In a small, but elegantly executed study, researchers in Taiwan used CT imaging to measure changes in the skeletal muscle mass, subcutaneous fat, and visceral fat for 125 prostate cancer patients at baseline and then six months after they started androgen deprivation therapy. The researchers also collected data on the men’s weight and BMI. Furthermore, they followed the men for a median of 49 months. During that time,16 died of causes other than cancer and 17 died of prostate cancer.
Of all the variables measured, it was loss of skeletal muscle mass, as indicated by the skeletal muscle index (SMI), that was a predictor of non-cancer mortality. Specifically, the authors reported that "each 1% decrease in SMI was independently associated with a 9% increase in the risk of a non-cancer mortality.” Patients who had a SMI loss >5% (which was almost half of the men) had a 5.6 fold increase of dying from something other than prostate cancer compared to the men who maintained their SMI. Importantly, this was independent of any changes in the men's weight, BMI, subcutaneous, or visceral fat. It wasn't those other variables that were the "killer"; it was a loss of muscle mass.
Losing muscle mass can lead to increased risks or falls and fractures, including serious ones like a broken hip, which carries a high risk of early death. Loss of muscle mass may also affect visceral functions, like coughing, since the muscles of the body wall are used to forcefully expel material from the body, including air from the lungs. Having a forceful cough can help fight off pneumonia and, in that regard, it is noteworthy that the most common cause of non-cancer death in the study was pneumonia.
Us patients are typically well aware of the change in our weight and the increase in body fat that comes with ADT. We may be less aware of loss of skeletal muscle. We might be able to control our weight by dieting, but this does not help us preserve muscle mass. Maintaining skeletal muscle requires using those muscles!
The sample size in this study is relatively small and we hope that the study will be duplicated with a larger sample. But, if these results hold up in future studies, they confirm the importance of regular, intense, physical exercise for maintaining one’s overall health while on ADT.
Cancer centres are increasingly offering free exercise programs and resources for patients. It may be worthwhile to inquire about options at your local cancer centre. You can also check our website for links to a couple of web-based resources (http://www.lifeonadt.com/links).
To read the full article, see: https://pubmed.ncbi.nlm.nih.gov/34604058/
Reference:
Chiang PK, Tsai WK, Chiu AW, Lin JB, Yang FY, Lee J. Muscle Loss During Androgen Deprivation Therapy Is Associated With Higher Risk of Non-Cancer Mortality in High-Risk Prostate Cancer. Front Oncol. 2021 Sep 17;11:722652. doi: 10.3389/fonc.2021.722652. PMID: 34604058; PMCID: PMC8485032.