大腸の腺腫と早期癌の形態推移

Developmental Process of Colorectal Adenoma and Early Carcinoma

要旨　大腸早期癌から進行癌へ発育増殖する過程で，肉眼形態がどのように変化するかを老察するため，腺腫417，早期癌220（m癌107，sm癌113），pm癌61の各病変につき肉眼形態と大きさ，腺腫混在率，腺腫成分の割合，腫瘍発生部位ならびにsm浸潤度分類，pm浸潤度分類から検討を行った．早期癌の形態推移には2つの大きな流れがあり，Ip，Ipsの形態で癌化し，15mm前後でsm癌へ移行し，sm_1c以上の浸潤レベルでIs方向へ向かう流れ（mountain route）と，Ⅱaあるいは微小Isの形態で癌化し，早期に10mm前後でsm癌へ移行し，15mm前後のsm_2～3の浸潤レベルでⅡa＋Ⅱcへ向かう流れ（direct route）の両者が存在することが示された．また腫瘍の発生部位により両者の頻度が大きく異なることが示された．

　Four hundred and seventeen colorectal adenomas and 220 early colorectal carcinomas, 107 intramucosal (m) and 113 submucosal (sm), were analyzed.

　On the basis of the result of our present analysis on changes of gross configuration of adenomas involved by malignant transformation, it is suggested that adenomas increase their size with changes of gross configuration from sessile type to subpedunculated and further to pedunculated type.

　It is also suggested that, depending on which stage of configuration the adenomas are involved by malignant transformation, the developing direction of gross configuration of these lesions is to be influenced. No significant influence to the gross configuration is considered when the lesion remains in the early stages of carcinoma with mucosal involvement down to sm_1b carcinoma, while the lesion may result in apparent changes of gross configuration when its invasion develops down to sm_1c or further beyond.

　It is proved that Ip (pedunculated) type of carcinoma with submucosal involvement transforms to Ips (subpedunculated) type until the stage of sm_1c and Ips type to Is (sessile) type until the stage of sm₂. Ⅱa＋Ⅱc (flat-elevated with depression) type of invasive carcinoma may transform Ⅱa (flat-elevated) type at the stage of sm_2～3. It is considered that the developing direction of gross configuration may be different when malignant transformation occurs in the form of Ips or Ip (mountain route) as compared with the form of Ⅱa or Is (direct route).