Optimization of the surveillance strategy in patients with colorectal adenomas: A combination of clinical parameters and index colonoscopy findings

Dynamic adenoma detection rate influences the risk of metachronous advanced neoplasia after removal of low-risk findings in screening colonoscopy

BACKGROUND

Endoscopists' adenoma detection rate (ADR) may change over time and dynamic ADR has been identified as a predictor for post-screening colorectal cancer. However, whether low-risk findings removed by an endoscopist with a lower dynamic ADR benefit from a shorter duration of follow-up requires further research.

METHODS

We conducted a two-center retrospective study of individuals who had low-risk findings removed and underwent subsequent surveillance colonoscopy. Endoscopists' dynamic ADR was the ADR of the previous 100 screening colonoscopies performed by the same endoscopist. A Cox-regression model and Kaplan-Meier survival analysis were used to explore the relationship between dynamic ADR and metachronous advanced colorectal neoplasia (ACRN).

RESULTS

Totally, 3471 individuals who had low-risk findings removed in baseline colonoscopy were included in analysis. Decreasing endoscopists' dynamic ADR was independently associated with metachronous ACRN. A 3.97-, 2.21-, and 2.67-fold increased risk for metachronous ACRN was observed in individuals of which baseline colonoscopy was performed by an endoscopist with a dynamic ADR of < 15%, 15-19%, and 20-24%, respectively, compared with those with the highest dynamic ADR (≥ 25%). The cumulative incidence of metachronous ACRN reached the 5% threshold at 4.5 years, 7.3 years, and 6.2 years in the dynamic ADR < 15%, 15-19%, and 20-24% group, respectively.

CONCLUSION

Endoscopists' dynamic ADR influences the risk of metachronous ACRN after removal of low-risk findings in screening colonoscopy. Individuals undergoing removal of low-risk findings in screening colonoscopy by an endoscopist with a dynamic ADR < 25% may benefit from a shorter duration of follow-up interval.

Value of 18F-FDG PET/CT in the diagnosis and grading of incidental colorectal adenomas

PURPOSE

Colorectal adenomas (CRAs) are at a higher risk of progressing to colorectal cancer (CRC) as their histological grade increases. Herein, this study investigated the relationship between the maximum standardized uptake value (SUVmax) on 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) and the histological grades of CRAs and constructed the optimal regression model for distinguishing between different histological grades.

METHODS

This study retrospectively analyzed the data of 153 patients with CRAs who had colorectal 18F-FDG uptake incidentally found on PET/CT. The patients were categorized into low-grade intraepithelial neoplasia (LGIN) and high-grade intraepithelial neoplasia (HGIN) groups based on their histological grade. After the analysis of the relationship between SUVmax measured on preoperative 18F-FDG PET/CT scans and histological grades, receiver-operating characteristic (ROC) curves were analyzed to determine the optimal cut-off values for distinguishing between the two groups. Common clinical and pathological factors were included and subjected to univariate and multivariate logistic regression analyses to identify independent risk factors. A diagnostic model integrating SUVmax and several risk factors was developed with the multivariate logistic regression analysis.

RESULTS

SUVmax was significantly different between the two groups (P < 0.001) and increased with an elevation in the malignancy degree. The area under the ROC curve (AUC) for identifying LGIN and HGIN was 0.796, and the AUC of the combination model was 0.822. Furthermore, SUVmax was an independent risk factor for distinguishing between different histological grades in pairwise comparisons.

CONCLUSION

The regression model involving SUVmax on 18F-FDG PET/CT can distinguish between histological grades of CRAs, which therefore can be used as a noninvasive tool for the accurate diagnosis of CRAs and assist in developing patient-specific treatment strategies before surgery.

Surveillance after colorectal polyp resection

Post-polypectomy surveillance has proven to reduce colorectal cancer (CRC) incidence in patients with high-risk polyps, but it implies a major burden on colonoscopy units. Therefore, it should be targeted to individuals with a higher risk. Different societies have published guidelines on surveillance after resection of polyps, with notable discrepancies among them, and many recommendations come from low-quality evidence based on surrogate measures, such as risk of advanced adenoma, and not CRC risk. In this review, we aimed to summarize the evidence supporting post-polypectomy surveillance, compare the recently updated major guidelines, and discuss the existing discrepancies on this topic. Briefly, patients with adenomas ≥10 mm or high-grade dysplasia and patients with serrated polyps ≥10 mm or dysplasia are generally considered to have an increased risk of metachronous CRC and require surveillance, whereas the indication of surveillance is not clearly established in patients without these high-risk features.

Identification of LncPVT1 and CircPVT1 as prognostic biomarkers in human colorectal polyps

LncPVT1 and CircPVT1 are isoforms for the PVT1 gene and are associated with cancer progression and carcinogenesis. Our study investigated the expression of LncPVT1 and CircPVT1 in colon adenoma polyps. 40 tissues of colorectal polyps and 40 normal-adjacent tissues (NATs) were taken. The expression of LncPVT1 and CircPVT1 was evaluated through qRael-Time PCR. The relation between expression and features of clinicopathological was explored. The ceRNA network was constructed by LncPVT1 and CircPVT1 and predicted miRNAs and miRNAs targets. Further, hub nodes in this network were determined using the cytoHubba package. Over-expressed LncPVT1 and CircPVT1 were differentiated in polyp and NATs. The expression level of LncPVT1 and CircPVT1 were significantly higher in adenoma polyps than in hyperplastic polyps. The area under the curve of the ROC estimate for the LncPVT1 and CircPVT1 was 0.74 and 0.77, respectively. A positive correlation was observed between the LncPVT1 expression and CircPVT1. Three miRNAs, including hsa-miR-484, hsa-miR-24-3p, hsa-miR-423-5p, and CircPVT1, were detected as ceRNA hub nodes. In this study, expression profiles of LncPVT1 and CircPVT1 were significantly higher in precancerous polyps. In addition, based on our in silico analysis, LncPVT1, CircPVT1/miR-484, miR-24-3p, miR-423-5p/PLAGL2 axis might be involved in colon cancer development. LncPVT1 and CircPVT1 can be prescribed as warning problems as potential prognostic biomarkers in patients with pre-CRC colon polyps.

Risk Factors for Metachronous Colorectal Cancer or Advanced Adenomas After Endoscopic Resection of High-risk Adenomas

BACKGROUND & AIMS

Among the characteristics of high-risk adenomas (HRAs), some may predict a higher risk of metachronous advanced lesions. Our aim was to assess which HRA characteristics are associated with high risk of metachronous colorectal cancer (CRC) or advanced adenomas (AAs).

METHODS

We systematically searched Pubmed, EMBASE, and Cochrane for cohort studies and clinical trials of CRC or AA incidence at surveillance stratified by baseline lesion size, histology, and multiplicity. We calculated pooled relative risks (RRs) using a random-effects model. Heterogeneity was assessed with the I² statistic.

RESULTS

Fifty-five studies were included, with 936,540 patients with mean follow-up 5.4 ± 2.9 years. CRC incidence per 1000 person-years was 2.6 (2.1-3.0) for adenomas ≥20 mm, 2.7 (2.2-3.2) for high-grade dysplasia (HGD), 2.0 (1.8-2.3) for villous component, 0.8 (0.1-1.4) for ≥5 adenomas, 1.0 (0.7-1.2) for ≥3 adenomas. Metachronous CRC risk was higher in adenomas ≥20 mm vs 10 to 19 mm (RR, 2.08; 95% confidence interval [CI], 1.20-3.61), HGD vs low-grade dysplasia (RR, 2.89; 95% CI, 1.88-4.44), villous vs tubular (RR, 1.75; 95% CI, 1.33-2.31). No significant differences in CRC risk were found in ≥3 adenomas vs 1 to 2 (RR, 1.24; 95% CI, 0.84-1.83), nor in ≥5 adenomas vs 3 to 4 (RR, 0.79; 95% CI, 0.30-2.11). Compared with normal colonoscopy, RR for CRC risk was 2.61 (95% CI, 2.06-3.32) for ≥10mm, 6.62 (95% CI, 4.60-9.52) for HGD, 3.58 (95% CI, 2.24-5.73) for villous component, and 2.03 (95% CI, 1.40-2.94) for ≥3 adenomas. Similar trends were seen for metachronous AAs.

CONCLUSION

Metachronous CRC risk is highest in patients with baseline adenomas with ≥20 mm or HGD. Multiplicity does not seem to be associated with substantially higher CRC risk in the near term.

Review article: obesity and colorectal cancer

BACKGROUND

Obesity is a growing global public health problem. More than half the European and North American population is overweight or obese. Colon and rectum cancers are still the second leading cause of cancer death worldwide, and epidemiological data support an association between obesity and colorectal cancers (CRCs).

AIM

To review the literature on CRC epidemiology in obese subjects, assessing the effects of obesity, including childhood or maternal obesity, on CRC, diagnosis, management, and prognosis, and discussing targeted prophylactic measures.

METHOD

We searched PubMed for obesity/overweight/metabolic syndrome and CRC. Other key words included 'staging', 'screening', 'treatment', 'weight loss', 'bariatric surgery' and 'chemotherapy'.

RESULTS

In Europe, about 11% of CRCs are attributed to overweight and obesity. Epidemiological data suggest that obesity is associated with a 30%-70% increased risk of colon cancer in men, the association being less consistent in women. Visceral fat or abdominal obesity seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m² increase in body mass index confers more risk (hazard ratio 1.03). Obesity might increase the likelihood of recurrence or mortality of the primary cancer and may affect initial management, including accurate staging. The risk maybe confounded by different factors, including lower adherence to organised CRC screening programmes. It is unclear whether bariatric surgery helps reduce rectal cancer risk.

CONCLUSIONS

Despite a growing body of evidence linking obesity to CRC, many questions remain unanswered, including whether we should screen patients with obesity earlier or propose prophylactic bariatric surgery for certain patients with obesity.