Gonadotropin-releasing Hormone Agonists, Orchiectomy, and Risk of Cardiovascular Disease: Semi-ecologic, Nationwide, Population-based Study

BACKGROUND: In observational studies, men with prostate cancer treated with gonadotropin-releasing hormone (GnRH) agonists had a higher risk of cardiovascular disease (CVD) compared to men who had undergone orchiectomy. However, selection bias may have influenced the difference in risk. OBJECTIVE: To investigate the association of type of androgen deprivation therapy (ADT) with risk of CVD while minimising selection bias. DESIGN, SETTING, AND PARTICIPANTS: Semi-ecologic study of 6556 men who received GnRH agonists and 3330 men who underwent orchiectomy as primary treatment during 1992-1999 in the Prostate Cancer Database Sweden 3.0. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We measured the proportion of men who received GnRH agonists as primary treatment in 580 experimental units defined by healthcare provider, diagnostic time period, and age at diagnosis. Incident or fatal CVD events in units with high and units with low use of GnRH agonists were compared. Net and crude probabilities were also analysed. RESULTS AND LIMITATIONS: The risk of CVD was similar between units with the highest and units with the lowest proportion of GnRH agonist use (relative risk 1.01, 95% confidence interval CI 0.93-1.11). Accordingly, there was no difference in the net probability of CVD after GnRH agonist compared to orchiectomy (hazard ratio 1.02, 95% CI 0.96-1.09). The 10-yr crude probability of CVD was 0.56 (95% CI 0.55-0.57) for men on GnRH agonists and 0.52 (95% CI 0.50-0.54) for men treated with orchiectomy. The main limitation was the nonrandom allocation to treatment, with younger men with lower comorbidity and less advanced cancer more likely to receive GnRH agonists. CONCLUSION: Our data do not support previous observations that GnRH agonists increase the risk of CVD in comparison to orchiectomy. PATIENT SUMMARY: We found a similar risk of cardiovascular disease between medical and surgical treatment as androgen deprivation therapy for prostate cancer.