One of the most frequent localization of polypoid formations of the mucous membrane is the colon, while this pathology is of particular importance in terms of the risk of developing colorectal cancer. Among the most common variants are hyperplastic polyps, adenomas and dentate formations [1]. The prevalence of hyperplastic polyps in colonoscopic examinations usually ranges from 10% to 15%, but in certain population groups it can reach 30% [2]. A meta- analysis of screening colonoscopic examinations at the age of ≥50 years showed that the overall prevalence of adenoma is approximately 24%, and the frequency of detection of advanced forms of polyps (size ≥10 mm, villous adenomas, and high degree dysplasia) was about 4.5% [3]. The prevalence of traditional dentate colon adenomas (average size about 15 mm) is less than 1% during screening colonoscopy [4]. At the same time, colorectal cancer remains the second leading cause of cancer mortality worldwide, with a lifetime risk of developing from about 4% to 5% [5]. Screening for colorectal cancer and removal of precancerous colon adenomas leads to a decrease in morbidity and mortality by about 50% [6]. Most colorectal polyps are small, benign formations, however, in 10-15% of cases, polyps are classified as "complex", that is, which are technically difficult for endoscopic resection due to their size (> 20 mm), morphology or localization (ileocecal valve, appendicular opening, dentate line) [7, 8].

Most of the recommendations are aimed at removing polypoid formations larger than 5 mm [9]. A biopsy cannot completely exclude dysplasia and malignancy, therefore, after complete removal of the formation, a thorough pathological examination with morphological verification and assessment of the quality of resection should be carried out [10]. The detection of precancerous colon polyps is a global problem, since the risk of developing colorectal cancer during life remains from about 4% to 5% [11]. Treatment methods for polypoid formations include clipping, cold excision, electrocoagulation, endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), etc. [12]. The probability of complete removal of polyps depends on their size and the method of excision, in particular, with a diameter of 6-20 mm, this indicator reaches 81.6% with cold removal and 94.1-95.5% with cold or thermal resection [13]. According to other data, the frequency of single block resections ranges from 44.5 to 63% for EMR and from 87.9% to 96% for ESD [14]. Endoscopic submucosal dissection has a higher level of complete resection than other options, but at the same time the risk of bleeding and perforation increases [15].

Proper diagnosis and reduction of the risk of these interventions are of key importance in the endoscopic treatment of superficial formations of the gastrointestinal tract [16]. The removal of such formations is associated with a considerable risk of complications and should be performed by specially trained endoscopists [17]. Bleeding and perforation are among the main complications that develop both during the intervention and in the early period [18].The frequency of early post manipulation bleeding ranges from 0% to 6.3%, perforations 0-6% [19]. Conducting an intervention in the colorectal area is technically more difficult than in the upper gastrointestinal tract, which is reflected in a higher probability of complications and recurrence of polyps [20]. The recurrence rate of polyps can reach 32.1% [21-22]. Even after complete resection by endoscopic resection or dissection, recurrences occur in 2.4-12.2% of patients due to incomplete removal [23-24]. Local recurrence after polyp resection occurs in 3% of cases with single block removal and in 20% with fragmentary resections [25]. There is still insufficient research to assess the advantages and disadvantages of various methods of polyp removal [26]. The issue of improving the effectiveness of endoscopic treatment of polypoid formations requires further study [27-29]. This applies both to the correct choice of endoscopic methods and methods of removing formations [18].

The material for the analysis of clinical studies was the evaluation of the results of treatment of patients with superficial neoplastic lesions of the colon. This group included patients with superficial formations in the colon, 112 patients in the comparison group (170 formations were removed) and 96 patients in the main group (152 formations were removed). There were 75 patients with single formations in the comparison group, 60 in themain group, 2 formations in 22 and 21 patients, respectively, 3 formations in 12 and 13 and more than 3 in 3 and 2. The average size in the comparison group was 1.8 cm, in the main group 1.9 cm.

In 42 cases, polypoid formations of type 0-Is were removed in the comparison group and 39 in the main group. Non-polypoid slightly raised surface formations (0-IIa) were removed in 125 and 109 cases, respectively. Also, after the introduction of the submucosal dissection method, 3 LST- type formations (laterally spreading formation) were removed in the comparison group, there were 4 such formations in the main group.

Endoscopic interventions in the comparison group included cold removal with biopsy forceps – 16 formations, cold removal with a loop – 34, thermal removal by electro excision – 58, EMR – 43 cases and ESD – 19. In the main group, a new method of endoscopic excision was used, while thermal removal by laser excision was performed in 72 cases, EMR – 48 and ESD – 32 cases.

The main technical aspects of the method include the introduction of a gel prepared from Hemoben powder and 20 ml of methylene blue solution into the submucosal layer in the area of the base of the polyp with the formation of a roller. Next, the polyp is excised along with the surrounding healthy tissue of the mucous membrane to the submucosal layer by using a diode laser of the Gbox system (Figure. 1). It should be noted that in the absence of high-energy laser equipment, the use of injection under the mucous membrane of the proposed composition of the gel composition can also be used with standard methods of cold or thermal excision.

Figure 1: Stages of performing removal of the sigmoid colon polyp.

The advantages of the method are the following factors: complete and stable hemostasis is achieved; the risk of damage to the musculoserous layer of the stomach is prevented, thereby reducing the risk of organ perforation; radical removal of the polyp is achieved regardless of the shape of its pedicle; a high-energy laser is used, which has less penetrating power compared with electrocoagulation, as well as Infrared laser.

In the comparison group, the proportion of excisions in a single block was 57.1% (with 97 out of 170 polyps), respectively, 73 (42.9%) polyps were removed from fragments. In the main group, taking into account the implementation of the new excision technique, this indicator was 70.4%- in a single block (with 107 out of 152 polyps) and 45 (29.6%)–fragmentally. With polyps up to 1 cm in the comparison group, 29 were removed in a single block, in the main group in 29 cases. With formations of more than 1cm in 52.7% and 66.1% of cases. When performing excisions, there were no signs of bleeding in 71 (41.8%) cases in the comparison group and in 108 (71.1%) interventions in the main group. Clinically significant manifestations of hemorrhagic syndrome during manipulation were in 4.7% of cases in the comparison group and none in the main group. In the early period after endoscopic excision, delayed bleeding after removal of polyps developed in 4 (2.4%) cases in the comparison group and only in 1 (0.7%) case in the main group. Of the 112 patients in the comparison group, in addition to delayed bleeding, 1 (0.9%) case of postpolypectomy electrocoagulation syndrome was also noted. There were 107 (95.5%) patients in the comparison group and 95 (99.0%) in the main group without any complications. In the comparison group, morphological verification was not possible in 39 cases in the material sent for histological examination, in the main group the proportion of morphologically unidentified variants of polyps was only 7.9%. Hyperplastic character was identified in 36.6% of cases in the comparison group and 32.9% in the main group. The most dangerous adenomatous type and dentate formations from the point of view of malignancy were identified in 48.9% and 14.5% of cases in the comparison group and 50.7% and 16.4% in the main group.

In contrast to the removed formations from the mucosa of the upper gastrointestinal tract, morphological examination of preparations from the colon revealed a different degree of dysplasia in 51.1% of cases in the comparison group and 56.4% in the main group. Malignancy was detected in 3 cases in the comparison group and 4 in the main group. Surgical treatment with established malignancy was performed only in 2 patients (right-sided hemocolonectomy), the remaining patients refrained from surgery and were observed in dynamics.

After removal of formations from the colon mucosa in the main group, 64 drugs were evaluated for the quality of the performed resection. During morphological analysis of the edges of the resected formations, the polyp tissue was verified in 20.3% of cases, which corresponded to R1 resection, and in 79.7% of cases, pathological tissue was not determined along the edge of resection (R0 resection). In polyps up to 2.0 cm, R0 resection was determined in 91.7% of cases, R1 resection in 8.3%. With polyps over 2.0 cm, resection of R0 was determined less frequently and amounted to 76.9%.

The reduction in the duration of the hospital period after removal of tumors in the colon in patients in the main group cannot be recognized only as a result of the introduction of a new method. It is also of objective importance to increase the experience of performing such manipulations, to expand the indications for simultaneous removal of several formations at once. In general, according to this indicator, after the introduction of the new technique, the hospital period after the intervention significantly decreased. Thus, 37 (33%) patients in the comparison group and 60 (62.5%) in the main group were discharged within 3 days. 64 (57.1%) and 34 (35.4%) patients were discharged within 4-5 days, respectively, 11 (9.8%) and 2 (2.1%) spent more than 5 days in the department (χ2=19.574; df =2; p<0,001).

The average bed day after endoscopic colon surgery was 4.0±1.2 days in the comparison group and 3.4±1.0 days in the main group (t=4.23; p<0.05).

Long-term results were observed in 91 patients in the comparison group and 80 in the main group. In the comparison group, no relapses were noted in 69 (75.8%) patients during the control study, however, in 22 (24.2%) cases, recurrences of the development of superficial neoplasms were verified. In the main group, relapse was detected in only 4 (5.0%) patients.

With polyps up to 1 cm in the comparison group, recurrence was determined at 3.8%, no recurrence was noted in the main group. With polyps 1-2 cm, the recurrence rate was 7.7% versus 0% (Table 1). With polyps over 2.0 cm, this value reached 20.4% in the comparison group, whereas in the main group it was only 4.5%.

Table 1: Recurrence of Neoplasm Development Depending on the Initial Size of the Formations (from the Number of Formations).

Also, in the comparison group, the proportion of recurrence from excision of polyps in a single block was 7.5%. In the main group of 90 formations removed by a single block, relapse was in 1 (1.1%) case. Fragmented deletion increased these figures to 24.6% and 7.0%. Summarizing all the results of treatment, the following can be noted. In our study, we considered the results to be good, which excluded the development of immediate complications after manipulation and recurrence of polyp formation. The results were considered satisfactory if there were no recurrence of pathology, but there were any clinically significant complications resolved conservatively (postpolypectomy electrocoagulation syndrome) or repeated endoscopic intervention (delayed bleeding) (grade 2-3a according to Clavien-Dindo). The results were considered unsatisfactory when relapses of neoplasm formation were noted in the long-term period (Figure. 2). Taking into account all patients initially included in the study, the proportion of good results in the main group increased from 57.1% (64 patients in the comparison group) to 78.1% (75 patients in the main group), satisfactory results were obtained in 4.5% (5) and 1.0% (1), unsatisfactory– 19.6% (22) and 4.2% (4) of patients, respectively, in another 18.8% (21) and 16.7% (16) of cases, the result was not evaluated due to the failure of patients to attend a control examination (-2=15.536; df=3; p=0.002).

 Figure 2: The Overall Result of Endoscopic Treatment, Taking Into Account the Patients Followed in the Near and Long-Term Period. 

If we consider the cohort of patients only tracked in the long–term period, the proportion of good results in the comparison group was 70.3% (in 64 of 91 patients), satisfactory– 5.5% (5) and unsatisfactory- 24.2% (22). In the main group, the results corresponded to good in 93.8% (in 75 out of 80 patients) cases, satisfactory in 1.3% (1) and unsatisfactory in 4 (5.0%) cases (χ2=15,355; df=2; p<0,001).

Endoscopic removal of superficial polypoid and non polypoid neoplasms of the colon mucosa according to the developed technique allowed to increase the probability of excision in a single block from 57.1% to 70.4% (p=0.014), significantly reduce the risk of hemorrhagic manifestations requiring additional manipulations both during the intervention (from 4.7% to 0%) and delayed bleeding in the next the period (from 2.4% to 0.7%) (p=0.012), as well as the overall over all complication rate from 4.5% to 1.0%, while the duration of the hospital period after the intervention decreased from 4.0±1.2 to 3.4±1.0 days (p<0.05).

The risk of recurrence after removal of superficial neoplasms from the colon depends on factors such as size, method of removal and localization, while the proposed technique allowed to reduce this indicator across the entire sample from 24.2% to 5.0% (p<0.001), when removed in a single block - from 7.5% to 1.1% (p=0.037), fragmented excision from 24.6% to 7.0% (p=0.019), the size of formations up to 1 cm from 3.8% to 0%, 1-2 cm – from 7.7% to 0%, more than 2 cm – from 20.4% to 4.5% (p=0.002), in turn, when the formations are removed In the right half of the colon, the recurrence rate of pathology decreased from 23.7% to 5.3% (p=0.005) and in the left part from 9.3% to 1.3% of cases (p=0.027).

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