Dependence of the specificity of the serologic test for primary liver cancer in different areas of the world on sensitivity of the method used for detecting alpha‐fetoprotein

Abstract

Abstract A comparative investigation was made of the diagnostic value of the AFP test as dependent on sensitivity of the method used for detecting AFP. Patients' sera, collected from five African countries, from Singapore, Jamaica, and the USSR, and checked earlier by the standard AFP test (agar‐gel precipitation technique) were reexamined using the method of indirect immunoradioautography. The latter method is 30 to 50 times more sensitive than the standard AFP test. As a result the percentage of hepatomas revealed serologically was increased for Africa from 75% to 89.2% and for the USSR from 64% to 87.1% (among histologically proven cases). The diagnostic specificity of the test became significantly lower: a great number of AFP‐positive cases was observed in the control group. The proportion of such “false‐positive” cases is not equal in different parts of the world: 22.6% in Africa and 6.0% in the USSR. Great differences were also observed between African countries, from 7.8% in Uganda to 45.1% in Congo. It is suggested that these variations are related to the existence of a “background” AFP level in healthy people, which may be different in various populations depending on genetic and nutritional factors. The differences may be a reflection of varying predisposition to cancer of the liver.