特殊型胃癌の臨床的特徴―胃癌取扱い規約第14版をうけて

Significance of the Histological Special Type of the Gastric Carcinoma in the 14 th Edition of the JGCA Classification

要旨　1994～1998年に当院で切除された，SM以深の胃癌468例を特殊型胃癌（「胃癌取扱い規約第14版」）に焦点を当てて検討した．特殊型は43例（9.2％）であり，内分泌細胞癌8例，リンパ球浸潤癌21例，肝様腺癌14例であった．これらの第13版における組織型はpor1 32例，pap 4例，tub2 4例，tub1 1例，por2 1例，nec 1例であった．全例で予後が確認でき，内分泌細胞癌と肝様腺癌の5年生存率は25.0％，35.7％であり，SM以深胃癌全体の66.0％に比べ有意に低かった．リンパ球浸潤癌は95.2％で，有意に高かった．また，今回の検討期間には含まれていなかったが，過去に扁平上皮癌5例，腺扁平上皮癌4例を経験しており，これらを第14版での診断基準で再検討すると扁平上皮癌1例，腺扁平上皮癌4例であった．特殊型は頻度が低く，その診断は困難であるものの今回の改訂で大幅に増加し，今後その重要性が期待された．

　Four hundred and sixty-eight patients who had gastric cancer with invasion deeper than the submucosal layer and whose outcome was determined were examined, focusing on special type gastric carcinoma based on the 14th edition of the Japanese Classification of Gastric Carcinoma. Of the 468 patients, 43（9.1％）were classified as special type, consisting of 8 with endocrine cell carcinoma, 14 with hepatoid adenocarcinoma, and 21 with carcinoma with lymphoid stroma. According to the histological typing of the 13th edition, these patients included 32 patients with por 1, 4 patients with pap, 4 patients with tub 2, 1 patient with tub 1, 1 patient with por 2, and 1 patient with nec. The outcome of all the patients was determined, and 5-year survival rates were 25.0％ for endocrine cell carcinoma and 35.7％ for hepatoid adenocarcinoma. These rates were significantly lower compared with the survival rate of 66.0％ in all patients who had gastric cancer with invasion deeper than the submucosal layer. The 5-year survival rate was 95.2％ in patients who had carcinoma with lymphoid stroma, which was significantly high. Our previous 5 and 4 patients not included in this study had been classified as squamous cell carcinoma and adenosquamous carcinoma, respectively ; but, when they were reexamined according to the 14th edition, only 1 patient was classified as squamous cell carcinoma and 4 patients as adenosquamous carcinoma. Special type gastric carcinoma is difficult to diagnose because of its low frequency ; but, the present 14th edition of Japanese Classification of Gastric Carcinoma will increase the cases of special type gastric carcinoma, and its importance is expected to increase.