Mammography as a Screening Examination In Breast Cancer

DOUTINE mammography was performed ft as a screening test for cancer in 3,891 women at a cancer detection clinic. On careful physical examination the breasts were considered normal, but 16 carcinomas were discovered and proved, a rate of 4.11 per 1,000. In 14 of these 16 cases (87.5 per cent), no evidence of metastatic disease was found in the axilla at the time of mastectomy, and an improved prognosis resulted. The roentgenographic examination is easily performed and interpreted, and these findings illustrate the frequency with which carcinoma in an early stage is missed by routine physical examination. Material The women attended the Yates Cancer Detection Clinic voluntarily and represented all economic and racial group.s of the Detroit metropolitan area. The physical examinations were performed by members of the Faculty of Wayne State University School of Medicine. Admittance to the study required that the subjects be forty-six years of age or more and asymptomatic as to breast disease; the breast must be normal on physical examination. Seventy per cent of the patients were between forty-six and sixty years old (Table I); 75 per cent were postmenopausal (Table II). Previous biopsies had been obtained in 8.35 per cent, and in 7.5 per cent there was a family history of breast cancer. The examining physicians were informed of the study and asked to be particularly careful in performing the examination. In addition, with the intention of maintaining their constant alertness, each time an occult cancer was found and proved, this fact was publicized. All mammography was performed at the Woman's Hospital with the lowkilovoltage technic described by Egan (1), with a few changes thought to offer advantages (Table III). An axillary view was not made as a separate exposure; the film for the lateral projection was placed to include the axilla as well as the breast. A long flat-sided cone was employed because with it efficient collimation limited the x-ray beam to the breast and the technician was helped in positioning the patient. The parts to be examined vary in thickness so that a good film of the anterior third of the breast frequently results in an underexposed chest wall or axilla. To permit adequate filming with only one exposure, two films of varying speeds—DuPont #506 and 510 or Eastman Kodak type M and AA—were employed simultaneously, one on top of the other. Dosimetry studies revealed an average of 3..5 to 4.5 rads at the entrance ports for the total examination; the dosimeters were left in place for both views (6). Roentgen Diagnosis In reading the films, the diagnosis was given as malignant, suspicious, benign, or normal. The rates of occurrence are tabulated in Table IV.