Though low muscle mass is common in patients with advanced cancer and known to be associated with worse mortality, less is known about the relationships between muscle quality and cancer outcomes.
Now a new study, in addition to again showing that poorer muscle mass (a measure of muscle quantity) was linked to worse survival, found that poorer muscle radiodensity (a measure of muscle quality) was also linked to worse survival, health care use, and symptom burden in a group of patients with advanced cancer. The data was published online ahead of print in the Journal of the National Comprehensive Cancer Network earlier this year (2021; https://doi.org/10.6004/jnccn.2020.7618).
For the study, researchers analyzed CT scans of 677 patients with advanced cancer who had an unplanned hospitalization between September 2014 and May 2016 to measure muscle mass and radiodensity. Patients' physical and psychological symptoms were assessed during their hospital stays. And the researchers examined re-admission data for 90 days after the patients were hospitalized for their initial hospital stay to measure health care utilization. Mortality data was also analyzed.
Beyond the findings that poor muscle radiodensity was linked to worse outcomes and higher symptom burden, the data also revealed that patients who were female and those who were older were more likely to have lower muscle mass and radiodensity. People with higher BMI tended to have higher muscle mass, but lower muscle quantity.
Research in larger, more diverse populations with longer follow-up will be needed, as well as studies designed to better understand the direction of these relationships. But this study is an important step in recognizing muscle quality, in addition to quantity, as a predictor of (and possibly a modifiable factor when it comes to) cancer outcomes, noted the study's lead researcher, Ryan D. Nipp, MD, MPH, a gastrointestinal oncologist and health services researcher at Massachusetts General Hospital Cancer Center.
"We hope that by improving our understanding of these relationships, this study will inform future intervention development," Nipp shared with Oncology Times. "Our findings could inform future work seeking to investigate potential mechanisms for how low muscle mass and radiodensity impact patient outcomes, identify patients at-risk for experiencing changes in muscle mass or radiodensity, and develop interventions addressing adverse muscle changes in oncology."
Why considering muscle quality could lead to interventions that improve quality of life and survivorship care
This data is significant because much of the literature on body composition and cancer outcomes has focused on muscle quantity, said Grant Williams, MD, Assistant Professor in the Division of Medicine - Hematology and Oncology and Director of the Cancer & Aging Program at the O'Neal Comprehensive Cancer Center at The University of Alabama at Birmingham. "Only in the last few years has muscle radio density, a surrogate measure of muscle quality as known as myosteatosis, been examined," noted Williams, who was not involved in the research. "The results of the association of symptom burden and health care use with muscle quality are new and important."
The work suggests that both muscle mass and quality may help inform the risk/benefit analysis in treatment decisions. And, importantly, muscle mass and muscle quality are not necessarily fixed factors.
"These measures are amendable to intervention and can be improved with nutrition and exercise interventions. How these interventions impact cancer outcomes is an area of ongoing focus," Williams said.
This research and further studies that address this question could inform what those interventions look like, according to Scott J. Capozza, PT, MSPT, Board Certified Clinical Specialist in Oncologic Physical Therapy at Smilow Cancer Hospital and Yale Cancer Center. "Increasing the quality of one's weight through muscle development could be more important than simply trying to regain body weight to address cancer-related sarcopenia," he said in a statement.
"Skilled clinicians, such as oncology certified dietitians and physiotherapists, are able to develop evidence-based interventions to safely increase the quality of muscle mass," noted Capozza, who was not involved in this study. "I look forward to future studies where these clinicians can be incorporated to address the quality of life and overall survival of patients with advanced cancers through nutrition, exercise, and physical rehabilitation."
Current data limitations include population size and limited sociodemographic diversity
It's important to note that this study was conducted at a single, large academic cancer site in a population with limited sociodemographic diversity, Nipp said. Participants were primarily White (92%), married (67%), and educated beyond high school (59%). About half (51%) of the patients were women. And the most common cancer types were gastrointestinal (37%), lung (17%), and genitourinary (9%).
"Our findings may not generalize to more heterogenous populations," Nipp said.
Another limitation is that skeletal muscle was analyzed at a single time point. So there's a lack of data about the longitudinal changes in patients' muscle health, he explained.
Nipp and his colleagues in future work hope to build upon these findings to develop and test ways to better detect individuals at greatest risk for experiencing adverse muscle changes who might benefit from targeted supportive care interventions.
Sarah DiGiulio is a contributing writer.