3）発育進展―経過観察例による臨床的解析

Natural History of Colorectal Cancer

要旨　九州地区30施設の大腸癌のX線学的遡及例110病変，内視鏡学的遡及例44病変を分析し，進行癌の初期形態と発育過程を検討した．進行癌の初期像として，X線学的遡及例ではIsが34.2％，IIaが19.2％を占め，内視鏡学的遡及例ではIsが38.5％，IIaが23.1％を占めた．さらに2型進行癌の初期像はX線，内視鏡学的遡及例ともにIsが最も多かった．2cm以下の小さな進行癌の初期像については，X線学的遡及例では隆起型（Isp，Is）が42.9％，表面型（IIa，IIa＋IIc，IIc・IIc＋IIa）が57.1％で内視鏡学的遡及例では隆起型（Isp，Is），表面型（IIa，IIc・IIc＋IIa）ともに50％だった．肉眼形態別の癌の発育速度は様々だったが，表面陥凹型10病変のdoubling timeを検討したところ，最終M癌の52.8か月に対しSM癌，MP以深癌では14.7か月，6.9か月だった．腺腫からM癌，SM癌，進行癌までの平均観察期間は78.5か月，41.8か月，64.5か月だった．進行癌へ進展した大腸腺腫の初期病変はIsが46.2％，IIaが23.1％，Ispが5.4％だった．以上より進行癌の初期像は隆起型が多く，表面陥凹型は深部浸潤に伴い極めて急速に増大する傾向にあった．また，10mm未満の大腸腺腫の癌化には約6年を要した．

　We analyzed 110 radiographic colorectal cancer lesions retrospectively as well as 44 endoscopic colorectal cancer lesions at 30 institutions in the Kyushu district. According to their appearance in the initial stage, 34.2% of the radiographic cases were Is and 19.2% were IIa, and among the endoscopic cases 38.5% were Is and 23.1% were IIa. In addition, Is was the most common appearance of Type 2 advanced cancers in the initial stage in both the radiographic and the endoscopic cases. The results for the appearance of small advanced cancers measuring 2cm or less in the initial stage showed that the protruded type accounted for 46.2% of the retrospective radiographic cases and the superficial type for 53.8%, and that among the retrospective endoscopic cases the protruded type and the superficial type each accounted for 50.0%. The doubling time of 10 superficial depressed type lesions was ultimately 14.7 months and 6.9 months for SM cancers and MP and deeper cancers, respectively, as opposed to 52.8 months for M cancers. The mean follow-up time from adenoma to M cancer, SM cancer, and advanced cancer was 78.5 months, 41.8 months, and 64.5 months, respectively. Based on the above findings, the most common early appearance of advanced cancer was the protruded type, and the superficial depressed type was associated with deep invasion and tended to grow more rapidly.