Testosterone analysis in castrated prostate cancer patients: suitability of the castration cut-off and analytical accuracy of the present-day clinical immunoassays

OBJECTIVES

Testosterone testing is relevant for evaluating castration adequacy and diagnosis of castration-resistant prostate cancer (PCa). However, the recommended testosterone cut-off of 1.7 nmol/L (50 ng/dL) to define adequate castration is based on consensus and not validated for the automated immunoassays (AIA) used in today's medical laboratories. Furthermore, appropriate population intervals have not been determined by a state-of-the-art assay. We investigated the analytical suitability of this cut-off and the accuracy of the present-day AIAs for testosterone analysis in castrated PCa patients.

METHODS

Leftover serum from 120 PCa patients castrated with luteinizing hormone-releasing hormone agonists was analysed for testosterone by five methods: Architect i2000 (Abbott), Access (Beckman), Cobas 6000 (Roche), Atellica (Siemens), LC-MS/MS. For all assays, the castration 95th, 97.5th and 99th percentile upper limits were determined. Furthermore, Passing-Bablok regression, mean bias and Spearman's correlation coefficients were compared to the LC-MS/MS method and total error based on biological variation.

RESULTS

All castration upper limits, ranging from 0.472 nmol/L (LC-MS/MS) to 1.25 nmol/L (Access) (95% percentile), were significantly lower than the current castration cut-off (1.7 nmol/L). Slopes of Passing-Bablok regressions comparing the AIA with the LC-MS/MS method ranged from 1.4 (Cobas and Atellica) to 3.8 (Access). The Architect showed the highest correlation with LC-MS/MS (ρ=0.58). All AIA failed to meet the desirable total error criterion.

CONCLUSIONS

These results suggest that a lower general testosterone castration cut-off may be more appropriate in evaluating the adequacy of castration in PCa and that present-day AIA lack analytical accuracy to quantify testosterone levels in castrated PCa.

Testosterone analysis in prostate cancer patients

Testosterone is an essential steroid hormone associated with a wide variety of biological processes in humans. In prostate cancer, androgen signaling is an important driver of tumor cell growth. Depletion of gonadal testosterone, achieved by surgical or chemical castration, prevents androgenic signaling and temporally reduces, stops or reverses tumor growth before inevitable progression to castration-resistant prostate cancer occurs. Additional treatment strategies targeting androgenic signaling have become available, although these are without curative intent. While circulating testosterone is also associated with disease risk and potential clinical utility, the main use in the clinical lab is monitoring adequate castration and subsequent resistance to therapy. Adequate castrate testosterone concentrations are currently based on over 50 year-old double-isotope derivative assays that are disputed in automated immunoassay (IA) analysis. The debate has been further fueled with the introduction of mass spectrometry-based assays for testosterone, offering a substantial increase in sensitivity and specificity. In this review, we discuss testosterone regulation and androgen deprivation therapy in prostate cancer. We provide an overview of the developments in testosterone analysis for monitoring adequate castration and resistance to therapy. Current clinical practice and future clinical utility will be discussed. Finally, clinical and research recommendations will be presented.

Changes in Sex Steroids and relation with Menopausal Complaints in Women Undergoing Risk-Reducing Salpingo-Oophorectomy

Context

Risk-reducing salpingo-oophorectomy (RRSO) is performed in BRCA1 or 2 mutant carriers to minimize ovarian cancer risk. Although studies have been performed investigating sex steroid levels, menopausal complaints, and sexual functioning in relation to RRSO, their exact relationship remains unknown.

Objectives

To investigate the impact of RRSO on serum sex steroid levels and their association with menopausal complaints and sexual functioning.

Methods

This prospective observational cohort study included 57 premenopausal and 37 postmenopausal women at risk of ovarian cancer and opting for RRSO. Data collection involved validated questionnaires on sexual functioning and menopausal complaints. Testosterone, androstenedione, estradiol, and estrone levels in serum determined by liquid chromatography-tandem mass spectrometry were obtained 1 day before, 6 weeks, and 7 months after RRSO.

Results

In premenopausal women, all 4 steroids were decreased both 6 weeks (P < 0.01) and 7 months (P < 0.01) after RRSO. Furthermore, in these women, decreases in estrogens were associated with a decrease in sexual functioning 7 months after RRSO (P < 0.05). In postmenopausal women, only testosterone was decreased 6 weeks and 7 months (P < 0.05) after RRSO, which was associated with an increase in menopausal complaints at 7 months post-RRSO (P < 0.05).

Conclusion

Our results suggest that in premenopausal women, decreases in estrogens are related to a decrease in sexual functioning and that in postmenopausal women, testosterone is decreased after RRSO, which indicates that postmenopausal ovaries maintain some testosterone production. Furthermore, in postmenopausal women, a large decrease of testosterone was associated with more menopausal complaints, indicating that future studies investigating testosterone supplementation are warranted.

Retrospective analysis of serum testosterone levels by LC-MS/MS in chemically castrated prostate cancer patients: Biological variation and analytical performance specifications

BACKGROUND

A sensitive liquid chromatography tandem-mass spectrometry (LC-MS/MS) method was used to monitor serum testosterone levels in castrated prostate cancer patients. We subsequently performed an observational and retrospective study to estimate the within- and between-subject biological variation of these patients.

METHODS

In total, 474 samples from 72 prostate cancer patients in the Netherlands receiving either chemical castration (CAS) or castration plus enzalutamide (ENZA) treatment were selected for data analysis. ANOVA was performed to estimate analytical variation (CV_A) and within-patient variation (CV_I). A nested ANOVA was applied to estimate between-patient variation (CV_G). From these data, the reference change value (RCV) and analytical performance specifications (APS) were calculated.

RESULTS

Testosterone levels were significantly higher in the ENZA group (0.318 vs. 0.191 nmol/L, p < 0.005) than the CAS group. Overall, variation components were estimated at 6.1%, 24.6% and 60.3% for CV_A, CV_I and CV_G, respectively. Both groups showed high individuality (<0.6). The RCV was 70.3% for all patients. Desirable APS were 12.3% for imprecision, 16.3% for bias and 26.4% for total error.

CONCLUSION

The generated APS are valuable for sensitive testosterone assays and the high individuality indicates that castrated testosterone levels can be studied as a predictive or prognostic biomarker in prostate cancer patients.