Defining co-related parameters between ‘metabolic’ flare and ‘clinical’, ‘biochemical’, and ‘osteoblastic’ flare and establishing guidelines for assessing response to treatment in cancer

Excerpt

The success of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) in managing patients with cancer stems from its ability to monitor disease activity and predict treatment response early in the course of therapeutic interventions, which appears superior to that of anatomic modalities. A plethora of therapeutic choices are now available to oncologists, and, therefore, early assessment of treatment response will help not only in making appropriate therapy modifications but also in minimizing treatment-related toxicity. Selection of appropriate timing for post-therapy FDG-PET imaging in relation to the administered therapy has been a major source of uncertainty with regard to the reliability of early assessment of tumor response using FDG-PET. While this has been discussed and highlighted in a number of editorials and review articles [1‐4], there continues to be a paucity of carefully conducted prospective studies to resolve the issue. Herein, we discuss and classify the various patterns and mechanisms for metabolic flare reported in the FDG-PET literature and endeavor to compare and contrast these with other forms of flare described in clinical oncology parlance, viz. the osteoblastic flare in skeletal scintigraphy, the clinical symptomatic flare, and the biochemical flare of tumor markers, through a critical analysis of existing literature. …