大腸癌のスクリーニング

Screening for Colorectal Cancer

　胃癌の早期診断のためのX線・内視鏡検査技術と診断理論の大腸診断学への導入によって，大腸疾患の診断も確実になしうるようになってきている．しかし精密検査法としてのこれらの大腸検査法には，前処置を要すること，検査手技が複雑であること，生殖器へはX線被曝が避け難いこと，などの問題点があるため，胃検査法のように簡単には検査を行えない隘路がある．

　一方，日本人にとっても大腸癌が近い将来，欧米人と同様に重大な死亡原因になることが予想されており¹⁾，早急にその早期診断のためのスクリーニング検査法の確立が必要になってきている．そこで自験例を中心に^2)～8)，大腸癌のスクリーニング検査のあり方をめぐる2，3の問題点について述べてみたい．

　The age adjusted death rate from gastric cancer in Japan has decreased gradually since the peak in 1959. On the contrary, according to the change of our environmental factors, colon cancer has been increasing as among Americans and Europeans. Therefore, the screening system similar to gastric mass survey regime should be established as soon as possihle.

　There are several methods to detect colorectal cancer from asymptomatic people: questionaire as a screening filter of colon cancer, fecal occult blood test, sigmoidofiberscopy and so on. One of the most important techniques for the screening of colon cancer is the analysis of complaints caused by colon diseases. By analysis of questionaire responses, patients with colon cancer are easily differentiated from nomal subjects. However, patients with benign polyp and early cancer are not differentiated well from normal subjects. Fecal occult blood test is one of the most effective and simple methods of screening for colon cancer. However, there still exist false positives and negatives in this screening test and small and/or early lesions cannot be detected by fecal occult blood test alone. Endoscopic screening for the lower parts of the colon, most common sites of colon cancer, with flexible sigmoidofiberscope (TCFIS, CFHITS) are easily and effectively performed with minimal bowel preparation and without trouble to patients.

　Under evaluation of these screening techniques, a screening system for the early detection of colon cancer is proposed and it is desired that this screening system become as widely as gastric mass survey.