The joint national cancer institute of canada/american cancer society study of a test for carcinoembryonic antigen (CEA)

The joint National Cancer Institute of Canada/American Cancer Society study of a test for carcinoembryonic antigen (CEA) was conducted in five University Centers in Canada and the United States with the Montreal General Hospital laboratory acting as the Reference Center. There were 503 patients admitted to the study, 146 with cancer of the colon or rectum. The results of the examination of specimens in four of the center laboratories correlated closely with those of duplicate halves examined in Montreal. Positive results (2.5 ng/ml CEA or more) in the Montreal laboratory occurred in 62% of the preoperative specimens from patients with colo‐rectal cancer, but in only 28% from patients with Dukes' A and B1 lesions, in 58% from Dukes' B2 and C1, and in 83% from C2. Positive results also occurred in 53% of specimens from patients with other cancers and in 29% from patients with other diagnoses. Although the test shows promise as a diagnostic aid for colorectal cancer, its lack of specificity precludes its use for screening. A 2‐year followup of all patients admitted to the study is being conducted.