大腸sm癌のリンパ節転移危険因子の検討

Histopathologic Risk Factors for Lymph Node Metastasis of Submucosal Invasive Colorectal Carcinoma

要旨　大腸sm癌浸潤距離測定においては，粘膜筋板の走行が錯綜していて測定の基準線の同定が困難である例や，粘膜筋板が消失している例があるため，測定方法の標準化に難航している．本稿では，大腸sm癌329症例のsm浸潤距離の測定を5通りで行い，測定方法を検討したうえで，現在の規約で規定されているsm1,000μmの妥当性を検証した．また，浸潤距離以外のリンパ節転移危険因子を検討したところ，主組織型，リンパ管侵襲，簇出が有意な因子であった．その他に発育形式（PG/NPG），粘膜筋板の状態（A1・A2/B1・B2）がリンパ節転移危険因子となりうることが示唆された．

　In grading submucosal invasive colorectal carcinomas based on the depth of submucosal invasion, problems can be encountered in identifying the muscularis mucosae when it is complicated, has been obscured or has even disappeared completely because of the infiltration of cancer cells.

　We measured the depth of submucosal invasion in 329 cases of submucosal invasive colorectal carcinomas using 5 methods and then evaluated each of the methods.

　The lesions with over 1,000μm submucosal invasion have more frequent lymph node metastases than less invasive lesions, when we measured the depth of submucosal invasion from either the lower edge of the muscularis mucosae or the surface of the tumor using the criteria of the general rules for clinical and pathological studies on cancer of the colon, rectum and anus.

　The risk factors for lymph node metastasis were histological grade (moderately to poorly differentiation), lymphatic invasion and tumor budding. In addition, intramucosal growth type (PG/NPG) and status of the muscularis mucosae (A1・A2/B1・B2) also were risk factors.