原発性びまん浸潤型大腸癌40例の臨床病理学的検討

原発性びまん浸潤型大腸癌は稀な疾患である.今回我々は教室で手術的に切除された原発性びまん浸潤型大腸癌の40例(男:女=1:1.1)について検討した.平均年齢は58.3歳で,占居部位は直腸およびS状結腸で全体の57.5%を占めていたが,生存率は右側結腸群で有意(p=0.0364)に低かった.腸管閉塞に伴う症状が多く,肝転移陽性例(28.9%),腹膜播種性転移陽性例(48.6%)と高度進行例が多く根治切除が困難であった.組織型では高・中分化型で全体の62.5%を占めていたが,予後は低分化型・印環細胞癌・粘液腺癌群で有意(p=0.0475)に不良であった.壁深達度は全例ss(a1)以深であり,高度のリンパ管侵襲を認め,78.9%がリンパ節転移陽性であった.静脈侵襲は83.3%に認められた.平均生存期間は21.6ヵ月であり半数以上(27例)は術後1年半以内の早期に再発死亡していた.21.6ヵ月未満生存例をA群,21.6ヵ月以上生存例をB群とし2群間で比較検討したところA群で有意に右側結腸の症例が多く(p=0.0241),リンパ管浸潤の高度な症例が有意(p=0.0423)に多かった.また有意差はなかったが,A群では腹膜播種性転移が多く,B群では肝転移陽性例が多い傾向がみられた.術後の抗癌剤治療を行った場合と行わなかった場合では生存率に有意差(p=0.0222)があり,術後抗癌剤治療は生存率を改善する可能性があると考えられた.We analyzed 40 patients with resection for rare primary diffusely infiltrating colorectal carcinoma in our department. Although rectal and sigmoid colon lesions accounted for 57.5%, a patient group with right-sided colon carcinoma exhibited significantly poorer survival (p=0.0364). Many patients revealed advanced colorectal carcinomas: 28.9% and 48.6% of patients showed liver metastasis and peritoneal dissemination, respectively, making radical resection difficult. Well- and moderately-differentiated adenocarcinomas constituted 62.5% of all carcinomas, and poorly differentiated adenocarcinomas, signet-ring cell carcinomas, and mucinous adenocarcinomas had a significantly poorer survival rate (p=0.0475). All carcinoma invasion depths were ss (a1) or deeper, showing marked lymphatic invasion, with lymph node metastasis in 78.9% of patients. Venous invasion comprised 83.3%. Median survival was 21.6 months, and more than half died of recurrent carcinoma within 18 months postsurgery. Patients who survived for less or longer than 21.6 months were classified as groups A and B, respectively. Group A included significantly greater numbers of patients with right-sided colon carcinoma (p=0.0241) and severe lymphatic invasion by carcinoma (p=0.0423). Groups A and B more frequently exhibited peritoneal dissemination and liver metastasis, respectively. Patients receiving postoperative chemotherapy with anticancer agents exhibited significantly longer survival than those who did not (p=0.0222), suggesting that postoperative anticancer chemotherapy improves survival