胃sm癌の細分類からみた縮小手術の可能性―多変量解析を用いたリンパ節転移の予測と腹腔鏡下切除の可能性

Possibility of Reduction in Lymph Node Dissection in Gastric Submucosal Cancer: In View of Prediction of Lymph Node Metastasis by Logistic Regression Analysis, and Indication for Laparoscopic Resection

要旨　腹腔鏡下胃局所切除は1996年から保険適用が認められ，m癌に対しては散発的に開始されている．本術式をsm癌にまで適応拡大してよいか否かについて，sm癌深達度細分類に基づくリンパ節転移の多変量解析の検討から考察した．リンパ節転移の危険予測因子はリンパ管侵襲，腫瘍径，潰瘍合併，静脈侵襲であり，sm深達度細分類はリンパ管侵襲に代わりうる重要な予測因子であった．過去のリンパ節転移陽性例の検討と合わせると，D₁以下の郭清が許容されるのは高分化型のsm₁癌であったが，sm深達度，脈管侵襲の術前診断の不確実性を考慮すると，現時点で腹腔鏡下手術を術前sm浸潤が疑われる病変に適応拡大することは危険であり早計であると考えられる．

　Since 1996, laparoscopic resection has been approved in Japan as a method for curative treatment of gastric mucosal cancer, but it is still controversial whether laparoscopic resection without lymph node dissection or with limited lymph node dissection is indicated for gastric submucosal cancer, because the frequency of lymph node metastasis in submucosal cancer is nearly 20％. The objective of this study was to establish the indication for laparoscopic resection of submucosal carcinoma from the standpoint of lymph node metastasis using logistic regression analysis and to assess the classification of submucosal cancer into sm₁ ～ sm₃. The covariants which could predict lymph node metastasis were lymph vessel invasion, size of tumor, presence of ulceration and venous invasion. When we could not determine precisely the presence of vessel invasion prior to resection, classification of submucosal cancer into sm₁ ～ sm₃ became important. From our study laparoscopic resection with limited lymph node dissection (D₁) is indicated for well differentiated sm₁ cancer. However, we cannot diagnose precisely the degree of submucosal invasion or vessel invasion prior to resection, and we think it is dangerous to resect laparoscopically gastric cancer that has been diagnosed with submucosal invasion prior to surgery.