Monitoring testosterone (T) levels is recommended to assess the effectiveness of androgen deprivation therapy (ADT) in advanced prostate cancer. T levels below 20 ng/dL have been associated with better outcomes.
Three main measures for T exist including radioimmunoassay (RIA), chemiluminescence assay (CLIA) and mass spectrometry (MS). While CLIA and RIA are ubiquitous, MS is regarded as the reference standard. We set out to determine the discordance of T measurements amongst men on ADT.
A retrospective review of men with prostate cancer on ADT for ≥3 months was conducted. Serum samples were split in triplicate. Observational data was reported and T measurements were compared analyzing for variability looking for categorical concordance. Over and under-estimation rates were calculated.
Ninety-five patients were included with a mean age of 70 (50-92) years. Mean ADT duration was 24.1 (3-144) months. Ninety-five percent of patients had T ≤20ng/dL by MS and CLIA as compared to only 80% by RIA. After subdividing into T categories of ≤20, 20 to 50 and ≥50 ng/dL concordance analysis showed that 4.3% and 18.9% of T measured by MS would have a different category result when remeasured by CLIA (Kappa 0.84) or RIA (Kappa 0.50) respectively. CLIA and RIA overestimated T in 66.7% of patients with T <20 ng/dL measured by MS. Conversely CLIA and RIA underestimated T in only 4.4% of cases with T >20 ng/dL measured by MS.
There is significant variability in T measured with RIA, CLIA and MS. CLIA and RIA overestimated T levels in majority of patients leaving a concern of misdiagnosing truly castrate patients as being inadequately treated.
Urologic oncology. 2022 Apr 15 [Epub ahead of print]
Raj Tiwari, Katherine Lajkosz, MohamadBaker Berjaoui, Yazan Qaoud, Miran Kenk, Clive Woffendin, Patrick Caron, Chantal Guillemette, Neil Fleshner
Division of Urology, Department of Surgery, University of Toronto, Toronto, ON, Canada. Electronic address: ., Division of Urology, Department of Surgery, University of Toronto, Toronto, ON, Canada; Department of Biostatistics, Princess Margaret Cancer Center, Toronto, ON, Canada., Division of Urology, Department of Surgery, University of Toronto, Toronto, ON, Canada., Oregon Clinical and Translational Research Institute at Oregon Health and Science University (OHSU), Portland, OR., Pharmacogenomics Laboratory, Centre Hospitalier Universitaire (CHU) de Québec, Université Laval Research Center and Faculty of Pharmacy, Université Laval, Québec city, QC, Canada.
PubMed http://www.ncbi.nlm.nih.gov/pubmed/35437219