CAN delayed diagnosis and treatment of breast tumors be avoided by periodic x-ray examinations of women over 40 years of age? The results of a 5-year study, reported and interpreted here, indicated "yes." Since January, 1956, a program for routine examination of the breast for the detection of cancer has been conducted as a separate unit in the Radiology Department of the Albert Einstein Medical Center.1Appeals for volunteers were made to local civic and social organizations of women. There was but one stipulation—that any candidate wishing to participate in the program be free of breast symptoms. All x-ray examinations in the survey were provided without cost to the volunteer. During this time we enlisted 1,312 women. At present 1,055 women still remain in the program; 257 dropped out after one or more examinations. Each volunteer is examined every 6 months. At the initial examination each volunteer is