopically resectable SICC, and all 11 sm1 cancer cases with fewer than 21 postbiopsy days showed lifting.

CONCLUSIONS

A history of biopsy and the absence of adenomatous remnants, in addition to deep submucosal invasion, were found to influence the nonlifting sign in SICC. It may be best that mechanical stimulation such as forceps biopsies are minimized before EMR, and EMR should be tried as soon as possible if biopsy was performed.