Muscle mass, density may be linked to cancer outcomes
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Muscle mass appeared significantly associated with survival outcomes among patients with advanced cancer undergoing an unscheduled hospitalization, according to a study published in Journal of the National Comprehensive Cancer Network.
Moreover, researchers found associations of muscle radiodensity, or quality of muscle, with symptom burden and other patient-reported outcomes.
“We are seeing more and more the importance of patient-reported outcomes in the literature and in clinic,” Ryan D. Nipp, MD, MPH, gastrointestinal oncologist and health services researcher at Massachusetts General Hospital Cancer Center and Harvard Medical School, as well as a HemOnc Today NextGen Innovator, said in an interview with Healio. “We also are increasingly seeing research supporting the importance of body composition, such as muscle mass and muscle wasting, in the literature. These topics of patient-reported outcomes and body composition analysis align well with my passion to optimize care delivery and outcomes for patients with cancer. Thus, this prompted us to investigate the relationships between these emerging topics.”
Nipp and colleagues at Massachusetts General Hospital evaluated 677 patients (mean age, 62.86 ± 12.95 years) with advanced cancer who were hospitalized unexpectedly between September 2014 and May 2016. They evaluated muscle mass and radiodensity using CT scans performed as part of routine clinical care within 45 days prior to study enrollment and compared the results against clinical and patient-reported outcomes.
The researchers reported a significant correlation of higher muscle mass with improved survival (HR = 0.97; P < .001). In addition, higher muscle radiodensity appeared significantly associated with lower symptom burden as measured by the Edmonton Symptom Assessment System (ESAS) for physical symptoms (B, 0.17; P = .016) and total symptoms (B, 0.29; P = .002) and PHQ-4 for depression (B, 0.03; P = .006) and anxiety (B, 0.03; P = .008). Higher muscle radiodensity also appeared associated with shorter hospital length of stay (B, 0.07; P =.005) reduced risk for readmission or death in 90 days (OR = 0.97. P < .001) and improved survival (HR = 0.97; P = .001).
Nipp spoke with Healio about the findings, including interesting correlations of BMI with muscle mass and radiodensity, and how this work eventually might be applied to clinical practice.
Healio: What inspired you to conduct this study?
Nipp: A few years ago, in a secondary analysis of a randomized trial, we looked at muscle mass correlating with patient-reported quality of life and mood symptoms. I had always been on the lookout for how we could build on this literature and further demonstrate the relationships among patient-reported outcomes and body composition analysis. In addition, hospitalized patients with advanced cancer represent a population at increased risk for high symptom burden and changes in body composition.
Healio: How did you determine muscle mass and muscle radiodensity?
Nipp: We used CT scans and worked with our radiology team at Massachusetts General Hospital, which has developed strategies to help quantify and further assess a patient’s muscle mass and radiodensity. One of the more established ways is to look at the L3 vertebral level, where we commonly measure a patient’s muscle health. So, we had to limit our cohort to patients who had a CT scan within the given time frame. Additionally, we had previously enrolled a cohort of patients who were hospitalized at Massachusetts General Hospital and asked them about their symptom burden. Ultimately, using our prior sample and limiting to those with evaluable CT scans, that allowed us to have 677 patients who had scans at the proper level where able to quantify their muscle mass and radiodensity.
Healio: What did you find?
Nipp: We found that both muscle radiodensity and muscle mass correlated with survival, as we would have expected from the literature. We went further and looked at patient-reported outcomes, which included symptoms assessed with the ESAS, as well as the PHQ-4 for psychological symptoms. That enabled us to assess whether the patient’s muscle mass and radiodensity correlated with their symptoms, and we found that only radiodensity demonstrated significant associations with patients’ symptom burdens. We also looked at health care utilization, which included hospital length of stay and readmission. We found a signal for radiodensity correlating with health care utilization outcomes, whereas muscle mass did not. More work is needed to confirm what we found and continue to build upon the idea that muscle radiodensity, or muscle quality, seems to be a sensitive predictor of patient outcomes and may be useful for picking up on differences in clinical outcomes.
Healio: Your study showed associations of higher BMI with higher muscle mass but lower muscle radiodensity. What do you think this means?
Nipp: The finding for BMI intrigued us. We’re speculating, but the thought is that more muscle mass could cause a person’s BMI to increase, whereas radiodensity may be a marker of muscle quality, as a measure of greater intramuscular adipose tissue. Therefore, a higher BMI may contribute to fatty infiltration of muscle tissue, and thereby lower radiodensity. To put it in another way, people with lower body weight could still have high muscle density. Future investigations are needed to study whether muscle radiodensity is truly a muscle quality indicator.
Healio: Could muscle radiodensity become a new predictor of outcomes among patients with cancer?
Nipp: I think with more work, we’re headed toward this in the future. Data about body composition, as captured on routine CT scans, could be another piece of information that factors into our discussions with patients about how they’re doing. Perhaps we could go further and say, “We’ve noticed these muscle changes on your CT scan and, based on this, all arrows point toward this outcome, and now we need to intervene and make these changes.” It will be important for future work to investigate if exercise and nutrition interventions could change the trajectory of poor muscle health and impact both patient-reported and clinical outcomes.
Healio: What are the next steps for research?
Nipp: For this dataset, our research team will look at other ways of evaluating body composition. We’ve looked at muscle mass and radiodensity with the current work, yet we could also characterize patients’ adipose tissues. We also can investigate muscle and adipose at various other vertebral levels. Some investigators also have been looking at the intersection of muscle mass and density, and there’s an idea called muscle gauge, which takes both into account. I am excited for the future research that will be motivated by our current findings, and I hope to see ongoing efforts to better understand and address muscle health in oncology.
For more information:
Ryan D. Nipp, MD, MPH, can be reached at Massachusetts General Hospital, 55 Fruit St., Boston, MA 02114; email: rnipp@mgh.harvard.edu.
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