What do early bone scans tell about breast cancer patients?

In 1978, 1012 out of a total of 1888 Danish breast cancer patients registered for a nationwide therapeutical trial were bone-scanned to find osseous metastases. A re-reading group (N.R., O.M. and S.P.N.) interpreted 842 of the scans produced in the twelve participating hospitals. Specific criteria were used for grading the scintiscans. Of the 842 scans 682 were performed within 30 days of the operation and were defined as initial. The re-reading group found 50 (7%) of these scans to be equivocal and 46 (7%) to be indicative of bone metastases at the time of operation. The number of X-ray-verified bone metastases was only 5 (0.6%). The frequency of positive bone scans correlated with the age of the patients and tumor size, but not with clinical staging at the time of operation, number of positive axillary lymph nodes or degree of tumor anaplasia. Recurrences and death rates during a 2-yr follow-up period correlated significantly with initial clinical staging. In the clinical low-risk group a positive initial bone scan worsened the prognosis, but this was not statistically significant for all patients grouped together. Although the prognostic value of the initial bone scan per se is dubious, it serves as a guidance for elective X-ray examination and as a basis for comparing subsequent scans.