Abstract 663P
Background
Osteosarcopenia is (i) an age-related, progressive loss of musculoskeletal structure and functionality, contributing to falls, fractures, and premature death, and (ii) amongst the detrimental consequences of having cancer and undergoing cancer therapy. While the complex interactions between bone and muscle health are being explored, efforts to diagnose and prevent osteosarcopenia in prostate cancer patients (pts) focus almost exclusively on bone health management. Ra223 is known to contribute to osteopenia, but there is a lack of studies on the impact of Ra223 on sarcopenia.
Methods
We identified 52 men with mCRPC that had received ≥2 cycles of Ra223 between Feb 2015 and Dec 2019 at Odette Cancer Centre (Toronto, ON, Canada), and who had at least a baseline abdominopelvic CT scan (ie at the beginning of Ra223 therapy) and ≥1 follow-up CT scan. Using the contour tool of the eUnity imaging platform (Client Outlook Inc, Waterloo, ON, Canada), two independent assessors obtained the total contour area (TCA) and averaged Hounsfield units (HU) of the left and right psoas muscles at the level of the inferior endplate L3. We also calculated the Psoas Muscle Index (PMI) by dividing the TCA by the square of pts’ height in meters. Mixed-effects analysis was performed regarding the TCA, HU, and PMI measurements and according intra-patient changes across the following CT time points: ≤2 years before Ra223, baseline, and 6 and/or 12 months following start of Ra223.
Results
The TCA values measured by each assessor were highly correlated (r between 0.8991 and 0.9125 across the various time points). While there was a gradual psoas TCA and PMI decline over the entire study period analyzed (p=0.0020 for TCA, p=0.0028 for PMI), Ra223 therapy did not accelerate sarcopenia development. Similarly, Ra223 did not aggravate the gradual decline of psoas density (p<0.0001 for HU) seen over time.
Conclusions
Ra223 does not appear to accelerate sarcopenia. Thus, the worsening of sarcopenia in men undergoing Ra223 is rather attributable to concurrent androgen deprivation therapy, amongst others.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Joseph and Silvana Cancer Research Fund, Toronto, ON, Canada.
Disclosure
U. Emmenegger: Honoraria (self), Honoraria (institution), Advisory/Consultancy, Research grant/Funding (self), Research grant/Funding (institution): Bayer Inc Canada. All other authors have declared no conflicts of interest.