Exploring the association between pro-inflammatory mediators and sarcopenia in cancer patients through different diagnostic tools: a narrative review.

Background and objective: Sarcopenia, characterized by the progressive loss of skeletal muscle mass (MM) and muscle function, is a common and debilitating condition in cancer patients, significantly impacting their quality of life, treatment outcomes, and overall survival. The pathophysiology of sarcopenia is multifactorial, involving metabolic, hormonal, and inflammatory changes. Recent research highlights the role of chronic inflammation in the development and progression of sarcopenia, with pro-inflammatory cytokines being key mediators of muscle catabolism. The primary objective of this study was to assess the role of pro-inflammatory cytokines in identifying sarcopenia among cancer patients. As a secondary objective, we aim to investigate whether the methods used for assessing sarcopenia, both imaging and functional, align with established guidelines.

Methods: A search of the Web of Science was conducted for English-language articles published since 2005, with the following terms: "Cancer" AND "Sarcopenia" AND "Pro-inflammatory cytokine*" OR "Interleukin*". Inclusion criteria included peer-reviewed controlled trials, observational studies, case reports, and case series. To avoid redundancy, articles with results which were included in systematic reviews, narrative reviews, or scoping reviews were excluded from this review.

Key content and findings: The analysis of 10 selected papers, including 1,138 cancer patients, revealed a lack of assessment of muscle strength (MS) and muscle functional performance in most of the studies on sarcopenia, contradicting the comprehensive nature of sarcopenia that includes MM, MS, and muscle functionality. There is no standardization of pro-inflammatory mediators for sarcopenia identification.

Conclusions: Future research should focus on establishing cutoff points for inflammatory mediators and identifying which cytokines are linked to sarcopenia. Given the complexity of sarcopenia in different cancers, new projects should investigate whether cytokine expression depends on the tumor type. Moreover, considering that the majority of the study population comprised elderly individuals with primary sarcopenia, it is crucial to discern the extent to which the findings are influenced by age versus cancer-related factors.