There are multiple etiologic factors that can result in sarcopenia, including physical inactivity, malnutrition, neuro-hormonal alterations, and the inflammatory milieu. In patients with certain cancers, recent work suggests that cancer-associated inflammation plays a significant and additive role, accelerating muscle atrophy, and resulting in declines in strength, which are associated with poor clinical outcomes.
Cancer-associated sarcopenia has increasingly been examined as a predictor of mortality, complications, and treatment-related toxicity. In particular, the association of sarcopenia with worse survival and treatment complications has been consistently demonstrated in patients with renal cell carcinoma (RCC). Of note, RCCs commonly present with heightened expression of pro-inflammatory pathways which have been demonstrated to be associated with poor prognosis. In this review, we synthesize the available literature to date detailing the association between radiographic sarcopenia and outcomes across the spectrum with an emphasis on associations with inflammation.
First, we provide critical background information for understanding sarcopenia, its assessment, and its application in clinical outcomes research. The pathophysiology of sarcopenia and the pro-inflammatory state that occurs in RCC and contributes to muscle atrophy is described. We detail the radiographic characterization of muscle mass and quality from routine cross-sectional imaging with a focus on computed tomography and magnetic resonance imaging given their ubiquitous role in the staging and post-treatment surveillance of RCC. Following this background information, we present a summary of the body of work evaluating the prognostic value of sarcopenia and surrogates for inflammation across the spectrum of RCC and review recent data detailing the dynamic changes in muscle mass observed with contemporary systemic therapies. Finally, we present some thoughts on future directions for sarcopenia research in RCC, with an emphasis on muscle analysis techniques and reporting standardization, analyzing muscle quality in addition to quantity, and present some pathways toward adopting body composition assessments into routine clinical practice.
The data is consistent in that measurement of muscle mass and quality sarcopenia provides important predictive information for patients with RCC that can inform shared clinical decision-making and patient counseling. This review can help urologists and other clinicians interpret emerging sarcopenia research and understand its utility as the field moves closer toward clinical application.
Written by: Benjamin N. Schmeusser, MD, MS1 Viraj A. Master, MD, PhD1,2 Sarah P. Psutka, MD, MS3,4
- Department of Urology, Emory University School of Medicine, Atlanta, GA, USA
- Winship Cancer Institute, Emory University, Atlanta, GA, USA
- Department of Urology, University of Washington, Seattle, WA, USA
- Fred Hutchinson Cancer Center, University of Washington, Seattle, WA, USA