In this study, the authors aimed to determine the scope and impact of late administrations of ADT in prostate cancer patients. The authors evaluated the timeliness of LHRH agonist administration, subsequent rate of testosterone breakthrough above 50 ng/dl, and frequency of testosterone and PSA testing prior to dosing. Administrations and testosterone tests were defined as “late” if the drug was not administered after day 33, 98, 129, or 195 for 1-, 3-, 4-, and 6-month formulations, respectively, as seen in Figure 1.
Figure 1: Methodology
A total of 26.9% of LHRH agonist administrations were late: 14.4% were <=1 week late, 3.1% were between 1-2 weeks late, and 9.4% were >2 weeks late. The percent of late administrations was high across all formulations: 53%, 19%, 26%, 25% for 1-, 3-,4- and 6-month formulations, respectively (Figure 2).
Figure 2 – Proportions of late administrations:
A total of 28% of testosterone values exceeded 50 ng/dl when administrations were late. In contrast, only 4% of testosterone values exceeded this level when doses were administered early or on time (Figure 3). Patient demographics are shown in Table 1.
In conclusion, across LHRH agonists, greater than a quarter of administrations were late. Among late administrations, about half were >1 week late, and more than a third were >2 weeks late. Late administrations were correlated with ineffective castration over 19% of the time when comparing across all formulations. For injections, testosterone levels were not monitored as frequently as PSA levels. Therefore, considering the presumed clinical benefits of maintaining effective testosterone suppression through the course of ADT, clinicians should administer treatments within the approved dosing instructions, routinely monitor testosterone levels, and consider prescribing treatments with the appropriate dosing interval to maintain testosterone at castrate levels at all times.
Figure 3 – Proportion of T tests with levels above 50 ng/dl by the timeliness of administrations – by formulations:
Table 1 – Patient demographics:
Presented by: Rumiko Sugimura, Yokohama City University Medical Center, Department of Urology and Renal Transplantation, Yokohama, Japan
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre, @GoldbergHanan at the 34th European Association of Urology (EAU 2019) #EAU19, conference in Barcelona, Spain from March 15-19, 2019.