X線学的逆追跡からみた大腸癌の発育経過―PG癌とNPG癌の初発病変の形態

Growth and Progression of Colorectal Cancer from Retrospective Radiographic and Histologic Analysis

要旨　進行癌の大多数を占める2型癌が表面陥凹型起源か否かを検討するため，逆追跡例を用いて進行癌の初期像の分析を試みた．対象は初回X線像が早期癌と推定された45病変．その初回X線像は，表面陥凹型（Ⅱc）11病変，表面隆起型（Ⅱa）11病変，隆起型（EL，Ⅰp，Ⅰsp，Ⅰs）23病変であった．最終時の切除標本の病理像から早期癌15病変，mp癌10病変（PG7病変vsNPG3病変）とss以深癌20病変（PG10病変vsNPG10病変）に分け，それぞれの初回X線像と発育形式とを対比した．その結果，早期癌では病理学的なNPG癌の初回X線像はⅡcで，PG癌のそれはⅡaとELであった．またPG進行癌の初回X線像はEL・Ⅱaであった．しかし，病理学的にmp-NPG癌と診断された病変はELとⅡcから発育・進展し，ss以深-NPG癌はEL・Ⅱaから発育・進展したものが多かった．病理学的なPGとNPGの判定は早期癌に限定されるべきである．進行癌では初回PGと推定される病変が，NPGへと無視できない頻度で変化した．逆追跡例からみると，2型進行癌は隆起型・表面隆起型病変から発育・進展するものが多いと考えられる．

　The present study was undertaken to elucidate the relationship between ulcerating-circumscribed advanced cancers and their precursor lesions, using retrospective radiographic analysis. The subjects were 45 lesions where the initial lesions were diagnosed as early cancer or adenoma. The initial lesions were divided according to radiographic pictures into 11 superficial depressed (Ⅱc) lesions, 11 superficial elevated (Ⅱa) and 23 elevated lesions (Ⅰp, Ⅰsp, Ⅰs) . Histologically, the final lesions were classified into m・sm-PG (eight cases), m・sm-NPG (seven cases), mp-PG (seven cases), mp-NPG (three cases), ss-PG (10 cases), ss-NPG (10 cases). Results of analysis of the initial lesions showed that in early cancer NPG ca. developed from Ⅱc only. PG ca. developed from Ⅱa and EL. However, most of mp-NPG ca. and ss-NPG ca. developed from EL or Ⅱa lesions.

　Conclusion : Classification of PG and NPG should be indicated in early cancer because in advanced cancer, lesions with PG frequently changed into lesions with NPG. From these results, it is concluded that viewed from retrospective radiographic study, most advanced cancers derived from elevated or superficially elevated lesions.