Early gastric cancer is a malignant tumor confined to the mucosa or submucosa, with or without lymph node metastasis. Endoscopic submucosal dissection (ESD) is an advanced endoscopic technique developed at the end of the 1990s in Japan that enables en bloc resection, regardless of the size of the lesion.1,2Unlike mucosectomy, ESD makes en bloc resection possible, allowing better pathologic evaluation of the surgical specimen, a greater number of complete resections, and less premalignant and malignant local gastric lesions.3,4

Endoscopic therapy for early gastric cancer is indicated in carcinomas with close to 0% risk for lymph node metastasis. Initial studies determined that intramucosal differentiated carcinomas (cT1a) smaller than 2cm, that had no ulceration, met those criteria. Later studies found that the risk for lymph node metastasis was extremely low (under 1%) in the following lesions: 1) UL (-) cT1a differentiated carcinomas larger than 2cm in diameter, 2) UL (+) cT1a differentiated carcinomas smaller than 3cm in diameter, 3) UL (-) cT1a undifferentiated carcinomas smaller than 2cm in diameter, and 4) tumors smaller than 3cm involving the superficial submucosa with no lymphovascular infiltration (ly, v).5

The aim of the present study was to evaluate the feasibility of ESD and to determine the clinical and pathologic characteristics of early gastric cancers and premalignant lesions.

A descriptive, case series study was conducted within the time frame of January 2012 and January 2017 in Lima, Peru, at two centers: the Health Department's Hospital Arzobispo Loayza, which is a national referral center for gastroenterology, and the Clínica Anglo Americana. All lesions were previously diagnosed through endoscopy with biopsy. The clinical and pathologic characteristics evaluated were: sex, age, macroscopic tumor size and type, tumor location, procedure duration, en bloc resection, complications, depth of invasion, compromised lateral margins, and histologic type. Tumor location was divided into upper, middle, and lower, according to the Japanese classification of gastric cancer.

En bloc resection was defined as that which made it possible to obtain the endoscopic specimen in a single piece with no fragmentation. Complete resection was defined as the entire removal of the cancer, leaving no neoplastic components in the lateral or vertical margins and with no lymphovascular invasion in the microscopic examination and when en bloc adenocarcinoma resection was: (I) predominantly differentiated, intramucosal, with no ulcer, disease-free lateral and vertical margins, regardless of lesion diameter; (II) lesion < than 3cm, predominantly differentiated, intramucosal, and ulcerated; (III) lesion < 2cm, predominantly undifferentiated, intramucosal, and non-ulcerated; or (IV) lesion < 3cm, predominantly differentiated, up to submucosa 1 (less than 500 μm). Curative resection was considered when there was no lymphovascular invasion and lateral and vertical margins were lesion-free, according to expanded indications.5 Recurrence was defined as the reappearance of the cancer at the lesion site (local recurrence), synchronous or metachronous reappearance, or distant metastasis.

The endoscopes employed were: the standard FUJINON model EG-590WR endoscope with 0.4% of indigo carmine, and in some cases, the LASEREO model EG-L590Z magnification endoscope. Carbon dioxide instead of air was used in the procedures performed at the Clínica Anglo Americana. The ESD technique utilized consisted of the following steps: 1) marking the perimeter of the lesion; 2) submucosal injection to produce a submucosal buffering effect and to raise the lesion; 3) an incision outside of and surrounding the marked limits of the lesion; 4) submucosal dissection. In several cases, the surrounding incision was not initially complete, to maintain the tension of the specimen to be resected, and the submucosal dissection was progressively alternated with the incision. A model DH-11GZ transparent CAP was placed at the tip of the endoscope in the majority of cases. Isotonic saline solution and/or hyaluronic acid at 0.4% (Lagricel®) was injected to create a submucosal buffer. A small quantity of indigo carmine was mixed in all the solutions and injected with a 21 to 25-caliber needle. Circumferential incision and submucosal dissection were achieved with a variety of devices that included: a Hybrid knife-I, Flush knife BT-2, Hybrid knife T, and IT-knife-2. Immediate bleeding was that in which there was a descent in hemoglobin greater than 2 g/dl from the beginning of the procedure to 24 h after the procedure. Late bleeding was defined as clinical evidence of bleeding that required endoscopic treatment, such as hematemesis or melena, 0-30 days after the procedure.

The first case report of submucosal dissection of early gastric cancer in Peru was presented by Vargas et al.6 in 2012, with no others reported in the country since then.

The incidence of lymph node metastasis was studied by Gotoda et al., who analyzed more than 5,000 gastrectomies with D2 lymph node dissection. That study published both the absolute and expanded criteria for ESD of early gastric cancer lesions. According to those criteria, lymph node metastasis incidence is below 1%.7 In our study, 3 patients had submucosal invasion: one patient up to SM1 and 2 patients to SM2. In the patient with SM1, conservative treatment was decided upon, given that all the Godota criteria were met: well differentiated lesion smaller than 3cm (it measured 1.2cm in diameter and only 300μm in depth).

The importance of early gastric cancer diagnosis is that if the lesion is resected and meets the curative criteria defined by Oda et al.,45-year survival can be greater than 95%, similar to that for surgery.5 Fukunaga et al. demonstrated greater survival (97.1 vs 85.8%; p = 0.01) and fewer adverse effects (6.8 vs 28.4%; p < 0.01) in patients that underwent ESD, compared with those that had surgery in a study that evaluated follow-up at 5 years in patients with differentiated early gastric cancer according to the expanded criteria.8 The incidence of gastric cancer recurrence after submucosal dissection has been reported at 0-1%.9 In our population, curative resection (6 out of 8 patients diagnosed with adenocarcinoma) was 75%, which is close to that reported in the international literature. We believe that was due to the experience of the endoscopist in performing the procedure and the adequate patient selection which was carried out following the Godota criteria, as well as working in two well-equipped endoscopic centers with the necessary resources for resolving any immediate complication and a team skilled in performing advanced endoscopic therapy.

Serious complications of the ESD procedure are bleeding and perforation, and incidence of the latter is 0-5%. Oka et al. reported the incidence of perforation at 9.7%, when ESD was performed in cases of non-ulcerated lesions.10 In our study on 13 patients, there was only one perforation and it was not resolved endoscopically (7.6%). Despite having detected the defect during the procedure, endoscopic closure was not achieved, due to technical difficulties. The patient progressed favorably after the surgery.

Oka et al. described an incidence of bleeding of 22.6% for ulcerated lesions and 6.2% for non-ulcerated lesions. Likewise, lesion size and location were found to be risk factors for bleeding (lesions at the greater curvature tend to bleed more). In our experience, one third of the lesions were larger than 30mm, but bleeding was not reported. Most likely that was due to the fact that both study sites had the necessary equipment for stopping immediate bleeding, such as Coagrasper forceps and other instruments, as well as having strict intra-procedural hemodynamic monitoring. The majority of lesions were located in the lower third of the stomach (92.3%) and were non-ulcerated lesions (76.9%), which could have reduced the risk for bleeding.

Our study is important because it is the first published case series on patients from 2 centers in Lima, Peru (the Hospital Nacional of the Health Department [MINSA, the Spanish acronym] and a private clinic) that demonstrates the feasibility and efficacy of the endoscopic technique in a larger number of cases with tumors of different sizes and locations, as well as a complication rate that coincided with international experiences. One of the study's limitations was the reduced sample size and the short follow-up period. However, we believe it is relevant to communicate the advances made with this effective technique. More studies should be conducted to evaluate patient follow-up and assess disease recurrence.

In conclusion, ESD is an advanced endoscopic technique that enables early extraction of gastric cancer in a single specimen with no fragmentation, even in large or ulcerated lesions, favoring a lower rate of local disease recurrence and gastric cancer cure in selected cases. The procedure was performed at two centers in Lima and showed complete, curative, en bloc resection rates, together with complication rates similar to those reported in the international literature. Endoscopic submucosal dissection enables the reduction of surgery in selected patients with gastric cancer and paves the way for the detection of more cases of early gastric cancer through screening programs in Peru.

No financial support was received in relation to this study.

The authors declare that there is no conflict of interest.