大腸癌の深達度診断―X線・内視鏡併用の立場から

Diagnosis of the Depth of Invasion of Colonic Cancer, from Radiologic and Endoscopic Viewpoints

要旨　40mm以下の大腸癌382病変と平坦・陥凹型大腸腺腫49病変を対象とし，癌は大きさの増大と共に深達度を増すとの仮定のもとに検討した．腺腫成分の有無を考慮し，肉眼形態別〔Pp型：有茎性隆起，Ps型：無茎性隆起，PD型：周辺隆起を有する陥凹型と中心陥凹を有する隆起型，FD型：周辺隆起を有しない平坦・陥凹型〕にみると大きさと深達度は強い関係を示した．ただし，PD型は大きさの増大と共に急激な浸潤を示すが，同様の形態を呈する微小病変はほぼ全例が腺腫の診断であり，m癌から進行癌への進展がうまく説明できなかった．いずれにしても，肉眼形態別に分け，腺腫成分の有無を考慮すれば，大きさは深達度診断の大きな指標になりうる．更に，Ps型では表面性状，PD型では空気量の変化に伴う周辺隆起の形態変化を加味すれば深達度診断の正診率はより高まると思われた．

　To evaluate the hypothesis that vertical cancer invasion may progress with the size of tumor, correlation between the depth of invasion and the size of tumor was analyzed on 382 colonic cancers less than 40 mm in size and 49 colonic adenomas by radiologic, endoscopic and pathologic examinations. Statistical analysis was done by regression analysis. Macroscopic features were classified into the following four types depending on the existence of adenomatous components: Pp type; pedunculated elevation, Ps type; sessile elevation, PD type; depressed lesion with surrounding elevation or elevated lesion with a central depression, FD type; flat or depressed lesion without surrounding elevation. Within each group, the size and the depth of invasion were strongly correlated. PD type lesions had tendency to infiltrate rapidly with their enlargement, however almost all the similar shaped minute lesions were diagnosed as adenomas. Therefore, the developmental process from m cancer to advanced cancer in this type could not be elucidated. Within each group of the macroscopic classification which were classified by the existence of adenomatous components, the size of the lesions was an important index to evaluate the depth of invasion. The nature of mucosal surface of Ps type lesions and change in the surrounding elevation of PD type lesions by pneumatic expansion may contribute the diagnostic accuracy of the depth of invasion.