ASCO GU 2019: Cost-Effectiveness of Metastasis-Directed Therapy in the Setting of Oligometastatic Hormone-Sensitive Prostate Cancer

San Francisco, CA ( Dr. Parikh discussed that previously published data have suggested there may be a benefit for metastasis-directed therapy in patients with oligorecurrent hormone-sensitive prostate cancer. 

The group aimed to determine the cost-effectiveness of metastasis-directed therapy (MDT) vs. systemic treatment upfront by constructing a Markov model to compare three treatment strategies: 

  1. MDT followed by salvage Abiraterone + androgen deprivation therapy (ADT)
  2. Abiraterone + ADT upfront
  3. ADT alone upfront
To inform model assumptions, the study utilized data from several studies including STOMP, STAMPEDE, and the STAMPEDE M1 sub-analysis (recently presented at ESMO 2018).  Costs were obtained from Medicare, with utilities derived from the literature.  MDT was assumed to be stereotactic body radiotherapy (SBRT) over three fractions.  Upon failure of initial systemic therapy, patients were assumed to receive “life-prolonging” drugs as per patterns in STAMPEDE.  Total time horizon of the study was 10 years, with a willingness-to-pay (WTP) threshold of $100,000 per quality-adjusted life year (QALY). 

At 5 years, ~ 14% of patients who received MDT upfront had not yet started systemic therapy, with ~50% still with metastatic hormone-sensitive disease. At 10 years, strategy #1 (MDT followed by salvage Abiraterone + ADT) appeared to be the most cost-effective, with an ICER of $92K/QALY when compared to strategy #3.  Strategy #2, although with marginally higher effectiveness, also had a significantly higher cost compared to strategy #1, translating to ICER of $1.4M/QALY.  Price of Abiraterone was found to be a sensitive model input, with a ~88% drop in Medicare pricing necessary to make strategy #2 (Abiraterone + ADT upfront) the most cost-effective strategy.

In summary, Dr. Parikh stated that MDT may serve as a treatment with tremendous value in the oligo-recurrent metastatic setting. The potential ability to defer systemic treatments may be especially beneficial in certain patients. However, future quality research is needed to answer the remaining questions:

  1. Does MDT cause a meaningful delay in the natural history of prostate cancer?
  2. Is there any benefit to combining MDT with upfront advanced hormonal therapy in the oligorecurrent setting? 
Many more questions exist in this space which will hopefully be uncovered in the future. 

Presented by: Neil Rohit Parikh, MD, MBA, Department of Radiation Oncology, University of California – Los Angeles, Los Angeles, CA

Written by: David B. Cahn, DO, MBS, @dbcahn, Fox Chase Cancer Center at the 2019 American Society of Clinical Oncology Genitourinary Cancers Symposium, (ASCO GU) #GU19, February 14-16, 2019 - San Francisco, CA
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