# Guidelines and variations in patterns of GnRH analogue use in castration-resistant prostate cancer across six countries

## TL;DR

This study examined how GnRH analogues are used in prostate cancer patients across six countries and found that a small number of patients stop using them, which may affect their survival.

## Contribution

The study provides real-world insights into the variability of GnRH analogue use and its impact on mortality in CRPC patients across different countries.

## Key findings

- A small proportion of CRPC patients across six countries discontinued GnRH analogues.
- Discontinuation was associated with higher mortality risk in Sweden.
- Variability in discontinuation patterns suggests differences in clinical practices or healthcare systems.

## Abstract

We investigated patterns of gonadotropin-releasing hormone (GnRH) analogue use in castration-resistant prostate cancer (CRPC) using real-world data from six countries.

Data were obtained from Guy’s and St Thomas’ NHS Foundation Trust (GSTT, UK), Prostate Cancer data Base Sweden (PCBaSe RAPID 2019, Sweden), Système National Des Données De Santé (SNDS, France), European Institute of Oncology (IEO, Italy), Ghent University Hospital (GUH, Belgium), and American University of Beirut Medical Center (AUB, Lebanon). Men diagnosed with CRPC between 2017 and 2019 were included in the study, with data extended to 2020 where available. Cox proportional hazards regression models were used to assess the effect of discontinuing GnRH analogues on overall mortality, adjusting for: age, Charlson Comorbidity Index (CCI), initial prostate cancer (PCa) treatment, and PCa risk group.

Out of 24 141 men with CRPC across the six countries, 1367 patients discontinued GnRH analogues. The discontinuation rates varied by country, with notable proportions from Sweden (338 men, 13%), France (1024 men, 5%), and Lebanon (5 men, 13%). Following adjustment for age, CCI, initial treatment for PCa, and PCa risk group, a higher risk of mortality in men who discontinued GnRH analogues was observed in Sweden (hazard ratio 2.30, 95% confidence interval 2.03-2.62).

Our study showed that although guidelines recommend the continued use of GnRH analogues in men with CRPC, a small proportion of men discontinue, the reasons for which are not fully understood. Further research is needed to explore potential contributing factors, such as differences in clinical practices, patient characteristics, or health care system across the countries studied.

•Differences in GnRH use may inform policy changes to improve patient outcomes.•The study aimed to evaluate treatment patterns in patients who continue or discontinue as prescribed.•Guidelines advise CRPC men to continue GnRH, a minority stop due to side-effects.•Variability in data sources made it difficult to define discontinuation accurately.•Variabilities were temporary/complete discontinuation or switch between GnRH types.

Differences in GnRH use may inform policy changes to improve patient outcomes.

The study aimed to evaluate treatment patterns in patients who continue or discontinue as prescribed.

Guidelines advise CRPC men to continue GnRH, a minority stop due to side-effects.

Variability in data sources made it difficult to define discontinuation accurately.

Variabilities were temporary/complete discontinuation or switch between GnRH types.