predictive value of serial bone scan in assessing response to chemotherapy in advanced breast cancer

ABSTRACT

Changes in osteoblast function assessed by serial bone scans have been studied in 50 patients receiving systemic chemotherapy [FAC or Taxol] for bone metastases from advanced breast cancer. All patients had baseline scans prior to therapy after the 3rd cycle, after the 6th cycle and then every three months during the follow-up period of the study [ranged 14-27 months]. Thirteen patients had a flare response following the 3rd cycle of chemotherapy characterized by increased activity in baseline lesions and the appearance of new foci of tracer uptake changes which are indistinguishable from progressive disease. These changes are attributed to a flare in osteoblastic activity induced by successful systemic therapy. After six months of successful treatment, the bone scan improved with reduced traces uptake and no new lesions since the 3rd month scan. New lesions appearing after the 6th month indicated progressive disease. Flare on bone scintigraphy may be seen shortly after commencing chemotherapy. Bone scans done within the first three months must be interpreted with caution and should be correlated with clinical and radiological findings to avoid inappropriate discontinuation of chemotherapy