Safety of endoscopic mucosal resection (EMR) of large non-pedunculated colorectal adenomas in the elderly

BACKGROUND

Endoscopic mucosal resection (EMR) has been proven to be safe and effective for the treatment of colorectal adenomas. However, data are limited on the safety of this technique for large polyps and in elderly patients. Aims of our study were to examine the bleeding and perforation rates in patients with large non-pedunculated adenomas (≥20mm) and to evaluate the influence of size (≥40mm) and age (≥75 years) on the complication rates.

METHODS

In this multicenter retrospective study, patients who underwent EMR of non-pedunculated adenomas ≥20mm between January 2012 and March 2016 were included. The demographics of the patients, the use of antithrombotic drugs, size of the polyps, type of resection, pathology report, occurrence of post-polypectomy bleeding, and perforation- and recurrence rate were collected.

RESULTS

In 343 patients, 412 adenomas were removed. Eighty patients (23.3%) were ≥75 years of age, 138 polyps (33.5%) were ≥40mm. Bleeding complications were observed in 28 cases (6.8%) and were found significantly more frequent in adenomas ≥40mm, independent of the use of antithrombotic therapy. Five perforations (1.2%) were described, not related to the size of the polyp. There was no significant difference in complication rates between patients <75 years and patients ≥75 years. Bleeding complications rates were significantly higher in patients receiving double antithrombotic therapy.

CONCLUSION

EMR is safe in elderly patients. EMR of adenomas of ≥40mm was associated with more bleeding complications. Future studies should address how the bleeding rates can be reduced in these patients, especially in those who use double antithrombotic treatment.

Morphometry of interstitial fibrosis

Several clinical studies have confirmed that histomorphometric changes in the tubulointerstitial compartment contain the best correlating parameters to predict the development of progressive renal insufficiency. The process of interstitial fibrosis is accompanied by an influx of inflammatory cells, up-regulation of fibrogenic cytokines such as transforming growth factor-beta and basic fibroblast growth factor, transient down-modulation of their antagonists, generation and proliferation of myofibroblasts, and, finally, by accumulation of interstitial collagens and proteoglycans. A careful morphometric analysis of interstitial fibrosis requires sensitive parameters through which the severity can be quantified and by which the progression into renal insufficiency can be predicted. We have addressed these issues by morphometric analysis of both human biopsies and by refining existing experimental models in the rat. Morphometric analysis was performed using a Zeiss microscope equipped with a full colour 3CCD camera and KS-400 image analysis software from Zeiss-Kontron. For studies with human material, biopsies were examined from patients with various renal diseases including patients with chronic allotransplant dysfunction. The development of interstitial fibrosis was correlated with clinical parameters. In experimental models, we analysed the interstitial composition and eventual glomerular alterations in rats with bovine serum albumin (BSA)-induced protein overload nephropathy and with human IgG-induced chronic serum sickness nephritis. Finally, we adapted and refined the model of ureter obstruction-induced interstitial fibrosis in the rat. For this purpose, custom-made titanium clips (S&T, Neuhaus, Switzerland) were implanted around the ureter in the abdomen of rats to obstruct the ureter without causing necrosis. The clips were removed at various time points after obstruction of the ureter (1-14 days). The subsequent remodelling of the interstitium was studied thereafter, in order to establish whether uraemia-induced interstitial fibrosis remains reversible at all times. In rat models, we have found that both protein overload-induced and serum sickness-induced interstitial fibrosis are accompanied by the development of focal and segmental glomerulosclerosis. Only in the ureter obstruction model did selective interstitial fibrosis develop, and remained reversible at all times studied. For the reliable assessment of interstitial fibrosis we have found that the best correlating parameters of interstitial fibrosis with renal function were: (i) the ratio of protein accumulation of TGF-beta-1 and its antagonist decorin; (ii) interstitial expression of smooth muscle alpha-actin; and (iii) accumulation of interstitial collagens (as determined by immunoperoxidase and by Sirius red staining).