Metabolically active tumor volume (MATV) measurements can be applied to (18)F-fluorocholine positron emission tomography/computed tomography (PET/CT) to quantify whole-body tumor burden. This study evaluates the serial application of these measurements as systemic treatment response markers and predictors of disease progression in patients with castrate-resistant prostate cancer (CRPC).
METHODS - Forty-two patients completed sequential (18)F-fluorocholine PET/CT scans before and 1 to 3 months after starting treatment for CRPC. Whole-body tumor segmentation was applied to determine net MATV from each scan. Changes in net MATV were evaluated as predictors of time to PSA progression by Kaplan-Meier and proportional hazards regression analysis.
RESULTS - Treatments consisted of chemotherapy in 16 patients, anti-androgens in 19 patients, (223)Ra-dichloride in 5 patients, and sipuleucel-T in 2 patients. A significant MATV response (defined as a 30% or greater decrease in net MATV) was observed in 20 patients based on in-treatment PET/CT performed an average (median) of 52 (49) days into treatment. Significantly longer times to PSA progression were observed in patients that exhibited a MATV response (418 days vs. 116 days, P = 0.007). MATV response was associated with a hazard ratio of 0.246 (P = 0.01116) for PSA progression, which remained significant when adjusted for treatment type.
CONCLUSIONS - Significant changes in whole-body tumor burden can be measured on (18)F-fluorocholine PET/CT over the course of contemporary treatments for CRPC. In this study, these changes were found to be predictive of PSA progression as a potential surrogate marker of treatment outcome. Because (18)F-fluorocholine PET/CT can also be used for localizing resistant tumors, this modality can potentially complement other measures of response in the precision management of advanced prostate cancer.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2016 Feb 16 [Epub ahead of print]
Joo Hee Lee, Miles Sato, Marc N Coel, Kyung-Han Lee, Sandi Kwee
Samsung Medical Center, Korea, Republic of;, The Queen's Medical Center, United States;, The Queen's Medical Center, United States;, Sungkyunkwan University School of Medicine, Korea, Republic of., The Queen's Medical Center, United States;