表層拡大型早期胃癌のX線および内視鏡的術前診断の検討

Preoperative Radiologic and Endoscopic Diagnosis of the Superficially Spread Type Early Gastric Cancer

要旨　表層拡大型（表拡型）早期胃癌の定義は，癌の平均径が8cm以上で深達度がsmまでにとどまるものとした．1981年～1993年の13年間に癌研外科で切除された全胃癌3,690例に対する表拡型早期胃癌の頻度は0.79％（29例）である．表拡型癌29例を対象に臨床病理学的診断の立場から検討した．癌の主占拠部位別頻度では胃体部領域が最も多く21例（72％）であった．肉眼型別頻度は陥凹型が多く76％（22例）であった。Ⅱb合併は3例（10％）であった．癌組織型は未分化型が多く69％（20例）であった．深達度では粘膜下層（sm）が多く66％（19例）であった．背景粘膜の腸上皮化生程度では高度な例が多く45％（13例）であった．リンパ節転移は11例（38％）にみられた．術前の拡がり診断率は，X線検査90％，内視鏡検査79％であった．分化型と未分化型の混合型が12例（41％）を占めていたこと，癌の拡がり方が同心円状でなく奇異な形の拡がりを示した癌が6例（21％）であったことから，表拡型早期胃癌の多くは多中心性に発生した癌が互いに融合して，1つの癌巣を形成していることが考えられた．

　The superficially spread type early gastric cancer (SSEGC) is defined as follows the average diameter of the tumor is more than 8 cm in size and the depth of invasion is limited within the submucosal layer (sm). For 13 years between 1981 and 1993, there were 29 cases (0.79%) of SSEGC in 3,690 cases of surgically treated gastric cancer in the Cancer Institute Hospital, Department of Surgery. These 29 cases of SSEGC were evaluated from the clinico-pathological viewpoints and results were summarized as follows. 1) Anatomical subsites: Most of the SSEGC (21 cases) were located in the middle third of the stomach. 2) Macroscopic type: Depressive type (22 cases, 76%) was most common, but 3 cases (10%) were accompanied by type Ⅱb. 3) Histologic type poorly differentiated type (20 cases, 69%) was most common. 4) Depth of invasion: Sixty six percent (19 cases) of the SSEGC were classified as sm. 5) Forty five percent (13 cases) of the SSEGC were associated with severe intestinal metaplasia in the background mucosa. 6) Eleven cases (38%) of the SSEGC had lymph node metastasis. 7) Accuracy rates of preoperative diagnosis on the extent of the disease by the radiologic and endoscopic examinations were 90% and 79% respectively. Twelve cases (41%) were found to be mixed with poorly and well differentiated carcinomas, and 6 cases (21%) had strange shaped spread of the tumor (not a concentric circle shape), therefore SSEGC may be formed by fusion of multicentered carcinomas.