Patient preference on once-daily oral versus injectable androgen deprivation therapy for Asian patients with advanced prostate cancer.

Purpose: The study aimed at investigating prostate cancer patients' choice of androgen deprivation treatment (ADT) and possible factors that would affect their preferences of ADT.

Methods: This was a single-centre cross-sectional study investigating the usage and preferences of ADT. Consecutives prostate cancer patients who were receiving injectable luteinizing hormone-releasing hormone (LHRH) agonist or antagonist were recruited from the prostate cancer clinic in a tertiary academic hospital. Patients who received bilateral orchidectomy or those who could not consent to the study were excluded. Disease characteristics, treatment information and patient background were documented. The survey collected information related to their change in ADT regimen, preferences on drug usage (routes and frequency of administration) and their reasons. A hypothetical set of three drug formularies was designed. Questions regarding patient preference and the contributing reasons raised in the format of questionnaire.

Results: 100 patients completed the survey. Most patients started with more frequent injections (3-monthly, 54%; 1-monthly, 38%) and switched to 6-monthly injections (89%) at the time of the survey. Primary reasons for the change were healthcare opinion (72%) and less frequent treatment (51%). Three options of ADT (oral daily, 1-monthly and 6-monthly injection) with the same efficacies and side effect profile were offered: 61% preferred 6-monthly injection, 1% preferred 1-monthly injection and 38% preferred oral regimen. When patients were informed of lower cardiovascular side effects in 1-monthly injection or daily oral drug, patients' preference was 56% (6-monthly), 6% (1-monthly), and 39% (oral). Patients with polypharmacy (more than 5 regular medications) were more inclined to choose injections (p = 0.025). Patient age, educational background, employment status, marriage status and disease status were not found to be statistically significant contributing factors to patient preference.

Conclusion: 6-monthly ADT injection was the preferred ADT despite greater cardiovascular risks. Among 1-monthly or daily oral LHRH antagonist, more patients prefer oral option. Convenience factor was highly valued.