Losses in muscle mass and strength are commonly associated with the aging process. Starting around the third and fourth decade of life we start to see a decrease in both muscle mass and muscle strength that increases linearly with increasing age. This is due to a multitude of factors – either genetic, existence of comorbid conditions, lifestyle and environmental factors – but particularly when you look at older adults with cancer this becomes a more multifactorial cause of a lot of these losses. These patients are not only at risk for age-related losses in sarcopenia but also have cancer and cancer treatment related causes of having losses in sarcopenia.
So what our real interest and objective in this study was to look at older adults with cancer, that develop cancer, and look at changes in sarcopenia measures in the pre-diagnosis and post-diagnosis windows compared to a control population of older adults. The Health ABC study is actually a large community dwelling study of over 3,000 patients from the United States that were followed annually to have a better understanding of body composition and its outcomes in older adults.
Within these 3,000 patients that were followed annually for six years about 500 patients actually developed incident cases of cancer. In those patients that actually were diagnosed with cancer they went back and found the type of cancer, got their pathology report and were able to confirm their cancer diagnosis. So what we really did is looked at three different sarcopenia indices, including lean body mass that was assessed by DEXA, hand grip strength using a hand-held dynamometer and gait speed that was done annually. We were able to look at changes in these indices before the cancer diagnosis as well as after the diagnosis and comparing that to a normal aging population.
So what we actually found is in the pre-cancer diagnosis window we actually did see decreases in the slope or the loss of gait speed but we didn’t find any changes in lean body mass or hand grip strength. After the cancer diagnosis we saw a more steep decline in lean body mass and no difference in the slope of change in hand grip strength or gait speed compared to a control population. These losses or changes were actually more dramatic for prostate and lung cancer as compared to other cancers.
Some of this really provides some of the first evidence, particularly compared to a control population, that cancer and its treatment actually can accelerate some of these losses we see in these measures of sarcopenia. Further research needs to be done to look at how these changes actually impact outcomes beyond just survival and chemotherapy toxicity but functional decline, health related quality of life, falls, other things that we know are important to our older patients. Once we are able to better understand how it’s linked to those outcomes and what are the causes of some of these losses in sarcopenia measures we really need to move forward with more interventional studies to see how we can improve these outcomes.
Were there any controlling factors assessing for comorbidities?
We made sure these patients didn’t have a history of cancer but, no, we didn’t control for other comorbid factors. We really looked at age at the time that they were enrolled in the study, gender, race, ethnicity and the site in which they were enrolled but otherwise we didn’t look at other comorbid factors.
Is there any reason why the lung and prostate patients fared worse?
It’s hard to know. One of the limitations of this study is we didn’t have a lot of treatment, or really any cancer treatment, related information. Prostate cancers, particularly in the post-diagnosis window get a lot of androgen deprivation therapy which is well known to cause losses in muscle mass and strength. That could be part of it. Lung cancer in itself is often diagnosed at later stages of disease, typically in the more stage 3 and stage 4, and can have a more inflammatory effect which could also explain some of these. Each cancer type is going to be unique and different and unfortunately we didn’t have large samples of others like pancreatic cancer and some of these others that were less common within our population. It does beg a question as really honing in on those factors that really accelerate sarcopenia more than others so that we can better tailor these interventions to those populations.
What would you like to see in the follow up?
Some of my next steps actually have a grant, a K08 grant from the NCI in the United States, looking specifically at older adults with colorectal cancer, looking and doing pre testing at the time of diagnosis and following these patients after their treatment up to six months looking at all these things using CT scans so we can understand their body composition, gait speed, strength and what changes, what actually causes some of these changes to occur so that we can really hone in on a granular level and understand what risk factors there are for this. But, yes, registries, anything that has a lot more of that granular data so we can understand the risk factors and causes for some of these accelerated losses in sarcopenia.