Metabolic flare phenomenon on 18 fluoride-fluorodeoxy glucose positron emission tomography-computed tomography scans in a patient with bilateral breast cancer treated with second-line chemotherapy and bevacizumab

Increase in radiopharmaceutical uptake is an indicator of progression of disease. Paradoxical increase in the radiopharmaceutical uptake also occurs during favorable response to therapy, which is designated as flare phenomenon. Flare phenomenon is well documented on bone scinitgraphy when initially noted lesions show increased radiotracer uptake after therapy is instituted. This happens despite favorable response to the treatment. The osteoblastic activity associated with healing response of bone tumors is the cause of flare phenomenon. Recently, metabolic flare phenomenon has been described in patients with breast cancer who undergo hormonal therapy. Changes in the hormonal level during initial part of the treatment is the cause of metabolic flare. We describe a patient with bilateral breast cancer who underwent second line chemotherapy along with bevacizumab. Serial positron emission tomography scans done showed interesting phenomenon of metabolic flare.