Baseline 18F-FDG PET/CT parameters as imaging biomarkers of overall survival in castrate-resistant metastatic prostate cancer - Abstract

The aim of this prospective investigation was to assess the association of parameters derived from baseline 18F-FDG PET/CT with overall survival (OS) in men with castrate-resistant metastatic prostate cancer.

METHODS: Eighty-seven men with castrate-resistant metastatic prostate cancer underwent 18F-FDG PET/CT and were followed prospectively for OS. Median follow-up in patients who were alive was 22.2 mo (range, 1.6-62.5 mo). OS was defined as the time between the PET/CT imaging or the start of chemotherapy, whichever was later, and death, with patients who were alive censored at the last follow-up date. PET parameters included maximum standardized uptake value (SUVmax) of the most active lesion, sum of SUVmax, and average SUVmax of all metabolically active lesions, after subtraction of patient-specific background-liver average SUV. Comparison of OS was based on univariate and multivariable Cox regression analyses of continuous PET parameters adjusted for standard clinical parameters (age, serum prostate-specific antigen level, alkaline phosphatase, use of pain medication, prior chemotherapy, and Gleason score at initial diagnosis). Survival curves based on Kaplan-Meier estimates are presented.

RESULTS: Among the 87 patients, 61 were dead at the time of last follow-up. Median OS was 16.5 mo (95% confidence interval [CI], 12.1-23.4 mo), and the OS probability at 24 mo was 39% ± 6%. For the univariate analysis, the hazard ratios associated with each unit increase were 1.01 (95% CI, 1.006-1.02) for sum of SUVmax (P = 0.002), 1.11 (95% CI, 1.03-1.18) for maximum SUVmax (P = 0.010), and 1.13 (95% CI, 0.99-1.30) for average SUVmax (P = 0.095). For the multivariable analysis adjusting for relevant clinical parameters, the continuous parameter sum of SUVmax remained significant (P = 0.053), with a hazard ratio of 1.01 (95% CI, 1.001-1.02). When sum of SUVmax was grouped into quartile ranges, there was poorer survival probability for the patients in the fourth-quartile range than for those in the first-quartile range, with a univariate hazard ratio of 3.8 (95% CI, 1.8-7.9).

CONCLUSION: Sum of SUVmax derived from 18F-FDG PET/CT contributes independent prognostic information on OS in men with castrate-resistant metastatic prostate cancer, and this information may be useful in assessing the comparative effectiveness of various conventional and emerging treatment strategies.

Written by:
Jadvar H, Desai B, Ji L, Conti PS, Dorff TB, Groshen SG, Pinski JK, Quinn DI.   Are you the author?
Division of Nuclear Medicine, Department of Radiology, Keck School of Medicine of USC, University of Southern California, Los Angeles, California.

Reference: J Nucl Med. 2013 Jun 19. Epub ahead of print.
doi: 10.2967/jnumed.112.114116

PubMed Abstract
PMID: 23785174