Sarcopenia (low skeletal muscle index, SMI) and myosteatosis (low skeletal muscle radiodensity, SMD) have been associated with worse survival in cancer. This study evaluated associations of body composition with survival in patients with resected stage III melanoma.
A retrospective review was performed of resected stage III melanoma patients in Alberta, Canada from 2007 to 2017. Preoperative CT scans were analyzed to determine SMI and SMD. Cohort-specific SMI and SMD cut-offs that optimally predicted overall survival (OS) were identified through stratification, in addition to testing cut-offs previously established in the literature. Overall (OS), melanoma-specific (MSS), and recurrence-free survival (RFS) were determined from date of surgery and analysed using multivariable Cox regressions with age, sex, BMI, stage subgroup, ECOG PS, and tumor location as covariates.
We included 330 patients in the final analysis. Mean age was 56 years and 62.4% of patients were male. At time of censoring 150 patients (45.6%) had died. Sarcopenia based on literature cut-offs was associated with decreased OS (HR 1.55, 95% CI 1.00-2.21, p = 0.016). Using cohort-specific cut-offs, sarcopenic patients also had significantly decreased OS (HR 1.87, 95% CI 1.27-2.76, p = 0.002). Myosteatosis defined using cohort-specific cut-offs predicted worse OS (HR 2.15, 95% CI 1.42-3.25, p < 0.001), MSS (HR 2.29, 95% CI 1.40-3.75, p = 0.001) and RFS (HR 1.52, 95% CI 1.02-2.27, p = 0.041). Increased BMI ( ≥ 25) and visceral fat index were not significantly associated with survival.
Sarcopenia and myosteatosis, defined using two sets of cut-offs, are associated with decreased OS and MSS in resected stage III melanoma.

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