BACKGROUND

Treatments for cancer cachexia, defined as involuntary weight and muscle mass loss leading to significant functional impairment, remain unavailable partly due to insufficient improvement of clinically meaningful outcomes in current trials. By reflecting downstream effects of cellular function, metabolomics may identify mechanisms contributing to poor functional performance.

Previous metabolomic studies in cancer cachexia have identified alterations in amino acid metabolism with weight loss or low muscularity; none have examined perturbations with poor physical function. We hypothesized that distinct metabolic signals in plasma and muscle are associated with weight loss, low muscle mass, and impaired function in cancer cachexia.

METHODS

We enrolled patients planning elective laparotomy for gastrointestinal or genitourinary cancer.

Handgrip strength (HGS), stair climb power (SCP), and fasting plasma were collected within 2 weeks prior to surgery; rectus abdominis samples were obtained during surgery. Metabolomic perturbations associated with physical function (HGS, SCP), muscularity (lumbar cross-sectional area ‘CSA’ from opportunistic CT), or weight loss (> 5% over previous 6 months) were examined in plasma and muscle.

The Mann-Whitney U-test compared metabolite abundance between weight-losing and weight-stable patients, while Spearman’s correlation tested associations of abundance with CSA, HGS, or SCP. The ‘Globaltest’ method assessed pathway alterations with weight loss, CSA, HGS, or SCP; the Benjamini-Hochberg adjustment was used to control for false discovery.

RESULTS

Patients (N = 72) were male, median age 65 [interquartile range: 59-70], with 57% genitourinary cancer.

Plasma and skeletal muscle metabolomic data were collected (N = 64 and N = 68, respectively). Weight loss was associated with significantly altered microbial, amino acid/derivative, fatty acid/lipid, and caffeine-related metabolism pathways in plasma (adjusted p < 0.1).

Lower CSA was associated with significantly altered fatty acid/lipid, galactose, glycerophospholipid, and histidine metabolism and bile secretion pathways in skeletal muscle (adjusted p < 0.1). Worse HGS was nominally associated with altered plasma branched chain amino acid biosynthesis and altered skeletal muscle glutathione metabolism (unadjusted p ≤ 0.05), while worse SCP was nominally associated with altered skeletal muscle amino sugar/nucleotide sugar metabolism and phenylalanine, tyrosine, and tryptophan biosynthesis (unadjusted p ≤ 0.05).

CONCLUSIONS

Significant metabolomic alterations in plasma and skeletal muscle characterized cancer-related weight loss and reduced CSA, respectively.

Nominal, function-specific alterations were detected with worse HGS and SCP, which were distinct from those associated with weight loss or low CSA. Future larger studies may further characterize metabolomic profiles related to various functional outcomes and guide development of therapeutic targets to improve functional performance.