Cancer prevention in ulcerative colitis: long-term outcome following fluorescence-guided colonoscopy

Colorectal cancer risk of flat low-grade dysplasia in inflammatory bowel disease: a systematic review and proportion meta-analysis

BACKGROUND

To date, the optimal management of patients with inflammatory bowel disease (IBD) and flat low-grade dysplasia (fLGD) of the colon or rectum remains controversial.

METHODS

A systematic review was reported in accordance with PRISMA 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Patients diagnosed with fLGD on surveillance endoscopy were pooled from studies published between 2000 and 2020. Advanced neoplasia was defined by the presence of HGD, CRC or small bowel adenocarcinoma detected on subsequent surveillance endoscopy or from examination of resection specimens. We estimated the pooled annual incidence rate of colorectal cancer (CRC) and advanced neoplasia, and the risk factors associated with neoplastic progression.

RESULTS

We identified 24 articles and 738 IBD patients were diagnosed with fLGD on endoscopy. Two hundred thirty-six patients (32%) underwent immediate surgery with surgical specimens demonstrating CRC in 8 patients (pooled prevalence, 8.66%; 95% CI 3.58-19.46) and HGD (high grade dysplasia) in 11 patients (pooled prevalence, 13.97%; 95% CI 5.65-30.65). Five hundred-two patients (68%) underwent endoscopic surveillance with 63 patients with fLGD progressing to advanced neoplasia during endoscopic surveillance (38 HGD, 24 CRC and one patient developing small bowel adenocarcinoma). The mean duration of follow-up after fLGD diagnosis was 71 months (10.9-212). The pooled incidence of CRC and advanced neoplasia was 0.5 (95% CI 0.23-0.77) and 1.71 per 100 patient-year (95% CI 0.88-2.54) respectively. The use of corticosteroids and location of fLGD in the distal colon were significantly associated with neoplastic progression.

CONCLUSIONS

This study provides a summary incidence rate of CRC and advanced neoplasia in patients with IBD and fLGD to inform surgeons' and endoscopists' decision-making thus reducing potential ineffective treatments.

Fluorescence Imaging of Breast Tumors and Gastrointestinal Cancer

Optical imaging offers a high potential for noninvasive detection and therapy of cancer in humans. Recent advances in instrumentation for diffuse optical imaging have led to new capabilities for the detection of cancer in highly scattering tissue such as the female breast. In particular, fluorescence imaging was made applicable as a sensitive technique to image molecular probes in vivo. We review recent developments in the detection of breast cancer and fluorescence-guided surgery of the breast by contrast agents available for application on humans. Detection of cancer has been investigated with the unspecific contrast agents "indocyanine green" and "omocianine" so far. Hereby, indocyanine green was found to offer high potential for the differentiation of malignant and benign lesions by exploiting vessel permeability for macromolecules as a cancer-specific feature. Tumor-specific molecular targeting and activatable probes have been investigated in clinical trials for fluorescence-guided tumor margin detection. In this application, high spatial resolution can be achieved, since tumor regions are visualized mainly at the tissue surface. As another example of superficial tumor tissue, imaging of lesions in the gastrointestinal tract is discussed. Promising results have been obtained on high-risk patients with Barrett´s esophagus and with ulcerative colitis by administering 5-aminolevulinic acid which induces accumulation of protoporphyrin IX serving as a tumor-specific fluorescent marker. Time-gated fluorescence imaging and spectroscopy are effective ways to suppress underlying background from tissue autofluorescence. Furthermore, recently developed tumor-specific molecular probes have been demonstrated to be superior to white-light endoscopy offering new ways for early detection of malignancies in the gastrointestinal tract.

A qualitative transcriptional signature for the early diagnosis of colorectal cancer

Currently, using biopsy specimens for the early diagnosis of colorectal cancer (CRC) is not entirely reliable due to insufficient sampling amount and inaccurate sampling location. Thus, it is necessary to develop a signature that can accurately identify patients with CRC under these clinical scenarios. Based on the relative expression orderings of genes within individual samples, we developed a qualitative transcriptional signature to discriminate CRC tissues, including CRC adjacent normal tissues from non-CRC individuals. The signature was validated using multiple microarray and RNA sequencing data from different sources. In the training data, a signature consisting of 7 gene pairs was identified. It was well validated in both biopsy and surgical resection specimens from multiple datasets measured by different platforms. For biopsy specimens, 97.6% of 42 CRC tissues and 94.5% of 163 non-CRC (normal or inflammatory bowel disease) tissues were correctly classified. For surgically resected specimens, 99.5% of 854 CRC tissues and 96.3% of 81 CRC adjacent normal tissues were correctly identified as CRC. Notably, we additionally measured 33 CRC biopsy specimens by the Affymetrix platform and 13 CRC surgical resection specimens, with different proportions of tumor epithelial cells, ranging from 40% to 100%, by the RNA sequencing platform, and all these samples were correctly identified as CRC. The signature can be used for the early diagnosis of CRC, which is also suitable for minimum biopsy specimens and inaccurately sampled specimens, and thus has potential value for clinical application.

Quantitative or qualitative transcriptional diagnostic signatures? A case study for colorectal cancer

Background

Due to experimental batch effects, the application of a quantitative transcriptional signature for disease diagnoses commonly requires inter-sample data normalization, which would be hardly applicable under common clinical settings. Many cancers might have qualitative differences with the non-cancer states in the gene expression pattern. Therefore, it is reasonable to explore the power of qualitative diagnostic signatures which are robust against experimental batch effects and other random factors.

Results

Firstly, using data of technical replicate samples from the MicroArray Quality Control (MAQC) project, we demonstrated that the low-throughput PCR-based technologies also exist large measurement variations for gene expression even when the samples were measured in the same test site. Then, we demonstrated the critical limitation of low stability for classifiers based on quantitative transcriptional signatures in applications to individual samples through a case study using a support vector machine and a naïve Bayesian classifier to discriminate colorectal cancer tissues from normal tissues. To address this problem, we identified a signature consisting of three gene pairs for discriminating colorectal cancer tissues from non-cancer (normal and inflammatory bowel disease) tissues based on within-sample relative expression orderings (REOs) of these gene pairs. The signature was well verified using 22 independent datasets measured by different microarray and RNA_seq platforms, obviating the need of inter-sample data normalization.

Conclusions

Subtle quantitative information of gene expression measurements tends to be unstable under current technical conditions, which will introduce uncertainty to clinical applications of the quantitative transcriptional diagnostic signatures. For diagnosis of disease states with qualitative transcriptional characteristics, the qualitative REO-based signatures could be robustly applied to individual samples measured by different platforms.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4446-y) contains supplementary material, which is available to authorized users.

Incidence, Risk Factors, and Outcomes of Colorectal Cancer in Patients With Ulcerative Colitis With Low-Grade Dysplasia: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Little is known about outcomes of patients with ulcerative colitis with low-grade dysplasia (UC-LGD). We estimated the incidence of and risk factors for progression to colorectal cancer (CRC) in cohorts of patients with UC-LGD who underwent surveillance (surveillance cohort), and the prevalence of dysplasia-related findings among patients who underwent colectomy for UC-LGD (surgical cohort).

METHODS

We performed a systematic literature review through June 1, 2016, to identify cohort studies of adults with UC-LGD. We estimated pooled incidence rates of CRC and risk factors associated with dysplasia progression in surveillance cohorts, and prevalence of synchronous advanced neoplasia (CRC and/or high-grade dysplasia) in surgical cohorts.

RESULTS

In 14 surveillance cohort studies of 671 patients with UC-LGD (52 developed CRC), the pooled annual incidence of CRC was 0.8% (95% confidence interval [CI], 0.4-1.3); the pooled annual incidence of advanced neoplasia was 1.8% (95% CI, 0.9-2.7). Risk of CRC was higher when LGD was diagnosed by expert gastrointestinal pathologist (1.5%) than by community pathologists (0.2%). Factors significantly associated with dysplasia progression were concomitant primary sclerosing cholangitis (odds ratio [OR], 3.4; 95% CI, 1.5-7.8), invisible dysplasia (vs visible dysplasia; OR, 1.9; 95% CI, 1.0-3.4), distal location (vs proximal location; OR, 2.0; 95% CI, 1.1-3.7), and multifocal dysplasia (vs unifocal dysplasia; OR, 3.5; 95% CI, 1.5-8.5). In 12 surgical cohort studies of 450 patients who underwent colectomy for UC-LGD, 34 patients had synchronous CRC (pooled prevalence, 17%; 95% CI, 8-33).

CONCLUSION

In a systematic review of the literature, we found that among patients with UC-LGD under surveillance, the annual incidence of progression to CRC was 0.8%; differences in rates of LGD diagnosis varied with pathologists' level of expertise. Concomitant primary sclerosing cholangitis, invisible dysplasia, distal location, and multifocal LGD are high-risk features associated with dysplasia progression.

Colorectal Cancer in Patients With Inflammatory Bowel Disease: The Need for a Real Surveillance Program

The association between inflammatory bowel disease (IBD) and colorectal cancer (CRC) has been widely shown. This association is responsible for 10% to 15% of deaths in patients with IBD, even if according to some studies, the risk of developing CRC seems to be decreased. An adequate surveillance of patients identified as at-risk patients, might improve the management of IBD-CRC risk. In this article we review the literature data related to IBD-CRC, analyze potential risk factors such as severity of inflammation, duration, and extent of IBD, age at diagnosis, sex, family history of sporadic CRC, and coexistent primary sclerosing cholangitis, and update epidemiology on the basis of new studies. Confirmed risk factors for IBD-CRC are severity, extent, and duration of colitis, the presence of coexistent primary sclerosing cholangitis, and a family history of CRC. Current evidence-based guidelines recommend surveillance colonoscopy for patients with colitis 8 to 10 years after diagnosis, further surveillance is decided on the basis of patient risk factors. The classic white light endoscopy, with random biopsies, is now considered unsatisfactory. The evolution of technology has led to the development of new techniques that promise to increase the effectiveness of the monitoring programs. Chromoendoscopy has already proved highly effective and several guidelines suggest its use with a target biopsy. Confocal endomicroscopy and autofluorescence imaging are currently being tested and for this reason they have not yet been considered as useful in surveillance programs.

Colorectal cancer in colitis: a relic of the past?

The incidence of dysplasia and colorectal cancer in patients with long-standing colitis seems to be decreasing and controversy surrounds our detection and management strategies. Dysplasia is rarer, flatter, and smaller than in previous decades. Current surveillance guidelines, onerous in terms of colonoscopic workload and an emphasis on random biopsies, have yet to be shown to prevent colon cancers and colon cancer death in these patients. The evidence base for adjunct techniques such as chromoendoscopy is strong but adoption has been slow. We need to better risk-stratify patients with colitis and direct diminishing medical resources accordingly. Modulating dysplasia and cancer risk will involve optimizing medical therapies and focusing our colonoscopic efforts on those who will most likely benefit.

Surveillance in inflammatory bowel disease: chromoendoscopy and digital mucosal enhancement

Patients with long-standing inflammatory bowel disease (IBD) have an increased risk of developing colorectal cancer. Performing periodic dysplasia screening and surveillance may diminish this risk. To date, chromoendoscopy is the only technique that has consistently yielded positive results in large, well-designed dysplasia-detection trials. Most major society guidelines endorse chromoendoscopy as an adjunct, accepted, or preferred dysplasia-detection tool. This review outlines the available endoscopic technologies for the detection of dysplasia in IBD, considers the evidence supporting their use, and assesses which modalities are ready for use in clinical practice.

Adenoma-like and non-adenoma-like dysplasia-associated lesion or mass in ulcerative colitis

Ulcerative colitis (UC) patients have an increased risk of colorectal cancer. UC has two general patterns of dysplasia, which are commonly classified as adenoma-like dysplasia-associated lesion or mass (DALM) and non-adenoma-like DALM. The latter has a high risk of concurrent malignancy and often requires a colectomy. Unfortunately, non-adenoma-like DALMs sometimes have endoscopic features similar to those of adenoma-like DALMs. Therefore, new endoscopic techniques to distinguish between these two kinds of DALM have been proposed.