Radiographic progression-free survival (rPFS) by Prostate Cancer Working Group (PCWG) criteria is a radiographic endpoint. The automated bone scan index (aBSI) quantifies osseous disease burden on bone scintigraphy as a percentage of total skeletal weight. Using the aBSI, we sought to quantify increase in tumor burden represented by PCWG progression criteria, and to determine the interval increase that best associates with overall survival (OS).
Retrospective analysis of trials using androgen receptor axis-targeted drugs for metastatic castration resistant prostate cancer patients (mCRPC). aBSI increase in bone disease was assessed from baseline scan to time-to-progression (per PCWG criteria). Threshold for time to aBSI increase were explored and the association between each time-to-threshold and OS was computed.
A total of 169 mCPRC patients had bone scans available for aBSI analysis. Of these, 90 (53%) had progression in bone meeting PCWG criteria. Total aBSI increase in patients meeting PCWG criteria was 1.22 (interquartile range [IQR]: 0.65-2.49), with a median relative increase of 109% (IQR: 40%-377%). Median aBSI at baseline was 3.1 (IQR: 1.3-7.1). The best association between OS and time-to-progression occurred with an absolute increase in aBSI equal to 0.6 (Kendall's tau 0.52).
An absolute increase of 0.6 or more in aBSI from the first follow-up scan results in the highest association with OS in patients with mCRPC. The rPFS by PCWG, identified progression at nearly twice this tumor burden, suggesting that aBSI may be used to further develop the PCWG criteria without degrading its association with OS.
Clinical genitourinary cancer. 2022 Feb 09 [Epub ahead of print]
Aseem Anand, Glenn Heller, Joseph Fox, Daniel C Danila, Anders Bjartell, Lars Edenbrandt, Steven M Larson, Howard I Scher, Michael J Morris
Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY; Department of Translational Medicine, Division of Urological Cancers, Malmö, Lund University, Lund, Sweden., Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY., Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY., Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY; Weill Cornell Medical College, New York, NY., Department of Translational Medicine, Division of Urological Cancers, Malmö, Lund University, Lund, Sweden., Department of Clinical Physiology, Sahlgrenska University Hospital, Gothenburg, Sweden; Department of Clinical Physiology, Skåne University Hospital, Lund University, Malmö, Sweden., Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY; Weill Cornell Medical College, New York, NY., Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY; Weill Cornell Medical College, New York, NY. Electronic address: .