Does a bone scan that shows a worsened appearance after chemotherapy portend a bad prognosis?
A bone scan that shows apparent worsening, as characterized by increased radiotracer activity in known lesions or the observation of new lesions, can be suggestive of progression of disease. However, the apparent worsening of prior bone scan abnormalities may also be associated with the “flare” phenomenon. The flare phenomenon results from increased osteoblastic activity in lesions associated with the bone’s healing response after chemotherapy. The flare response is associated with a good prognosis, suggesting effectiveness of the therapy. The flare response can occur 2-6 months after chemotherapy. A patient with a bone scan that shows apparent worsening abnormalities in this time period may receive another bone scan 4-6 months later to determine whether the lesions subsequently regress. If there is improvement on the latter scan, the previous scan can be considered to be related to a flare response associated with effective treatment.