Approaches for assessment of response of bone metastases to therapies

Abstract

The recent introduction of new therapeutic agents has proven alternative options in the management of patients with metastatic castration-resistant prostate cancer (mCRPC). Moreover, other novel agents are being studied and developed. Bone represents the most common site of recurrence in mCRPC, occurring in more than 80 % of cases. The evaluation of treatment efficacy in bone metastatic prostate cancer (PC) is mainly focused on the assessment of patient outcomes, but the behavior of bone metastases and their changes due to the therapy are also of great interest. The impressive development of technologies offers today various options for describing the skeletal changes caused by metastases before, during, and after treatments. At present, in clinical practice, the only laboratory test currently used to measure metastatic bone progression remains prostate-specific antigen (PSA). Great importance has been progressively assumed by new modalities of metabolic imaging, such as 18F fluoride, 18F/11C choline, and 18F FDG positron emission tomography (PET)/computed tomography (CT) that are flanking the traditional bone scan (BS) with 99mTc phosphonates, both with planar acquisition and single-photon emission computed tomography (SPECT). In addition, radiology, besides CT, is proposing the high performance of multimodality magnetic resonance imaging (MRI) that seems to guarantee a very high accuracy in evaluating skeletal involvement.