Prevalence of Sub-epithelial Lesions Among Patients Undergoing EGDs in Egypt

Worldwide, the gastrointestinal (GI) tract is the organ system with the highest cancer incidence (20.5% of all new cases) and annual mortality (22% = 1.81 Mio). Early endoscopic detection and resection has led to improved survival rates for colorectal and gastric cancer, especially for gastric cancer in Japan, where more than 70% are now detected as early gastric cancer. Subepithelial lesions (SELs) of the GI tract are tumors that originate from the muscularis mucosa, submucosa, or muscularis propria. The term subepithelial lesion is preferred to the term submucosal tumor, which should be reserved for those that originate from the submucosal layer. SELs are most commonly found in the stomach, as often as 1 in every 300 endoscopies. The majority of these tumors are benign, with fewer than 15% found to be malignant at presentation.

Subepithelial lesions (SEL) are incidentally observed in the stomach of about 0.3% of middle-aged men and women; half of these are neoplastic. The incidence of subepithelial tumors (SET) of gastrointestinal (GI) origin has risen twofold to fivefold within the past 30 years.

According to the Korea EUS Study Group (unpublished data), the prevalence of gastric SETs, detected routine esophagogastroduodenoscopy, in Korea is 3.1%.

The etiology of most SMTs cannot easily be determined by endoscopy. Subepithelial lesions are those located beneath the epithelium and originate from any layer of the gastrointestinal wall. EUS is the best imaging modality to assess gastrointestinal subepithelial lesions and can be used for EUS guided tissue sampling, in addition to diagnostic imaging of the nodule. It helps to distinguish extrinsic lesions from intramural ones based on the originating layer, echogenicity and tissue acquisition to reach an accurate diagnosis. In clinical practice, cytological and immunocytochemical results determine the final diagnosis. EUS is superior to other imaging modalities (CT, magnetic resonance imaging) in characterizing small (<2 cm) lesions.

NCCN guideline on GISTs recommends resection of all symptomatic lesions, any lesions that are ≥2 cm, or lesions that have high risk features under EUS. Annual surveillance is recommended for low risk GISTs. Neuroendocrine tumours (NET) , meanwhile, has higher malignant potentials. Some investigators advocate resecting all visible lesions. The minimal approach should be to resect tumors ≥1 cm in diameter. NET require surveillance similar if not more stringent than GIST.