The application of the 99Tcm phosphate bone scan to the study of breast cancer.

Comparison of the gamma camera bone scan and radiological survey in 190 patients with breast cancer has confirmed the superiority of the bone scan in the positive diagnosis of skeletal metastases. In 47 patients with known (X-ray positive) bony metastases the scan was positive in all but 2, and in 24 (50 per cent) the scan showed more lesions than the X-ray had indicated. In 60 patients with a clinical suspicion of bone metastases but negative X-rays, the scan was positive in 29 (48 per cent). Eighty-three patients with primary breast cancer were studied at the time of initial presentation. All had a normal radiographic skeletal survey but 24 (27 per cent) had scan evidence of occult metastases. It is concluded that a bone scan is indicated in all patients with breast cancer where skeletal metastases are suspected. Repeated bone scans may introduce new therapeutic possibilities, by providing an earlier objective index of progression of metastatic disease and also by providing a quantitative method of assessing the response to therapy.