Barriers and Facilitators of Treatment Intensification in Metastatic Castration-Sensitive Prostate Cancer.

Importance: Despite evidence of clinical benefits and guidelines recommending first-line treatment intensification (TI) for metastatic castration-sensitive prostate cancer (mCSPC), the majority of patients do not receive it. Objective: To identify barriers to and facilitators of first-line TI. Design, Setting, and Participants: The IMPLEMENT study (December 2022 to August 2024) comprised 3 phases and used a mixed-methods, qualitative and quantitative approach. US-based urologists and oncologists who were primary treaters for 1 or more patients with mCSPC in the past 6 months, had been practicing for 2 to 35 years, spent 50% or more of their time in direct patient care, and were able to provide informed consent were included. Exposure: Phase 1 consisted of semistructured interviews based on the Theoretical Domains Framework. Phase 2 consisted of a discrete choice experiment to identify priority barriers and helpful resources. Phase 3 consisted of cocreation sessions to ideate potential solutions to underutilization based on the findings of the previous phases. Main Outcomes and Measures: The primary outcome in phase 1 was barriers to and facilitators of first-line TI, as identified through thematic analysis. The primary outcome of phase 2 was perceived helpfulness of potential resources for first-line TI decisions, measured with a coefficient of helpfulness [CoH] for each resource. The primary outcome of phase 3 was potential solutions to increase TI uptake, as cocreated and ranked by urologists and oncologists. Results: In total, 352 participants were included in IMPLEMENT, with 36 in phase 1 (33 men [92%]; mean [range] years in practice, 19 [5-34]), 302 in phase 2 (253 men [84%]; mean [range] years in practice, 18 [4-35]), and 14 in phase 3 (12 men [86%]; mean [range], years in practice, 20 [8-35]). In each phase, one-half of participants were oncologists and one-half were urologists (18 urologists and 18 oncologists in phase 1, 151 urologists and 151 oncologists in phase 2, and 7 urologists and 7 oncologists in phase 3). In phase 1, 5 domains had the greatest perceived influence on intensification: memory, attention, and decision processes; environmental context and resources; knowledge; beliefs about consequences; and social or professional role. Urologists more commonly reported barriers to intensification, while oncologists more commonly reported facilitators. In phase 2, urologists found decision-support tools most helpful (CoH, 3.27; 95% CI, 2.90-3.65), while oncologists preferred databases of posttreatment options (CoH, 2.58; 95% CI, 2.29-2.89) and clinical trial summaries (CoH, 2.41; 95% CI, 2.14-2.69). In phase 3, cross-specialty tumor boards were ranked by both specialties as the best solution to address TI underutilization. Conclusions and Relevance: This study using a mixed-methods approach with quantitative and qualitative components found that the issues underlying TI underutilization were numerous and multifactorial; the barriers encountered by physicians and the resources to help address them varied by specialty. These findings offer insights into physician-supported strategies that could help improve rates of first-line TI for mCSPC in the US.