ORLANDO, FL, USA (UroToday.com) - Castrate-resistant prostate cancer is usually associated with high incidence of osseous metastasis. While imaging allows treatment response in the soft tissue metastasis to be measured, its application in bony metastasis is limited. Quantitative total bone imaging (QTBI) is an innovative tool that may allow the treatment response to be measured using functional attributes of 18F-Sodium Fluoride (NaF) PET/CT. The group reports on a multi-center trial assessing the performance characteristics and responsiveness of QTBI as an imaging biomarker of treatment response in men with metastatic castrate-resistant prostate cancer to bone, treated with either taxane-based or androgen-receptor directed treatment.
Fifty-four patients have been enrolled. All subjects underwent 18F-Sodium Fluoride (NaF) PET/CT at baseline and again at 8 weeks after treatment with taxane-based therapy or at both 6 weeks and 12 weeks after starting androgen-receptor directed treatment. The aim was to assess response to treatment.
Changes in SUVmax, SUVtotal, and SUVmean reflect quantifiable PET measurements that are complementary but may have different meaning depending on the treatment administered (cytotoxic vs cytostatic). Relying on one measure alone can be misleading, particularly when assessing treatment response. For example, some lesions may experience a decrease in SUVmax, while simultaneously having an increase in SUVtotal. This implies that the therapy decreased the max functional activity of the lesion, but the overall functional burden of the lesion increased analogous to “slowing down” progression. This is in contrast with lesions that decrease (increase) in both SUVmax and SUVtotal, which would imply decreased activity and burden (increased activity and burden).
In summary, QTBI provides a unique tool in understanding the dynamics of treatment response, allowing newer trial designs that can explore combination, sequence, and the issue of continuing treatment, beyond progression, with existing therapies.
Presented by Glenn Liu, Scott Perlman, Tim Perk, Stephanie Harmon, Kelly Simmons, Mary Jane Staab, and Robert Jeraj at the 2015 Genitourinary Cancers Symposium - "Integrating Biology Into Patient-Centric Care" - February 26 - 28, 2015 - Rosen Shingle Creek - Orlando, Florida USA
University of Wisconsin Carbone Cancer Center, Madison, WI; Department of Radiology, University of Wisconsin, Madison, WI; University of Wisconsin, Madison, WI; Department of Medical Physics, University of Wisconsin, Madison, WI
Reported by Mohammed Haseebuddin, MD, medical writer for UroToday.com