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|EGC: the depth of invasion. |
Romeo Giuli MD, resident.
School of General and Emergency Surgery.
University of Siena. Italy.
September 2002. Review Article.
For nontraditional resections, the depth of invasion must be clearly limited to the mucosa. Preoperative EUS has made much progress over the last few decades and has proved to be valuable tool in preoperative staging.
EUS divides the gastric wall into five layers, the hyperechoic first layer, (mucosa), the hypoechoic second layer (deep mucosa or muscolaris mucosa ), the hyperechoic third layer ( submucosa ), the hypoechoic fourth layer ( muscolaris propria ), and the hyperechoic fifth layer ( serosa ).
T1 lesions have been accurately differentiated from T2 lesions ( accuracy of 100% by Tseng et al and 85,7% by Mancino et al ), however, the accuracy of diagnosing the depth of invasion ( whether mucosa or submucosa ) is still difficult, especially when there is coexisting ulceration. Even in the best hands, the accuracy has been approximately 73% to 100% for mucosal cancer and 73% to 85% for submucosal cancer without ulceration
3 ) .
Ultrasonography findings indicative of submucosal invasion include irregular narrowing of the hyperechoic third layer and budding signs. More than 90% of cancers that have been endoscopically diagnosed as mucosal but histologically proved to be submucosal ( differentiated adenocarcinoma without ulceration ) have had at least one of these features
( 4 ).
According to Nakamura study the accuracy of diagnosing cancer without ulceration that invades the submucosa was 58% with radiographs, 55% with endoscopy, and 85% with EUS
( 5 ).
In the Kunisaki study conventional endoscopy or barium meal studies were more useful than EUS in diagnosing the depth of invasion in early gastric cancer
( 6 ).
Given the current diagnostic ability, histologic evaluation of resected specimens seems to be the only accurate method of diagnosing the depth of tumor invasion
( 1 ).
1) Y Noguchi et al. Is there a role for nontraditional resection of early gastric cancer? Surg Oncol Clin N Am 11 ( 2002 ) 387-403.
2) Tseng LJ et al. Video-endoscopic ultrasonography in staging gastric carcinoma. Hepatogastroenterology 2000; 47: 897-900. Pub Med
3) Mancino G et al. Preoperative endoscopic ultrasonography in patients with gastric cancer. Tumori 2000; 86: 139-41. Pub Med
4) Matsumoto Y et al. Endoscopic ultrasonography for diagnosis of submucosal invasion in early gastric cancer. J Gastroenterology 2000; 35: 402-3. Pub Med
5) Nakamura T et al. Assessment of depth of invasion of gastric carcinoma by endoscopic ultrasonography ( EUS ) focussed on peptic ulceration within cancerous area. Stomach Intestine 1999; 24: 1105-17.
6) Chikara Kunisaki et al. Appropriate lymph node dissection for early gastric cancer based on lymph node metastases. Surgery 2001;129:153-7. Pub Med
7) Willis S et al. Endoscopic ultrasonography in the preoperative staging of gastric
cancer. Surg Endosc 2000; 14: 951-4. Pub Med
8) Akahoshi K et al. Pretreatment staging of endoscopically early gastric cancer with
a 15 MHz ultrasound miniprobe. Br J Radiol 1997; 70: 703-7.
9) Akahoshi K, Chijiwa Y, Hamada S, Sasaki I, Nawata H, Kabemura T, Yasuda D, Okabe H. Pretreatment staging of endoscopically early gastric cancer with a 15 MHz ultrasound catheter probe. Gastrointest Endosc 1998 Nov;48(5):470-6. Pub Med
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