Is型大腸sm癌のリンパ節転移危険因子に関する病理形態学的検索

Pathomorphologic Study Concerning Risk Factor of Lymph Node Metastasis in Colorectal Submucosal Invasive (sm) Carcinomas of Is Type

要旨　外科切除Is型大腸sm癌78例79病変について，リンパ節転移危険因子

を中心に病理形態学的立場から検討した．転移率は全癌10.1％，sm1癌5.9％，sm2癌10％，sm3癌119％と深達度別のそれに有意差はなかった．高分化腺癌8.5％よりも中分化腺癌28.6％で高い傾向がみられ，加えて転移陽性癌全8病変の発育先進部に低分化癌部を認めた．リンパ管侵襲程度に比例してly0.0％，ly118.8％，ly2.50％と増加し，lyoと後2者問には有意差が確認された．簇出群19.4％と非簇出群2.4％では前者に有意に高率であった．細胞増殖能Ki-67L.I.および癌抑制遺伝子産物p53，血管内皮増殖因子VEGF，増殖因子受容体蛋白c-erbB-2の発現は転移癌と非転移癌間に差はなかった．以上の結果から，リンパ管侵襲，簇出，組織型特に発育先進部の低分化像の3つが重要な危険因子であることを指摘し，局所切除の絶対的適応となるIs型癌はly0の癌と結論した．

　We studied 79 surgically resected colorectal sm carcinomas of Is type pathomorphologically with special reference to risk factors of regional lymph node metastasis. The incidence of lymph node metastasis was 10.1% (eight cases) among all of the 79 cases of colorectal sm carcinoma, 5.9% (one case) among 17 cases of sm₁ carcinoma, 10% (two cases) among 20 cases of sm₂ carcinoma, and 11.9% (five cases) among 42 cases of sm₃ carcinoma. However, no positive statistical correlation existed between the incidence and the depth of carcinomatous invasion in the submucosa. The incidence was higher in moderately differentiated adenocarcinomas (28.6%) than in well differentiated adenocarcinomas (8.5%). The difference between the moderately differentiated adenocarcinoma group and the well differentiated adenocarcinoma group was not statistically significant. All eight carcinomas with lymph node metastasis had foci of poor differentiation at least in a small portion of the advancing margins of the submucosa. The incidence of lymph node involvement increased according to the grade of lymphatic permeation, namely it was 0% in carcinomas without lymphatic permeation (ly₀), 18.8% in carcinomas with grade 1 lymphatic permeation (ly₁) and 50% in carcinomas with grade 2 lymphatic permeation (ly₂). A statistically significant difference existed between the incidence in carcinomas with ly0 and that in carcinomas with ly₁ or 1y₂. The incidence of lymph node metastasis was higher in carcinomas with sprouting of cancer tissue at advancing margins in the submucosa (19.4%) than in carcinoma without it (2.4%). The difference between the sprouting group and the non-sprouting group was statistically significant. There was no positive statistical correlation between the incidence of lymph node metastasis and tumor size, nor between the anatomical sites of the carcinomas. Moreover, no statistically significant difference existed between the mean labeling index of Ki67, the incidence of overexpression of p53 protein and the incidence of expression of VEGF and c-erbB-2 protein, between the metastatic group and the nonmetastatic group. According to the results, we were able to point out that lymphatic permeation, sprouting of cancer tissue, and histologic type, especially a poorly differentiated component at the advancing margins of the submucosa are the three important risk factors of lymph node metastasis in colorectal sm carcinomas of Is type. It was also shown that endoscopic resection for sm carcinomas of Is type is curative in carcinomas without lymphatic permeation.