Bone Scan Index as a prognostic imaging biomarker during androgen deprivation therapy.
BACKGROUND
Bone Scan Index (BSI) is a quantitative measurement of tumour burden in the skeleton calculated from bone scan images. When analysed at the time of diagnosis, it has been shown to provide prognostic information on survival in men with metastatic prostate cancer (PCa). In this study, we evaluated the prognostic value of BSI during androgen deprivation therapy (ADT).


METHODS
Prostate cancer patients who were at high risk of a poor outcome and who had undergone bone scan at the time of diagnosis and during ADT were recruited from two university hospitals for a retrospective study. BSI at baseline and follow-up were calculated using an automated software package (EXINIbone(bsi)). Associations between BSI, other prognostic biomarkers and overall survival (OS) were evaluated using a Cox proportional hazards regression model.


RESULTS
One hundred forty-six PCa patients were included in the study. A total of 102 patient deaths were registered, with a median survival time after the follow-up bone scan of 2.4 years (interquartile range (IQR) =0.8 to 4.4). Both at baseline and during ADT, BSI was significantly associated with OS in univariate and multivariate analyses. When BSI was added to a prognostic base model including age, prostate-specific antigen, clinical tumour stage and Gleason score, the concordance index increased from 0.73 to 0.77 (p =0.0005) at baseline and from 0.77 to 0.82 (p <0.0001) during ADT.


CONCLUSIONS
Automated BSI during ADT is an independent prognostic indicator of OS in PCa patients with bone metastasis. It represents an emerging imaging biomarker that can be used in a prognostic model for risk stratification of PCa patients at the time of diagnosis and at later stages of the disease. BSI could then help physicians identify patients who could benefit from more aggressive therapies.
Division of Clinical Physiology and Nuclear Medicine, Department of Clinical Sciences, Skåne University Hospital, Malmö, Lund University, Inga Marie Nilssons gata 49, Malmö SE-205 02, Sweden.
Mariana
M
Reza
Division of Urological Cancers, Department of Clinical Sciences, Skåne University Hospital, Malmö, Lund University, Lund 22100, Sweden.
Anders
A
Bjartell
Department of Astronomy and Theoretical Physics, Lund University, Lund 22100, Sweden.
Mattias
M
Ohlsson
Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden.
Reza
R
Kaboteh
Division of Clinical Physiology and Nuclear Medicine, Department of Clinical Sciences, Skåne University Hospital, Malmö, Lund University, Inga Marie Nilssons gata 49, Malmö SE-205 02, Sweden.
Per
P
Wollmer
Division of Clinical Physiology and Nuclear Medicine, Department of Clinical Sciences, Skåne University Hospital, Malmö, Lund University, Inga Marie Nilssons gata 49, Malmö SE-205 02, Sweden ; Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, Gothenburg 413 45, Sweden.
Lars
L
Edenbrandt
Division of Clinical Physiology and Nuclear Medicine, Department of Clinical Sciences, Skåne University Hospital, Malmö, Lund University, Inga Marie Nilssons gata 49, Malmö SE-205 02, Sweden.
Elin
E
Trägårdh
Androgen deprivation therapy; Bone Scan Index; Bone metastases; Prostate cancer