Assessment of Patient and Clinician Perspectives on Clinically Meaningful Extension of Progression-free Survival in Prostate Cancer

Background and objective: It is widely accepted that the value of treatments for incurable metastatic cancer depends on their ability to improve overall survival (OS), quality of life (QoL), or both. Progression-free survival (PFS) is frequently used as a primary endpoint because of challenges in accurately assessing OS and QoL. The perceived value of extending PFS when there is uncertainty regarding the benefit to OS/QoL may vary between clinicians and patients. The aim of our study was to measure patient and clinician perspectives on what defines a clinically meaningful PFS benefit.

Methods: We conducted an observational study using a self-administered questionnaire. Participants included patients with advanced prostate cancer (PC) and medical oncology clinicians treating patients with PC. The questionnaire presented a hypothetical scenario of metastatic castrate-resistant PC (mCRPC). Participants were asked about their willingness to undergo or prescribe treatment offering PFS benefits despite uncertain OS outcomes. Participants specified the minimum extension of PFS (ePFS_min) beyond the estimated 18-mo duration outlined in the scenario while considering varying toxicity levels.

Key findings and limitations: Between April and May 2024, 54 patient responses and 27 clinician responses were received. Some 50/54 patient participants (92.6%) and 22/27 clinician participants (81.5%) expressed willingness to accept a prospective treatment associated with longer PFS but uncertain OS benefit. For treatment with no or mild toxicity, the median ePFS_min for treatment acceptance was >12 mo for patient participants and 3-6 mo for clinician participants. For treatment with severe toxicity, 40.7% of patients and 51.9% of clinicians would not accept treatment; the ePFS_min for treatment acceptance was 3-6 mo for patient participants and >12 mo for clinician participants.

Conclusions and clinical implications: Most patients and clinicians are open to mCRPC treatment with evidence of PFS benefits despite OS uncertainty. Patients needed longer PFS extension to justify treatment but were more accepting of side effects and placed greater importance on a prostate-specific antigen or radiological response than clinicians. The relationship between ePFS_min and treatment acceptance according to toxicity levels for patients was unclear, limited by the nature of the self-administered questionnaires.

Patient summary: We surveyed patients and doctors about their views on an imaginary treatment for advanced prostate cancer that could delay disease progression but with no certainty about whether it would extend life expectancy. Both patients and doctors were open to this treatment, but patients expected a longer delay in disease progression than doctors before being willing to accept this imaginary treatment. Many patients and doctors would also not consider the treatment if it caused severe side effects.