Argon plasma coagulation for successful treatment of early gastric cancer with intramucosal invasion

Abstract

Background: In recent years, there has been an increasing number of cases of early gastric cancer (T1, NX) with intramucosal invasion, which are untreatable by surgical or endoscopic mucosal resection (EMR) because of their high risk. Currently, no adequate treatment is available for such patients.

Aim: The main objective of this study was to evaluate whether argon plasma coagulation (APC) is an effective and safe modality for treating early gastric cancer untreatable by surgical resection or EMR.

Methods: The study group comprised 20 men and seven women diagnosed with gastric cancer with intramucosal invasion who were considered poor candidates for surgical resection or EMR due to risk factors such as severe cardiac failure or thrombocytopenia. Irradiation conditions for APC treatment were determined using swine gastric mucosa. We used an argon gas flow of 2 l/min at a power setting of 60 W and a maximum irradiation time of 15 s/cm(2). The follow up period of the 27 patients ranged from 18 to 49 months (median 30 months).

Results: All lesions were irradiated easily, including areas anatomically difficult for EMR such as the gastric cardia or the posterior wall of the upper gastric body. In 26 of 27 patients (96%) there was no evidence of recurrence during the follow up period (median 30 months). One patient showed recurrence six months after the treatment but was successfully retreated. No serious complications were found in any of the 27 patients but three patients (11%) experienced a feeling of abdominal fullness.

Interpretation: APC is a safe and effective modality for treatment of early gastric cancer with intramucosal invasion untreatable by surgical resection or EMR. However, further observations are necessary to determine the long term prognosis of patients undergoing this treatment.

Figure 1

Macroscopic findings of swine gastric mucosa irradiated by argon plasma coagulation (APC) under various conditions. The effect of APC was macroscopically studied on swine gastric samples at 20, 40, 60, 80, and 100 W, with pulse durations of 5, 10, 15, and 20 seconds. The mucosa exposed to a greater output power of high frequency current and/or for a longer pulse duration underwent more conspicuous colour change from white to brown.

Figure 2

Coagulation depth under various irradiation conditions based on histological analysis. The experiment was repeated twice using stomachs from two swine (Exp 1 and Exp 2). The coagulation front became deeper as the duration of irradiation was prolonged, reaching a plateau after irradiation for 15 seconds with each power setting. It was determined that the optimum argon plasma coagulation treatment conditions for clinical study were a current of 60 W and a maximum irradiation time of 15 s/cm², which would not be expected to cause perforation.

Figure 3

Histological features of swine gastric mucosa treated with argon plasma coagulation (APC) at a power setting of 60 W with various pulse durations. (A, B) Five seconds, 300 J/cm²; (C, D) 10 seconds, 600 J/cm²; (E, F) 15 seconds, 900 J/cm²; (G, H) 20 seconds, 1200 J/cm². Conventional haematoxylin-eosin (H&E) stain (A, C, E, G) and Elastica-Van Gieson stain (B, D, F, H) were performed. Irradiation for five seconds (300 J/cm²) caused necrosis of the upper mucosal layer and degenerative changes in the middle mucosal layer, so coagulation did in fact reach the middle mucosal layer (A). After 10 seconds (600 J/cm² ) of irradiation, coagulation reached the deep mucosal layer (C). No damage to submucosal collagen was identified by Elastica-Van Gieson stain after five seconds (B) or 10 seconds (D) of irradiation. The whole mucosa was coagulated after 15 seconds (900 J/cm²) of irradiation (E). Degenerative collagen was identified in the upper submucosal layer after 20 seconds (1200 J/cm²) of irradiation (F). Coagulation reached the middle part of the submucosal layer (G) but even at this depth the muscle layer showed no changes (H), suggesting no risk of perforation.

Figure 4

A case of early gastric cancer type IIc (depressed type): patient No 2 in table 1 ▶. Age/sex: 70 years/male. Location: antrum, anterior. Size: 10 mm in diameter. Type: IIc (depressed type); residual lesion of post endoscopic mucosal resection. Depth: intramucosal invasion. Pathology: well differentiated adenocarcinoma. Comorbid factors: myelodysplastic syndrome, cerebral infarction. (A) Before irradiation; (B) immediately after irradiation; (C) one week after irradiation; and (D) six months after irradiation.

Figure 5

Another case of early gastric cancer type IIc (depressed type): patient No 12 in table 1 ▶. Age/sex: 73 years/female. Location: upper body, posterior. Size: 18 mm in diameter. Type: IIc (depressed type) with ulcer formation. Depth: intramucosal invasion. Pathology: well differentiated adenocarcinoma. Comorbid factors: myocardial infarction, cerebral infarction (A, B) Before irradiation; and (C) three weeks after irradiation.