The definition of early gastric cancer is that of a cancer in which tumor invasion is confined to the mucosa or submucosa regardless of the presence of lymph node metastasis (Gotoda).
Wang suggests another classification based on excellent prognosis rather than the depth of invasion: only node negative pT1 gastric cancer should be called early gastric cancer. The prognosis of node-positive pT1 and of node-negative pT2 gastric cancers would be not favourable enough to be categorized as EGC
(Wang).
The diagnosis of EGC has been increasing recently in several countries, including Korea and Japan, mainly because of the screening by gastrofiberscopy or upper gastrointestinal series. The incidence of EGCs among all gastric cancer increased in Korea from 14.9% (1974-1992) to 30% in 1994
(Kim).
In Western countries the percentage of EGC varies from 6% to 16%.
The high incidence and good prognosis of EGC in Japan might depend on the focusing more on nuclear factors and glandular structures by Japanese pathologists, and therefore adenoma and dysplasia being diagnosed as EGC
(Borie).
The most important prognostic factor for patients with EGC is the presence of lymph node metastasis (Gotoda).
In a retrospective study of 621 patients with EGC, Seto et al show that early gastric cancer patients with lymph node metastasis constitute a high risk recurrence group
(Seto).
Kim reports a 5 year survival rate of 94.5% for N0 (0 positive nodes), 88,3% for N1 (< 3 positive nodes), and 77,3% for N2 (>3 positive nodes)
(Kim).
But according to some authors's opinion there aren't standard histologic / pathologic measures as the "gold standard. When "negative lymph nodes" are sectioned serially, studied by immunohystochemical stains, or examined by molecular biologic techniques, they may be shown to harbor disease(Nakamura).
Borie affirms that both lymph node and lymphatic vessels involvement are important prognostic factors in patients with EGC.
Lymphadenectomy in EGC is important to identify the high risk population for whom prognosis is worse. The extent of lymphadenectomy (at least 15 nodes) in these patients, however, does not alter prognosis (see next articles in Surgical Oncology net).
According to Borie's study EGCs with LV involvement have the same prognosis as EGCs with LN involvement and LV without LN involvement is a poor prognostic factor. This may be assimilated to the so called micrometastasis of Siewert et al
(Borie).
The standard treatment has been gastrectomy with D2 lymph node dissection. In consequence of postprandial symptoms and nutritional problems in patients with EGC after gastrectomy, surgeons have attempted minimally invasive surgical treatments (Ishigami).
However Kim recommends that lymph node dissection is necessary for EGC in addition to gastric resection, in patients with high risk of lymph node metastasis
(Kim).
For intramucosal cancer it has been generally accepted a local treatment (endoscopic mucosal resection), because lesions with a differentiated histological type and without lymphatic-vascular involvement or ulcerative findings within the cancerous lesion have a minimal risk of lymph node metastasis
(Gotoda).
In patients with submucosal invasive cancer the incidence of lymph node metastasis is approximately 20 per cent (Gotoda), and 2.6%- 3,4% for mucosal lesions
(Kim).
Gastrectomy with complete removal of first- and second-tier lymph nodes assures a 96% survival rate at 5 years.
Gotoda selects the patients with submucosal invasive cancer having a minimal risk of lymph node metastasis, to achieve a purpose of minimizing the negative effects of surgery on the quality of life.
Patients with differentiated tumours, smaller than 30 mm, without lymphatic-vascular involvement and with a submucosal penetration of less than 500 micronm have no lymph node metastasis (Gotoda).
Yasuda considers tumor size and depth of submucosal invasion as useful indicators of lymph node metastasis in early stage gastric carcinoma.
He suggests that the optimal lymph node dissection levels for gastric carcinoma invading the submucosa are: 1) local resection without lymph node dissection (D0), such as endoscopic mucosal resection and laparoscopic wedge resection, for lesions less than 1 cm; 2) limited lymph node dissection (D1) under laparotomy or laparoscopic assisted surgery for 1 to 4 cm lesions; and 3) radical lymph node dissection (D2) for lesions larger than 4 cm .
If submucosal invasion of the locally resected tumour is more than 300 micronm additional gastrectomy with lymph node dissection (D1, D2) should be performed
(Yasuda).
It is recommended by Ishigami to add a two dimensional examination of submucosal invasion to more accurately identify patients who have gastric cancer but are free of nodal involvement. The author distinguishes between different depth of invasion and considers the horizontal length of carcinoma invasion into the submucosa, measured as the maximum width in hematoxylin and eosin-stained sections. He finds that all patients with sm1 invasion and less than 5 mm of submucosal invasion are free of nodal involvement
(Ishigami).
Kim confirms the importance of the two dimensional examination of submucosal invasion : tumor size may not reflect the diameter of the submucosal infiltration.
Moreover the rate of lymph node metastasis is high for lesions that are > 30mm, poorly differentiated, or microscopically diffuse, as well as for antral lesions, submucosal lesions (types I and IIa), depressed/mixed type lesions, and lesions with ulceration.
Lymphatic spread seems to predict nodal involvement
(Kim).
Tsujitani in a retrospective study of 890 patients with EGC who had undergone standard gastrectomy examines the possibility of a limited lymph node dissection and limited gastrectomies (EMR, wedge resection, segmental gastrectomy, limited proximal gastrectomy, and distal hemigastrectomy).
Multivariate analysis shows that the indipendent risk factors for lymph node metastasis in patients with EGC are large tumor size, involvement of lymphatic vessels and invasion of the submucosal layer.
The poorly differentiated type is associated with nodal involvement.
The author concludes that tumor size and gross appearance are the most reliable factors in choosing a therapeutic procedure
(Tsujitani).
To assess these criteria is necessary a complete histological examination of the endoscopically resected specimen (including the submucosal layer), to decide whether an additional surgical procedure is warranted (Gotoda).
When the size of the tumour exceeds 15 mm the assessment of the depth of submucosal invasion in an endoscopically resected specimen is difficult, because such lesions are often resected in multiple fragments ( Korenaga).
Another technique of endoscopic resection using an insulation-tipped electrosurgical knife to remove a large lesion en bloc has been developed. The lesions larger than 15 mm if resected en bloc, are examined as accurately as surgically resected material (Gotoda ).
It is not possible an absolute certain pre-treatment endoscopic diagnosis, in fact it is correct in only 80 per cent of tumors (Ohashi ).
To define the depth of invasion and the presence of lymph node metastases abdominal ultrasonography, abdominal computed tomography(CT) and endoscopic ultrasonographic analysis of the gastric wall are now used
(Kim).
References
Kim J-P. Invited Commentary. Worl J Surg. 22, 1059, 1998.
Gotoda T et al. Evaluation of the necessity for gastrectomy with lymph node dissection for patients with submucosal invasive gastric cancer. British Journal of Surgery 2001, 88, 444 - 449.
Korenaga D et al. Pathological appearance of the stomach after endoscopic mucosal resection for early gastric cancer. British J Surgery 1997, 84: 1563-6.
Gotoda T et al. A new endoscopic mucosal resection (EMR) procedure using an insulation-tipped electrosurgical knife for rectal flat lesions: report of two cases. Gastrointest Endoscop 1999; 50: 560-3.
Ohashi S et al. The utility of endoscopic ultrasonography and endoscopy in the endoscopic mucosal resection of early gastric cancer. Gut 1999; 45: 599-604.
Yasuda K et al. Rate of detection of lymph node metastasis is correlated with the depth of submucosal invasion in early stage gastric carcinoma.
Cancer 1999; 85 : 2119-23.
Sumiya Ishigami et al. Carcinomatous infiltration into the submucosa as predictor of lymph node involvement in early gastric cancer.Worl J Surg. 22, 1056-1060, 1998.
Seto Y et al. Impacat of lymph node metastasis on survival with early gastric cancer. World J Surg. 21:186,1997.
Frederic Borie et al. Lymphatic involvement in early gastric cancer. Arch Surg 2000; 135: 1218-1223.
Chia-Siu Wang et al. Prognostic Study of Gastric Cancer without serosal invasion: reevaluation of the definition of Early Gastric Cancer. J Am Coll Surg 1997; 185:476-480.
Shunichi Tsujitani et al. Less invasive surgery for early gastric cancer based on the low probability of lymph node metastasis. Surgery 1999; 125:148
Kenjiro Nakamura et al. An Early Gastric Carcinoma treatment strategy based on analysis of lymph node metastasis. Cancer 1999; 85:1500-5.
Takeshi Sano et al. The management of early gastric cancer. Surgical Oncology, 2000; 9, 17-22.
Japanese Gastric Cancer Association. Japanese classification of gastric carcinoma- 2nd English edition. Gastric Cancer 1998; 1:10-24.
Kurihara N et al. Lymph node metastasis of early gastric cancer with submucosal invasion. British J Surgery 1998, 85, 835-39.
