陥凹型早期大腸癌の成因と内視鏡像に関する検討

A Study on the Genesis of Depressed-type Eearly Colon Cancer and Its Colonoscopic Findings

要旨　6例の陥凹型早期大腸癌について検討した．陥凹の定義は切除標本肉眼像を基本にし，それで陥凹部分が大部分を占めるものとした．成因としては，①水平急速発育，②未分化癌，③腫瘍の崩壊脱落，の3つが考えられた．内視鏡像では発見のきっかけとして，陥凹，平坦，扁平隆起であるを問わず限局性の発赤を重視すべきであることがわかった．陥凹型早期癌の好発部位として直腸と横行結腸があるが，特に後者は早期癌の少ない部位であり注目される．また陥凹型癌は進行癌に合併（同時，異時）してみられることが多く，癌の術後のフォローにおいて特に直腸・横行結腸で陥凹型癌に注意すべきである．

　Six cases of depressed-type early colon cancer were studied. The definition of depression is based on the macroscopic appearance of the resected specimen. Depressed early cancers were defined as those in which the depressed area occupied more than half of the lesion.

　Our study revealed that there exist three geneses of depressed cancers ; (1) lateral expansive growth, (2) undifferentiated carcinomas, (3) collapsed tumors.

　Redness was shown to be very important as a clue for discovery of the depressed lesions. The rectum and transverse colon were the predominant locations for depressed early cancer. Depressed ealy cancers were often accompanied by advanced cancer. Therefore, in the post-operative follow-up of advanced cancer, depressed early cancer must be carefully checked, particularly at the rectum and transverse colon.