大腸早期癌の臨床と病理

Clinical and Pathological Considerations on Early Cancer of the Large Bowel

　近来早期癌問題の関心がたかまり，大腸癌においても早期癌の実態を明らかにし，その基準を定めるように要求されている．以下主として臨床家の立場からこの問題を考えてみたい．

　Small cancer of the colon under 2cm in its largest diameter has been found in 3 per cent of all the resected cases of cancer of the colon. Having 100 per cent radical operability and all involving only less than one third of the circumference of the colon, this type of cancer was mostly localized within the mucosa or submucosa, and in nearly all cases no lymph node metastasis was demonstrated. Studies of such small cancers, or early cancers as they may be justifiably called, have progressed to such a degree that they can now be exploited in the histological study of carcinogenesis.

　Analysis of 65 lesions of early cancer of the large bowel diagnosed as such out of all operated cases reveals that pedunclated polypoid lesions are seen in 55.4%, sessile polypoid in 16.5, flat, irregular protrusion in 6.2 and ulcerated type in 21.5. Of 26 cases of single early cancer, pedunclated polypoid type is seen in 50%, sessile polypoid in 19.2, and ulcerated type in 30.8, as compared with Spratt's 20 cases of small cancer, where pedunclated type was seen in 6 (30%), sessile polypoid in 2 (10) and ulcerated type in 6 (30).

　Incidence of types in the authors’ cases might not be what it should have been because the motive for their detection was in a way restricted, but they are considered to embody all possible types. All the past disputes over their origination are seemingly due to the difference in the way of interpreting these facts. Accumulation of such cases and further investigations are eagerly expected.