The trends in the management of EGC are different between Japan and the West.
European surgeons have been employing more aggressive surgery for curable gastric cancer. Japanese surgeons have been adopting more conservative methods ( endoscopic mucosal resection or functioning- preserving gastrectomies).
It depends on different treatment experiences and diagnostic techniques (Sano).
Endoscopic mucosal resection is a new technique for the treatment of early gastric cancer. The most common modalities include strip biopsy, double snare polypectomy, and resection with combined use of highly concentrated saline and epinephrine, and resection using a cap.
The indications are limited to differentiated IIa type (the slightly elevated type) that is smaller than 2 cm, or the differentiated IIc type (slightly depressed type) without ulcer formation or scar and smaller than 1 cm. The risk of lymph node metastasis for these entities is negligible.
Local recurrence is an eventuality and it depends on incomplete resection.
This can occur in lesions larger than 2 cm in size, depressed type lesions, and lesions located in areas that are anatomically difficult to access (the gastric angle, lesser curvature of the corpus, posterior wall or fundus).
Repeated resections after a certain interval are recommended if the surgical margin is too near the tumor in the first resection. More than 2 mm of cancer clearance in the specimen is necessary to reduce recurrence.
EMR is superior to methods involving tissue destruction, in terms of local recurrence, because it permits an accurate pathological evaluation of the resected specimen.
After a discovery of local recurrence the option is not only surgical resection, for local recurrence within the mucosal layer EMR is recommended if it satisfies the above criteria.
In fact multifocal lesions, either synchronous or metachronous are not uncommon in the stomach (Makuuchi ).
According to various reports multiple EGC accounts for 8,3% to 13,3% of all EGCs. Patients at risk for multicentricity of EGC are male, over 60 years of age, depressed type of well differentiated adenocarcinoma. Therefore it is advisable a careful preoperative examination in this cases.
Because the frequency of lymph node metastasis and the grade of vascular invasion in cases of multiple EGCs is equal than those in cases of solitary cancer, endoscopic treatment or limited surgery can be indicated for multiple EGCs. The unique condition is that each lesion of the multiple cancer fits the criteria for the application of the limited surgery (Takeshita).
Obviously it is mandatory not only the preoperative exclusion of accessory lesions but the close long-term follow up ( Holscher).
The main complications are postoperative bleeding and perforation of the gastric wall. In general bleeding is discovered several days after EMR, thereafter it is important to administer proton pump inhibitors with sodium alginate or H2-blockers for the prevention of post-EMR hemorrage.
Some authors try to widen the indications for EMR including 1)horizontally wider lesions longer than 2 cm in size; 2)small lesions that have invaded the shallow layer of the submucosa; 3) small lesions of signet ring cell carcinoma or poorly differentiated carcinoma, if the lesions are less than 0,5 cm in size.
EMR also is useful for local resection in elderly patients with various complications, who would be at risk for conventional surgical operations. (Makuuchi ).
Miyata highlights that the complete resection rate of EMR for EGC, without residual or recurrent lesions, is somewhat lower than that of surgical resection.
Multivariate analysis shows that EMR for cancer lesions of over 15 mm in size, and divided resection (two or more pieces) tends to be incomplete; poorly differentiated adenocarcinoma should not be resected endoscopically.
Therefore we can submit to EMR EGCs that are thought to be intramucosal differentiated adenocarcinomas without ulceration or scarring and no more than 15 mm in size regardless of the macroscopic form. EMR must be, in principle, performed en bloc, but not as divided resection. It is recommended a follow up endoscopic examination every 6 months for at least 5 years (Miyata).
Obviously EMR can be considered potentially curative if the primary tumor is completely removed with clear margin and the possibility of lymph node metastasis is zero or extremely low. Therefore it is necessary to wait for the histological examination of the resected specimen.
Furthermore lesions that are diagnosed as dysplasia in the West and carcinoma in Japan are generally removed by EMR (Sano).
Other conservative methods include modified gastrectomies for EGCs, with the aim of preserving the function of the stomach.
Seto describes a local resection with lymphadenectomy for mucosal early gastric cancers of 4cm in diameter or less, to prevent postgastrectomy syndrome.
The extent of lymphadenectomy depends on tumor location.
Intraoperative endoscopy and frozen section analysis of the dissected nodes determine the resection line and nodal status. In fact the tumor is excised with a non cancerous rime of 2 cm. If nodal involvement is detected by frozen section analysis, conventional gastrectomy with extended lymphadenectomy is mandatory.
It is important to preserve the pacemaker zone in the proximal corpus along the greater curvature and the preservation of the celiac, hepatic and pyloric branches of the vagus nerve.
Moreover it is recommended a long follow up to discover matachronous gastric cancer.
And finally a third problem is the revelation of the submucosal cancer invasion, that may be predicted by the report of a palpable tumor and /or macroscopic node involvement
(Seto).
A segmental gastrectomy for mucosal tumor in the mid-gastric body with preservation of the Latarjet branch of the vagal nerve and the hepatic and pyloric branches is mentioned by others.
Lymphadenectomy is limited to the perigastric regions close to the resected segment and for the lesser curve tumors the nodes along the left gastric arteries can be dissected (Furukawa).
Oghami suggests two laparoscopic techniques : the laparoscopic wedge resection of the stomach using a lesion-lifting method for lesions of the anterior wall, the lesser curvature and the greater curvature. And the laparoscopic intragastric mucosal resection for lesions of the posterior wall of the stomach and near the cardia or the pylorus.
The indications are: preoperative diagnosed mucosal cancer, <25 mm diameter elevated lesions; and <15 mm diameter depressed lesions without ulcer formation.
These are minimally invasive methods, they permit a detailed histological examination with a sufficient surgical margin horizontally and vertically, preserving most of the stomach.
According to the author's opinion laparoscopic surgery is preferable over EMR for the treatment of mucosal gastric cancer if the size of the cancer is more than 10 mm, or the site of the tumor is near the cardia.
Obviously a follow up period is recommended to discover recurrences or metachronous cancers
(Oghami).
For EGC in the proximal third of the stomach proximal gastrectomy with jejunal pouch interposition has been tested with or without preservation of the vagal nerve.
Takeshita describes a limited surgery for the treatment of EGC located in the upper third of the stomach based on a well balanced reduction in the extent of lymph node dissection and gastric resection (Takeshita).
In the pylorus preserving gastrectomy a pyloric cuff of 2 cm is preserved while the distal two thirds of the stomach is removed.
The regional node except the suprapyloric nodes are dissected. Moreover it is important the preservation of the hepatic and pyloric branches of the vagal nerve.
It is indicated for the EGC in the middle stomach, that gives metastasis to n 5 station rarely.
The advantage is a decreased incidence of postgastrectomy dumping syndrome and gallbladder stone formation, while the weight recovery is better than Billroth I reconstruction. Sometimes an emptying disturbance is present (Imada).
Tomita affirms that a postgastrectomy symptom, "gastric fullness", after PPG is alleviated by cisapride. Moreover cisapride therapy alleviates various abdominal symptoms, contributing to the improved postoperative gastrointestinal condition of patients after gastrectomy for early gastric cancer
(Tomita).
Asao mentions a laparoscopically assisted gastrectomy technique
with lymphadenectomy with recontruction by Billroth I or intestinal interposition for superficially invading gastric cancer.
He underlines the difficulty of obtaining an accurate diagnosis of the depth of invasion and nodal metastasis. Therefore he recommends an additional lymph node dissection which includes at minimum dissection of the common hepatic and celiac arteries ( Asao).
Nowadays limited surgery in EGC is recommended because the rate of lymph node metastasis is 2.4% for tumors limited to the mucosa, and preservation of regional lymph nodes may enhance postoperative immunocompetence.
But extended lymphadenectomy appears to prolong the survival of patients whose tumors invades the submucosa, in fact 11% of tumors invading the submucosa have lymphatic involvement but no lymph node metastasis. And a significant correlation exists between lymphatic involvement and lymph node metastasis.
Moreover in patients with submucosal gastric carcinoma the presence of micrometastasis in the extraperigastric lymph nodes may be missed, and in the same lymph nodes skip metastasis occur in 7% of EGCs .
The same author in another report affirms that performance of extended radical lymphadenectomy is a significant prognostic factor for EGC patients when tumors are located in the distal third of the stomach (Otsuji).
European surgeons generally justify limited resection strategies for EGC treatment only in high risk patients. The standard resection with systematic lymphadenectomy (D2) is supported by the presence of lymph node metastases in 10-20% of patients. Furthermore an EGC still must be diagnosed histologically, and skip metastases are described
(Jentschura ).
Postoperative appropriate adjuvant immunochemotherapy should be applied in the cases of positive lymph node metastasis (Kim).
References
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