Background: Despite the increasing attention that sarcopenia has received in the field of oncology, particularly in relation to treatment tolerance and functional decline, most existing reviews have either focused on general cancer populations or included mixed age groups without specifically addressing older adults. Furthermore, considerable heterogeneity exists across studies regarding the diagnostic methods for sarcopenia, cancer types, and reported outcomes. To date, no systematic review has exclusively examined the association between sarcopenia and mortality in older adults with cancer using validated sarcopenia criteria. Given that individuals aged ≥65 represent the majority of cancer patients and are more vulnerable to adverse outcomes, there is a clear need to synthesize evidence specifically for this population. This systematic review aimed to synthesize current evidence of the association between sarcopenia and mortality in elderly cancer patients.

Methods:
We systematically searched PubMed, Web of Science, and Scopus up to October 29, 2024. The inclusion criteria encompassed observational studies reporting mortality outcomes in adults with cancer, with a mean age above 65 years and sarcopenia assessed using validated tools. Reviews, case reports, and studies lacking sufficient methodological quality were excluded. Two reviewers independently screened records and assessed methodological quality using the Joanna Briggs Institute checklist.

Results:
Nineteen studies comprising 6,555 participants were included. Most studies used CT at the L3 level to assess muscle mass, with sarcopenia prevalence ranging from 15.6% to 65.1%. Across studies, sarcopenia was consistently associated with increased overall or cancer-specific mortality. Reported hazard ratios ranged from 1.51 to 4.5, with the highest risk observed in patients with head and neck cancer. Quality assessment rated 15 studies as high-quality and 4 as moderate-quality.

Limitations:
The limitations of this review included heterogeneity in cancer types, diagnostic criteria, and follow-up periods, which may affect comparability across studies.