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Revista do Colégio Brasileiro de Cirurgiões

Print version ISSN 0100-6991

Rev. Col. Bras. Cir. vol.40 no.5 Rio de Janeiro Sept./Oct. 2013 



Complementation by argon plasma coagulation after endoscopic piecemeal resection of large colorectal adenomas



Walton AlbuquerqueI; Vitor Nunes ArantesII; Luiz Gonzaga Vaz CoelhoIII; Carlos Alberto Freitas DiasIV; Paulo Roberto Savassi-Rocha, TCBC-MGV

ICoordinator, Digestive Endoscopy Service, Alfa Institute of Gastroenterology, Clinics Hospital, UFMG
IIAssociate Professor, Department of Surgery, Faculty of Medicine, UFMG
IIIProfessor, Department of Internal Medicine, Faculty of Medicine, UFMG
IVPost-graduate, Digestive Endoscopy, Alfa Institute of Gastroenterology, Clinics Hospital, UFMG
VProfessor, Department of Surgery, Faculty of Medicine, UFMG

Address correspondence to




OBJECTIVE: To evaluate the efficacy of complement by argon plasma coagulation to reduce the rate of residual or recurrent tumor after complete endoscopic piecemeal resection of large sessile colorectal adenomas.
METHODS: Inclusion criteria: patients with large sessile colorectal adenomas (e" 20 mm), without morphological signs of deep infiltration, submitted to complete endoscopic piecemeal resection studied with chromoendoscopy and magnification of images. Patients were randomized into two groups: group 1 - no additional procedure, and group 2 - complementation by argon plasma coagulation. follow-up colonoscopy was performed at three, six and 12 months postoperatively. We evaluated the rate of local recurrence or residual malignancy.
RESULTS: The study included 21 patients, eleven in group 1 and ten in group 2. There were two local recurrences or residual tumors in each group, detected at three months follow-up.
CONCLUSION: Complementation by argon plasma coagulation after apparent complete endoscopic piecemeal resection of large sessile colorectal adenomas does not seem to reduce the occurrence of residual adenomatous lesions or local recurrence.

Key words: Adenoma. Colorectal neoplasms. Endoscopy. Coagulation agents. Argon plasma coagulation.




Large sessile colorectal adenomas (> 20 mm) are an important clinical problem due to an increased risk of malignant transformation1. These lesions are often endoscopically resected into several fragments, a technique called endoscopic piecemeal mucosal resection (EPMR). The disadvantage of this approach is the high rate of local recurrence or residual adenoma, present in up to 55% of cases2-16. Soon after the EPMR, particularly when small foci of residual lesions at the site of resection are identified, the additional application of argon plasma coagulation (APC) appears to reduce local recurrence5,11. However, after the considered complete EPMR, the actual value of the routine APC in terms of improvement of outcomes is yet to be demonstrated.

The aim of our study was to evaluate the effectiveness of complementation by argon plasma coagulation to reduce the rate of residual or recurrent tumor after complete endoscopic piecemeal resection of large sessile colorectal adenomas



Patients aged over 18 years with sessile colorectal adenomas > 20mm were referred for endoscopic treatment. Those who agreed to participate signed an informed consent and were included in the investigation. Lesions with malignant aspect at morphology and chromoendoscopy with images magnification (firm, ulcerated, friable, pit pattern – Vi or Vn) or considered technically impossible to be completely resected due to size or difficult position, were excluded. The flowchart of the patients studied is shown in figure 1.



The study was approved by the Ethics in Research Committee and of the institution (ETIC No. 019 / 04).

Endoscopic technique

Endoscopic procedures were performed with the same colonoscope by two experienced operators. The following protocol was used in all cases: after the identification of the lesion and removal of mucus with water and washing with N-acetylcysteine application, a detailed examination was carried out with white light followed by instillation of 0.4% indigo carmine for chromoendoscopy and magnification of images. Tumors were classified according to their morphology (Classification of Paris)17 and to the pit pattern (Kudo classification)18. Small coagulation marks were made around the lesion with two millimeters apart. Submucosal injection of 0.4% hydroxypropyl methylcellulose was performed to provide an adequate and prolonged elevation of the lesion19. Initially, we used hexagonal or oval, wide polypectomy loops, with application of a pure cut current (35 Watts), seizing large fragments, followed by resection of any small residual areas with miniloops until all adenomatous lesions were completely removed. We then repeated chromoendoscopy with magnification of images to check for residual lesions and, if present, had them totally removed.

After agreement by two expert examiners that the entire lesion had been removed, we removed four fragments of tissue from the specimen's resection margin, one from each quadrant. Patients were randomized into two groups: Group 1 - no additional procedure beyond mucosectomy; and Group 2 - application of APC on all surrounding edges, with coagulation effect of 60 Watts and output flow of 2.0L/min. Coagulation was considered sufficient when the tissue acquired a white color, proper of the coagulated area. The specimens' fragments were fixed in 10% formalin and embedded in paraffin. The slides were evaluated by an expert gastrointestinal pathologist and the results presented in accordance with the Vienna Classification20. If the histological examination revealed adenocarcinoma invading the submucosa, patients would be referred for surgical evaluation. Follow-up colonoscopies were performed at three, six and 12 months postoperatively. The site of resection was evaluated with chromoendoscopy with 0.4% indigo carmine and magnification of images, followed by biopsy of the scars. Should residual or recurrent lesions be detected, a new endoscopic treatment was performed.



During the study period, a total of 25 patients with 27 large sessile colorectal adenomas were referred to our center for endoscopic treatment. Five patients were excluded because of: overly large size of the lesion (n=3), aspect of deep infiltration (n=1) and association with prostate cancer infiltrating the rectum (n=1). Tables 1 and 2 describe the demographic characteristics and morphological classification of lesions in groups 1 and 2, respectively. There was no difference between the groups with regards to age, gender distribution, average size of tumors and their location.

Among the included patients, there were ten in group 1 (3 males and 7 females, total of 11 lesions), with a mean age of 67.1 years (range 54-77) and ten in group 2 (4 males and 6 females, total of ten lesions), with a mean age of 66.2 years (range 36-80). One patient had two lesions and therefore was randomized twice, both to Group 1. The results of the histological examination of the resection margins taken after the EPMR were all negative for adenomas. Two patients in group 2 had bleeding during the procedures, successfully treated by injection of adrenaline or hemostasis with metallic clips, without operation or blood transfusion. There were no other adverse events.

Residual/recurrent lesions

Two residual/recurrent lesions were detected in each group at three-months follow-up colonoscopy. In group 1 (without APC), the lesion occurred in a patient having a 30mm, 0-Is + 0-IIa lesion located in the descending colon and the other in an individual with a previous 40mm, 0-IIa lesion in the cecum. In group 2 (APC), the resected lesion was 60mm, 0-IIa, located in the rectum and the other was a 50mm, 0-Is +0-IIa adenoma in the ascending colon. In all cases, the number of resected fragments was > 4.

Among these four patients with residual/recurrent lesions, two in each group, three underwent new endoscopic resection with complementation with APC. They all remained tumor-free at six and 12 months follow-up. A lesion in group 1, located in the descending colon, with 30mm size, morphology 0-Is + 0-IIa, pits IIIL, of villous component, removed in four fragments, was referred for surgical resection because adenocarcinoma invading the submucosa was detected by histopathology.



The endoscopic management of large superficial sessile colorectal neoplasms recently evolved to en bloc resection by endoscopic submucosal dissection (ESD). The reported benefits of ESD over EPMR are the lower rate of residual or recurrent lesions and a better quality of the specimen for appropriate histological evaluation21.

The ESD is technically difficult and time consuming and requires a long learning curve, in particular for resection of large colonic adenomas. Therefore, EPMR is still widely practiced, at least in Western institutions. The addition of APC application in the site the EPMR is an attractive tool for the treatment of visible residual adenoma due to its simplicity, safety and efficacy5,6,11,22.

Only one randomized controlled study has addressed the role of the APC after the EPMR of large sessile colorectal adenomas, when the resection site presented with an aspect "clean" of neoplastic lesions. This study showed a decrease of residual or recurrent adenomas in the group treated with APC23.

In this study, complete resection was considered when there was no visible residual lesions, both in the margins and in the central area of resection, as assessed by chromoendoscopy with indigo carmine and magnification of images, as proposed by Hurlstone et al.24. Among the 20 patients included in this study, four had in residual / recurrent lesions, two in each group, indicating that in this population the use of complementary APC did not affect the rate of residual adenomas after EPMR.

A complete analysis of the patients with residual / recurrent lesions showed that the tumor size was 30 and 40mm in group 1 and 50 and 60mm in group 2, and in all of them the amount of resected fragments was greater than four with histology of high-grade dysplasia. Our data suggest that in patients with these characteristics treated with EPMR, with or without additional APC, the expected rate of residual / recurrent lesion is at least 20%.

It is possible that some area of diminutive adenomatous lesion has not been recognized by chromoendoscopy with magnification image due to clotting artifacts and therefore APC was not properly applied. Another possibility is that, due to a small number of cases, our study lacked statistical power to detect a difference in the recurrence rate of adenomas treated with EPMR with or without APC.

In conclusion, in patients with sessile colorectal adenomas > 20mm, the routine application of additional APC after complete resection of the lesion by EPMR does not appear to decrease the rate of local residual or recurrent lesions. Our results suggest that lesions larger than 30 mm, resected in over four fragments with high-grade dysplasia, have a recurrence rate of 20% after EPMR. Further studies with a larger number of patients should be made for a more definitive conclusion.



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Address correspondence to:
Walton Albuquerque


Received on 03/09/2012
Accepted for publication 07/11/2012
Conflict of interest: none
Source of funding: FAPEMIG



Work Performed at the Alfa Institute of Gastroenterology of the Clinics Hospital of the Federal University of Minas Gerais – UFMG, Belo Horizonte, Minas Gerais State – MG, Brazil.

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