Androgen deprivation monotherapy usage in non-metastatic prostate cancer: results from eight European countries

Introduction

The aim of this study was to investigate the attitudes towards use of androgen deprivation therapy (ADT) as monotherapy for localized or locally advanced prostate cancer (PC).

Material and methods

A survey using a 28-item, structured, quantitative questionnaire about the management of patients with PC was conducted in eight European countries between February and May 2018. Survey recipients were selected from a private database of healthcare providers.

Results

Overall, 375 physicians completed the survey (response rate, 58%). Participants were urologists (71.2%) or medical oncologists (28.8%), with a mean practice duration of 19.9 years and with university hospital or cancer center (41.6%), non-teaching hospital (38.4%) or private-sector clinic (20.0%) affiliations. Median proportions of physicians considering ADT as monotherapy to treat patients with PC in different risk groups varied between countries, but overall were: high/very high-risk, 60%; intermediate-risk, 30%; low-risk, 7.5%. The use of ADT monotherapy in the different risk groups also varied by medical specialty and type of affiliation. Proportions of participants applying different target thresholds for testosterone (T) levels also varied by country, but overall were: <50 ng/dL, 29.9%; <32 ng/dL, 4.8%; <20 ng/dL, 54.3%; castration but no specific target, 11%. More than half of participants (58.7%) determined target T levels only when prostate-specific antigen level was increased.

Conclusions

Our multinational survey provides evidence that PC management varies across European countries and with clinical context, and frequently diverges from European Association of Urology (EAU) - European Society for Radiotherapy and Oncology (ESTRO) - European Society of Urogenital Radiology (ESUR) - International Society of Geriatric Oncology (SIOG) guidelines. Strategies for effective implementation of evidence-based recommendations in clinical practice may be needed to optimize patient outcomes.

Tissue culture media supplemented with 10% fetal calf serum contains a castrate level of testosterone

BACKGROUND

Human prostate cancer cells are routinely maintained in media supplemented with 10% Fetal Calf Serum (FCS) to provide androgen. In the present study, total and free testosterone levels in 10%FCS supplemented tissue culture media were determined and compared to levels in intact and castrated human males. Dextran-coated charcoal stripped FCS (i.e., DC-FCS) is often used instead of FCS to minimize the level of androgen provided in 10% serum supplemented media. Therefore, total and free testosterone levels in 10%DC-FCS containing media were likewise determined.

METHODS

Total testosterone, free testosterone, and total dihydrotestosterone (DHT) were determined on RPMI-1640 media supplemented with either 10%FCS or 10%DC-FCS by ELISA assays before and after exposure to LNCaP human prostate cancer cells in culture. The growth and PSA secretion by these cells was also determined.

RESULTS

Ten percentage FCS supplemented media contains a castrate level of testosterone. However, even with this castrate starting level of testosterone, LNCaP cells concentrate and metabolize the testosterone to produce a physiologic (i.e., 10 nM) level of intracellular DHT which optimally stimulates the growth of these cells in vitro.

CONCLUSIONS

The present studies document that prostate cancer cells auto-regulate their androgen metabolism so that an optimal level of DHT for growth is maintained during both up and down fluctuations in the supply of testosterone. These results have significant implications for whether exogenous androgen should be added to the 10%FCS supplemented media to grow prostate cancer cells from intact versus castrated patients.