Blood-based LC-MS/MS analysis of steroids in prostate and ovarian cancer diagnostics

Abstract

This thesis addresses the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the analysis of sex steroids in castrated prostate cancer (PCa) patients and postmenopausal women. The study aims to develop and validate blood-based sex steroid LC-MS/MS assays and compare them to commonly used automated immunoassays (AIA). The study also investigates the potential clinical applications of these assays in advanced PCa patients and women undergoing oophorectomy. In Section 1, the development and validation of blood-based sex steroid LC-MS/MS assays are described. The protocol for the measurement of testosterone in human serum by LC-MS/MS is detailed, with a lower limit of quantitation (LLOQ) of 0.17 nmol/L and total imprecision of ≤ 4.7% coefficient of variation (CV). The biological variation (BV) of serum testosterone levels was estimated in PCa patients treated with chemical castration with or without enzalutamide, with a LLOQ of 0.025 nmol/L. An LC-MS/MS assay for the routine quantitation of estrone (E1) and estradiol (E2) in human serum was also developed and compared to an in-house E2 AIA, with sensitivity 10 times higher than the E2 AIA. In Section 2, testosterone analysis in PCa patients and its potential clinical applications are discussed. A literature review is provided on the history, current situation, and perspectives of testosterone analysis in PCa patients, with a focus on the strengths and shortcomings of different assay techniques. Potential clinical utilities are listed and evaluated, such as the predictive and prognostic value of testosterone analysis in hormone-sensitive and castration-resistant PCa patients. The review also highlights the importance of adequately reporting the analytical method in clinical trials. Section 3 of the thesis shifts the focus to the analysis of multiple sex steroids in women with a high risk of ovarian cancer. The study examines the relationship between changes in sex steroid levels and menopausal complaints in pre- and postmenopausal women undergoing risk-reducing salpingo-oophorectomy (RRSO). The results indicate that for premenopausal women, a decrease in estrogens is associated with a decrease in sexual functioning and for postmenopausal women, a decrease in testosterone is associated with a decrease in hot flash frequency. These findings suggest that steroid supplementation may have a role in mitigating symptoms in women experiencing menopausal complaints after RRSO. Overall, this section of the thesis highlights the importance of understanding changes in sex steroid levels in women undergoing RRSO and the potential implications for symptom management. The results of this thesis indicate that LC-MS/MS assays offer improved sensitivity and specificity compared to AIA, and have the potential to reveal new clinical applications in castrated PCa patients and postmenopausal women. However, further clinical studies are necessary to translate these results into practical changes in diagnostic practices. Additionally, the study emphasizes the importance of adequately reporting the analytical method in clinical trials.