Abstract
To assess the validity of mass screening tests for cancer, 431,899 screenees for gastric cancer and 213,978 screenees for colorectal cancer from 1996 through 2002 were followed up until December 31, 2003 and their data were matched with that of the Osaka Cancer Registry. The sensitivity and specificity of the screening tests for stomach cancer were estimated to be 93.2% and 90.7% respectively. And those for colorectal cancer were estimated to be 96.5% and 96.0% respectively.
