Tadashi Koga

Gastrointestinal stromal tumors (GISTs) are the most common malignant subepithelial lesions (SELs) of the gastrointestinal tract. They originate from the interstitial cells of Cajal located within the muscle layer and are characterized by over-expression of the tyrosine kinase receptor KIT. Pathologically, diagnosis of a GIST relies on morphology and immunohistochemistry [KIT and/or discovered on gastrointestinal stromal tumor 1 (DOG1) is generally positive]. The prognosis of this disease is associated with the tumor size and mitotic index. The standard treatment of a GIST without metastasis is surgical resection. A GIST with metastasis is usually only treated by tyrosine kinase inhibitors without radical cure; thus, early diagnosis is the only way to improve its prognosis. However, a GIST is usually detected as a SEL during endoscopy, and many benign and malignant conditions may manifest as SELs. Conventional endoscopic biopsy is difficult for tumors without ulceration. Most SELs have therefore been managed without a histological diagnosis. However, a favorable prognosis of a GIST is associated with early histological diagnosis and R0 resection. Endoscopic ultrasonography (EUS) and EUS-guided fine needle aspiration (EUS-FNA) are critical for an accurate diagnosis of SELs. EUS-FNA is safe and effective in enabling an early histological diagnosis and adequate treatment. This review outlines the current evidence for the diagnosis and management of GISTs, with an emphasis on early management of small SELs.

BACKGROUND: Recurrence occurs in a variety of forms and in different organs after 'curative resection' of gastric cancer. This study investigated the postoperative prognosis for each type of recurrence. METHODS: From 1969 to 1988, 939 patients with gastric cancer underwent curative resection; data on 130 of 207 patients who died with recurrence were analysed. Attention was focused on the site of recurrence and the postoperative outcome. RESULTS: Haematogenous recurrence was evident in 54 per cent (70 of 130 patients), peritoneal recurrence in 43 per cent (56 of 130), lymph node recurrence in 12 per cent (16 of 130) and local recurrence in 22 per cent (29 of 130). Thirty-three patients (25 per cent) had recurrences at multiple sites. Peritoneal and local recurrences were related to infiltrative growth, in contrast to haematogenous and lymphatic recurrences. There were no statistical differences in survival time among each type of recurrence and survival was not related to the number of sites of recurrence. Survival did not depend on factors of sex, age, tumour location, tumour size, depth of invasion, tissue differentiation, histological growth pattern, lymphatic and vascular involvement, lymph node metastasis and extent of lymph node dissection. CONCLUSION: The clinicopathological characteristics of gastric cancer determine the type of recurrence, although the clinical outcome is the same for each type of tumour and is not related to the number of sites of recurrence.

BACKGROUND AND AIMS: There is no evidence of postoperative metastasis of gastric gastrointestinal stromal tumors (GISTs) smaller than 2 cm. The aim of this study was to evaluate the clinical usefulness of endoscopic ultrasound guided fine needle aspiration (EUS-FNA) for gastric subepithelial lesions (SELs) smaller than 2 cm. PATIENTS AND METHODS: Using a prospectively maintained EUS-FNA database, 90 consecutive EUS-FNAs of gastric hypoechoic solid SELs smaller than 2 cm diagnosed by EUS were evaluated retrospectively. The reference standards for the final diagnosis were surgery (n=44) and/or clinical follow-up (n=46) using esophagogastroduodenoscopy (EGD), CT, and/or ultrasonography (US). Additionally, immunophenotyping of specimens obtained by EUS-FNA and surgical resection specimens were compared. RESULTS: The diagnostic rate of EUS-FNA for gastric hypoechoic solid SELs smaller than 2 cm was 73% (66/90). Histological diagnosis of EUS-FNA showed 47 (52%) malignant SELs (44 GISTs, 1 glomus tumor, 1 SEL like cancer, and 1 malignant lymphoma), 19 (21%) benign SELs (14 leiomyomas, 4 ectopic pancreas, and 1 neurinoma), and 24 (27%) indeterminate SELs. In 44 surgically resected cases, the diagnostic accuracy of EUS-FNA using immunohistochemical analysis was 98% (43/44). There were no complications. Appropriate management was performed in 65 out of 66 SELs (98%) diagnosed by definitive EUS-FNA. After surgery, there was no recurrence of malignant SELs. CONCLUSIONS: EUS-FNA is an accurate and safe method in the pre-therapeutic diagnosis of gastric SELs smaller than 2 cm. EUS-FNA for gastric SELs smaller than 2 cm is a promising way to permit early management of patients with gastric SELs including GIST.