To discuss the recent discoveries and limitations of the available literature on emerging circulating biomarkers of cancer cachexia.

Studies on circulating factors in cancer cachexia show promising alternatives for diagnosing the syndrome in a minimally invasive manner in the clinic setting, as well as potential targets for cancer cachexia treatment. Factors secreted by the tumor and the adipose tissue, such as extracellular vesicles and soluble proteins, respectively, have been shown to either directly induce wasting in vitro and in vivo or to be altered in the cachectic phenotype. The detection and characterization of circulating cells allows detection of the precachectic stage and the levels of the soluble immune checkpoint protein programmed death ligand-1 (PD-L1) are correlated with the presence of the hallmarks of cancer cachexia.

Structural, molecular, and metabolic alterations have been observed in various tissues, revealing the occurrence of sustained inter-compartment crosstalk in cachectic patients. Early diagnosis of cancer cachexia becomes crucial to avoid the establishment of refractory cachexia through the implementation of interventions that may attenuate systemic inflammation and muscle loss. More studies on human cancer cachexia are required in order to address the recently discovered cachexia-associated circulating factors’ value as biomarkers of the syndrome.