分化型胃癌の悪性度―形質発現の点から

Differentiated Adenocarcinoma of the Gastric and Intestinal Phenotype―Histological Appearance and Biological Behavior

要旨　分化型SM胃癌を対象に形質発現からみた悪性度の違いを組織型・脈管侵襲・リンパ節転移の点から検討した．その結果，乳頭腺癌(50％)では管状腺癌(25.4％)よりも胃型優位の形質をもつものが有意に多かった．また，全体でみると乳頭腺癌(44％)は管状腺癌(6％)よりもリンパ節転移率が明らかに高かった．乳頭腺癌の中では胃型優位のものが脈管侵襲率が明らかに高いが，胃型優位のものと腸型優位のものとの間でリンパ節転移率に有意差はなかった．また，リンパ節転移を欠く腸型乳頭腺癌が術後多発肝転移を来して死亡した症例が1例存在した．一方，管状腺癌では形質発現による脈管侵襲・リンパ節転移率に有意差はなかった．胃型(優位)乳頭腺癌の中に高悪性度のものが含まれていることは疑う余地もないが，形質発現からみた分化型胃癌の生物学的動態・悪性度の違いについては長期術後follow up例を含めた今後の検討を必要とする．

　To investigate its relationship with histology and clinicopathologic factors, differentiated gastric carcinomas with submucosal invasion were classified into simplified gastric phenotype (sG-type), simplified intestinal phenotype (sI-type) and Null phenotype (N-type).

　As a result, in papillary adenocarcinoma, the number of sG-type cases was significantly higher than that of sI-type cases. The incidence of lymph node metastasis in papillary adenocarcinoma (44％) was apparently higher than that of tubular adenocarcinoma (6％). In papillary adenocarcinoma, the incidence of lymphatic and venous invasion of sG-type carcinoma was higher than that of sI-type carcinoma. However, the difference in the incidence of lymph node metastasis between them was not significant. We encountered a case of papillary adenocarcinoma of intestinal phenotype with submucosal invasion, which lacked lymph node metastasis. About 1 year after the operation, the patient died of multiple liver metastasis. In tubular adenocarcinoma, there was no significant difference in the lymph node metastatic rate and the lymphatic and venous invasion rate between each phenotype. Needless to say, sG-type papillary adenocarcinoma cases included a relatively high degree of malignant cases. However, to investigate the difference of biological behavior and malignancy in differentiated adenocarcinoma from the viewpoint of its phenotype, future examination including postoperative long-term follow-up of cases is required.