Bone metastases in primary operable breast cancer. The role of serial scintigraphy

In 1978 and 1979, 1060 Danish patients with primary operable breast cancer were bone-scanned for osseous metastases before entering a nationwide therapeutical trial. A re-reading group interpreted the scans produced in 12 participating hospitals. As a consequence standardized guide-lines for interpretation were agreed upon from 1979. The frequency of positive bone scans suggesting bone metastases fell abruptly from 1978 to 1979, as read both locally and by the re-reading group. As measured statistically the difference between the interpretation of the local and the re-reading groups remained unchanged. Of the 1060 patients 760 were followed by repeated pre-scheduled scans 6 and 12 months after surgery until any kind of recurrence was diagnosed. Only 37 of the 760 patients (4.9%) developed bone metastases verified by radiology or autopsy during the first 2 yr after surgery. A single positive scan, especially performed 6 or 12 months after surgery, as well as two or three scans repeatedly staying or becoming positive increase significantly the risk of developing bone metastases within 12 months after the latest scan. In 13 of the 37 patients with otherwise subsequently proven bone metastases the latest scan(s) were negative. It is concluded that a fixed schedule of repeated bone scans in patients with breast cancer is not warranted.