Characteristics of metachronous gastric tumors after endoscopic submucosal dissection for gastric intraepithelial neoplasms. Gastroenterol Res Pract. 2014;2014:863595. [PMID: 24672541 PMCID: PMC3942338 DOI: 10.1155/2014/863595]

Metachronous gastric neoplasm beyond 5 years after endoscopic resection for early gastric cancer

BACKGROUND AND AIMS

The natural course of early gastric cancer (EGC) following endoscopic submucosal dissection (ESD) remains unclear. This study aimed to clarify the long-term clinical outcomes and risk factors of metachronous gastric neoplasm (MGN) 5 years after ESD for EGC.

METHODS

We performed a retrospective analysis of patients who underwent ESD for EGC from July 2005 to October 2015 in Seoul National University Hospital. Long-term clinical outcomes and risk factors of MGN after 5 years post-ESD were evaluated.

RESULTS

Among the 2059 patients who underwent ESD for EGC, 1102 were followed up for > 5 years. MGN developed in 132 patients 5 years after ESD. During the median follow-up period of 85 months, the cumulative incidences of MGN and metachronous gastric cancer were 11.7, 16.9, and 27.0 and 7.6, 10.8, and 18.7% after 5, 7, and 10 years, respectively. In multivariable analysis, male sex (odds ratio 1.770; P = 0.042), severe intestinal metaplasia (odds ratio 1.255; P = 0.000), tumor-positive lateral margin (odds ratio 2.711; P = 0.008), < 5 mm lateral safety margin (odds ratio 1.568; P = 0.050), and synchronous adenoma (odds ratio 2.612; P = 0.001) were positive predictive factors, and successful eradication of Helicobacter pylori (odds ratio 0.514; P = 0.024) was a negative predictive factor for MGN after 5 years post-ESD.

CONCLUSION

The cumulative MGN incidence was high even 5 years post-ESD for EGC. Meticulous long-term endoscopic follow-up is mandatory, especially in male patients with underlying intestinal metaplasia, tumor-positive lateral margins, lateral safety margins of < 5 mm, and synchronous adenomas.

Molecular subtype switching in early-stage gastric cancers with multiple occurrences

BACKGROUND

Multiple gastric cancers at the same time (synchronous) or recurrence after 1 year (metachronous) are frequently encountered. Since their genetic profiles were not well elucidated, we molecularly subtyped the genetic events of synchronous and metachronous early-stage gastric cancers.

METHODS

We studied mismatch repair (MMR) genes in 84 tumors from 31 patients (15 synchronous and 16 metachronous) by immunohistochemistry. We performed microsatellite instability analysis and targeted sequencing of 58 significantly mutated genes (SMGs) in 35 tumors from thirteen patients. Genomic data from TCGA were used for comparisons with advanced-stage cancers.

RESULTS

Among the 31 patients, at least one deficient-MMR (dMMR) tumor was observed in eight (26%). Of eight patients, seven showed a mixture of proficient-MMR (pMMR) and dMMR tumors. The one case with only dMMR had six recurrent tumors within 2 years. To further subtype, we sequenced 58 SMGs in 35 samples (25 pMMR and 10 dMMR) from thirteen patients. In 35 samples, 163 mutations were identified, but none matched in almost cases, strongly indicating different clonal origins, whether synchronous or metachronous occurrences. Of the 25 pMMR cases, 1 belonged to Epstein-Barr virus (EBV), 24 belonged to chromosomal instability (CIN) subtypes. Of the thirteen cases, repetitive CIN, a mixture of CIN and MSI, a mixture of CIN and EBV, and repetitive MSI were observed in nine (70%), two (15%), one (8%) and one (8%), respectively.

CONCLUSIONS

Despite multiple tumors occurring in the same patient simultaneously or several years apart, clonal origin was totally different. 'Switching' or 'mixing' of dMMR and pMMR, EBV or CIN occurred, which had clinical relevance with regard to immunotherapy.

Risk factors for early metachronous tumor development after endoscopic resection for early gastric cancer

BACKGROUND

Metachronous gastric tumor (MGT) is one of major concerns after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Optimal follow-up strategy has not been yet well-established. The aim of this study was to identify the different clinical features of the patients according to the time interval to development of MGT.

METHODS

Among 1,780 consecutive patients with EGC who underwent ESD between 2005 and 2014, 115 patients with MGT were retrospectively reviewed. MGT was defined as secondary gastric cancer or dysplasia detected > 1 year after initial ESD. Clinicopathological factors associated with early development of MGT were evaluated.

RESULTS

The median interval to development of MGT was 37 months. In univariate analysis, the median interval to MGT was shorter if EGC lesion was non-elevated type (39.4 vs 57.0 months, p = 0.011), or synchronous primary lesion was absent (39.8 vs 51.4 months, p = 0.050). In multivariate Cox's proportional hazards analysis, the hazard ratios for early occurrence of MGT were 1.966 (95% CI: 1.141-3.386, p = 0.015) and 1.911 (95% CI: 1.163-3.141, p = 0.011), respectively. There was no significant difference in overall survival after diagnosis of MGT between the early occurrence group and the late occurrence group.

CONCLUSIONS

Non-elevated gross type and absence of synchronous gastric tumor were independent risk factors for early development of MGT. Meticulous endoscopic inspection is especially important for the detection of MGT during the early follow-up period in patients with these initial tumor characteristics.

Comparing Laparoscopic to Endoscopic Resections for Early Gastric Cancer in a High Volume North American Center

Endoscopic submucosal dissection as an organ sparing option for early gastric cancer is becoming increasingly accepted as an alternative to laparoscopic gastrectomy. Given the very limited North American data, we sought to compare outcomes between endoscopic and laparoscopic resection of gastric malignant and premalignant tumors. Patients undergoing laparoscopic gastrectomy or endoscopic submucosal dissection from 2007 to 2014 for adenocarcinoma or dysplasia at the McGill University Health Center were identified from a prospectively collected database and dichotomized according to the surgical approach. Patient demographics, tumor characteristics, stage, oncologic outcome, length of stay, and postoperative complications were recorded. Of 155 patients with gastric cancer identified, 67 were treated by laparoscopic gastrectomy (n = 37) or endoscopic submucosal dissection (ESD) (n = 30). There were significantly more invasive lesions in the laparoscopic group and patients subject to ESD harbored more T1 lesions. No significant difference in the rate of R0 resection or overall complications was observed between the groups. Accordingly, length of stay was significantly shorter in the ESD group. There were no significant differences in terms of overall and disease-free survival. In selected patients, ESD is associated with improved short-term outcomes and provides an appropriate oncologic resection option in a North American patient cohort.

Endoscopic surveillance of gastric cancers after Helicobacter pylori eradication

The incidence and mortality of gastric cancer remains high in East Asian countries. Current data suggest that Helicobacter pylori (H. pylori) eradication might be more effective for preventing gastric cancer in young people before they develop atrophic gastritis and intestinal metaplasia. However, the long-term effect of H. pylori eradication on metachronous cancer prevention after endoscopic resection (ER) of early gastric cancer remains controversial, with some discordance between results published for Japanese and Korean studies. The detection ability of synchronous lesions before ER and eradication of H. pylori directly influences these results. After eradication, some gastric cancers are more difficult to diagnose by endoscopy because of morphologic changes that lead to a flat or depressed appearance. Narrow-band imaging with magnifying endoscopy (NBI-ME) is expected to be useful for identifying metachronous cancers. However, some gastric cancers after eradication show a "gastritis-like" appearance under NBI-ME. The gastritis-like appearance correlates with the histological surface differentiation of the cancer tubules and superficial non-neoplastic epithelium atop or interspersed with the cancer. Till date, it remains unclear whether H. pylori eradication could prevent progression of gastric cancer. Until we can establish more useful endoscopic examination methodologies, regular endoscopic surveillance of high-risk groups is expected to be the most beneficial approach for detection.

Endoscopic full-thickness resection for gastric submucosal tumors arising from the muscularis propria layer

AIM: To evaluate the efficacy, safety and feasibility of endoscopic full-thickness resection (EFR) for the treatment of gastric submucosal tumors (SMTs) arising from the muscularis propria.

METHODS: A total of 35 gastric SMTs arising from the muscularis propria layer were resected by EFR between January 2010 and September 2013. EFR consists of five major steps: injecting normal saline into the submucosa; pre-cutting the mucosal and submucosal layers around the lesion; making a circumferential incision as deep as the muscularis propria around the lesion using endoscopic submucosal dissection and an incision into the serosal layer around the lesion with a Hook knife; a full-thickness resection of the tumor, including the serosal layer with a Hook or IT knife; and closing the gastric wall with metallic clips.

RESULTS: Of the 35 gastric SMTs, 14 were located at the fundus, and 21 at the corpus. EFR removed all of the SMTs successfully, and the complete resection rate was 100%. The mean operation time was 90 min (60-155 min), the mean hospitalization time was 6.0 d (4-10 d), and the mean tumor size was 2.8 cm (2.0-4.5 cm). Pathological examination confirmed the presence of gastric stromal tumors in 25 patients, leiomyomas in 7 and gastric autonomous nerve tumors in 2. No gastric bleeding, peritonitis or abdominal abscess occurred after EFR. Postoperative contrast roentgenography on the third day detected no contrast extravasation into the abdominal cavity. The mean follow-up period was 6 mo, with no lesion residue or recurrence noted.

CONCLUSION: EFR is efficacious, safe and minimally invasive for patients with gastric SMTs arising from the muscularis propria layer. This technique is able to resect deep gastric lesions while providing precise pathological information about the lesion. With the development of EFR, the indications of endoscopic resection might be extended.