表面型大腸癌の発育経過―X線学的遡及例の検討

Natural History of the Superficial Type of Colon Cancer: Retrospective Radiological and Histological Analysis

要旨　表面型起源の大腸癌17病変と無茎性隆起型早期癌起源の大腸癌12病変の発育経過をX線所見を中心に遡及的に分析した．表面陥凹型癌の初回病変径は平均11.7mmで，腫瘍倍加時間は32.3か月であった．表面隆起型癌の初回病変径は11.5mmで倍加時間は22.3か月であった．両者ともに腺腫の併存は少なく，進行癌への移行は低率で発育速度は無茎性隆起型のそれに比し緩やかであった．形態変化については，表面隆起型の癌の多くは無茎性隆起の形態へ移行し，表面陥凹型の癌は形態変化が少なかった．また表面型癌のうち発育が緩やかなものは低異型度癌であった．これに対し，無茎性隆起型癌の初回病変径は平均15.7mmと大きく，既にsm癌とみられる病変が多く，進行癌への移行は高率であった．以上から表面型癌はsm癌にとどまる間は比較的緩やかに発育し，肉眼型の形態変化は深達度の進行と共に一定の経過をたどることがわかった．

　Seventeen colon cancers derived from the superficial type of colon cancer and twelve colon cancers derived from the early sessile type of colon were analyzed retrospectively and radiographically. The initial lesions of the superficial depressed cancers were 11.7 mm in diameter and the time taken for them to double in size was caluculated to be 32.3 months. The initial lesions of the superficial elevated cancers, which were 11.5 mm in diameter took 22.3 months to double in size. Superficial cancer rarely had concomitant adenomatous components, and they did not develop rapidly into advanced cancers.

　In contrast, in their initial lesions, colon cancers derived from sessile-type cancers were larger than those derived from superficial-type cancers. In addition,75% of them were suspected to be submucosally invasive, and they developed more rapidly than the superficial type of cancers. The sessile type of cancers had concomitant adenomatous components in a few cases and developed into advanced cancers much more frequently. During the period of observation, the superficial depressed-type of cancers did not change very much from their original configuration, and their growth rates were rather slow. The cancers which, according to Watanabe's cytological criteria, had a low grade of cellular atypicality developed more slowly than cancers with a high grade of cellular atypicality.