Estimation of validity of mass screening program for gastric cancer in Osaka, Japan.

To assess the validity of mass screening tests for gastric cancer conducted with three types of radiographic techniques, i.e., photofluorography by a mirror camera, photofluorography by an image intensifier, and direct radiography, 105,122 persons who underwent a total of 272,667 screening tests during 1970 through 1982 were followed through December 31, 1983 by means of a record linkage to the Osaka Cancer Registry, Osaka, Japan. The results of 1 year's follow-up from screening were defined as the gold standard and test performance values were calculated. Sensitivity of screening with photofluorography by a mirror camera, photofluorography by an image intensifier, and direct radiography was 90%, 89%, and 91%, and specificity was 86%, 92%, and 91%, respectively. The receiver operating characteristics curve for screening with photofluorography by an image intensifier resembled that for direct radiography and these two curves were located somewhat to the left of the curve for screening with photofluorography by a mirror camera. The authors conclude that the validity of screening with photofluorography by an image intensifier is almost equivalent to that of screening with direct radiography and both are superior to that of screening with photofluorography by a mirror camera.