Gastroenterologia Japonica Copyright 9 1988 by The Japanese Society of Gastroenterology Vol. 23, No. 1 Printed in Japan ABSTRACTS OF SELECTED PAPERS PRESENTED AT THE 73RD GENERAL MEETING OF THE JAPANESE SOCIETY OF GASTROENTEROLOGY Tokyo, Japan, April 7-9, 1987 Chairman : Shinroku ASHIZAWA, M. D. Symposium-1 New fecal occult blood testing for colorectal cancer Moderators: Tsuneyoshi YAO and Tetsuichiro MUTO Method of mass screening for colorectal cancer --an immunological fecal occult blood test Hidenori NAKAMA Nagano Prefectural Cancer Examination Center In order to establish the method of mass screen- ing for colorectal cancer, a new immunological fecal occult blood test, FECA-EIA, Labosys- tems, Co., was evaluated. Fecal occult blood testing was performed in 49 patients with advanced colorectal cancer, 39 patients with early colorectal cancer, 78 patients with adenoma and 166 normal Subjects. The high sensitivity and specificity of FECA- EIA to colorectal cancer was demonstrated. The usefullness of FECA-EIA was also showed on further study under field condition with 8089 population. It is concluded that FECA-EIA has great potential for mass screening of colorectal cancer, the improvement of the cost-benefit ratio and the complexity of the technique is expected. An immunologic test for fecal occult blood by reversed passive hemagglutination for mass screening of colorectal cancer. Hiroshi SAITO and Ryosuke KAKIZAKI First Department of Internal Medicine, Hirosaki University School of Medicine. We have developed a new sensitive and simple immunologic occult blood test employing reversed passive hemagglutination (RPHA). In normal controls RPHA titre was less than 22, which was equivalent to 0.1-0.2 mgHb/g feces. In 72 specimens from 36 patients with colorectal cancer, RPHA and Hemoccult test (HO) were positive in 86% and 47%, respectively (p<0.01). Positive RPHA results were obtained in 93% of ulcerated cancers, i.e. Borrmann 2 or 3 type. Positive rates of RPHA were increased with the size of tumor and 98% of cancers larger than 3 cm in diameter gave positive results in RPHA. In adenomas, positive rates of RPHA were also increased with size. Positive RPHA results were obtained in 23% of 44 polyps of 6 to 9 mm in size, whereas only in 1% of 85 polyps less than 5 mm. Polyps of 10 to 19 mm in size and those larger than 20 mm gave positive rates of 59% and 73%, respectively. Of 14 patients with polyps showing positive RPHA results, all gave negatives after polypectomy. 1,712 persons were screened for colon cancer by single RPHA and single HO. Colon cancers were detected in 2 and polyps in 8 of 16 FPHA positives. There were 16 small polyps but no cancer in 116 HO positives. In another screening program for colon cancer in 3,856 participants, single RPHA testing detected 3 cancers which 3-day HO failed to. Thus, single RPHA was shown to be more sensitive than 3-day HO for detection of colorectal cancer. We have screened 34,868 per- sons for colorectal cancer using RPHA since 1983. RPHA showed positive results in 2.8% of