Introduction: Hormonal therapy is the standard of care in prostate cancer treatment. The approval of the first oral androgen deprivation therapy, relugolix, to treat prostate cancer patients provides an opportunity to review adherence to oral and injectable/implantable hormonal therapies to aid patients and physicians in making informed decisions.
Methods: A PubMed search for available literature on adherence to hormonal therapy in prostate cancer was conducted, including published data on relugolix.
Results: Adherence to oral antiandrogen therapy was above 90% by medication possession ratio in several studies worldwide and from 75% to 91% by proportion of days covered. For injectable/implantable androgen deprivation therapy, adherence to treatment ranged from 71% to 95%. In general, 60% and 29% of injections were reported to be delayed by more than 1 week and 2 weeks, respectively, with some patients experiencing testosterone increases (tests above 50 ng/dL). Although real-world data on adherence to relugolix are currently unavailable, pharmacokinetic/pharmacodynamics models demonstrated that, if necessary, treatment interruption up to 7 days would still maintain testosterone suppression levels.
Conclusions: In general, adherence to hormonal therapy is high in prostate cancer. Studies revealed that adherence to injectable androgen deprivation therapy dosing schedules is important to maintain castrate levels. Pharmacokinetic/pharmacodynamics models showed that relugolix treatment interruption up to 7 days had minimal impact on testosterone suppression levels.
Keywords: administration and dosage; gonadotropin-releasing hormone; medication adherence; prostatic neoplasms; relugolix.