The sarcopenia index measured using the lumber paraspinal muscle is associated with prognosis in endometrial cancer

Abstract Background: The number of type-II endometrial cancer patients has been increasing and the prognosis is not favorable. We aim to investigate whether sarcopenia index in any of several different muscles could serve as a novel biomarker of prognosis in patients with type-II endometrial cancer.Methods: We retrospectively investigated a total of 194 patients at four hospitals. Ninety patients were treated as derivation set and the other 104 patients as validation set. Using preoperative CT images, we measured the horizontal cross-sectional area at the third lumbar spine level: the (i) psoas major, (ii) iliac, and (iii) paraspinal muscle. The clinical information including recurrence-free survival (RFS) and overall survival (OS) were retrospectively collected. These results were validated with external datasets of three hospitals.Results: The median values of the sarcopenia index (cm2/m2) ± SD with the first data of 90 patients using the psoas, iliac, and paraspinal muscle were 3.4 ± 1.0, 1.7 ± 0.6, and 12.6 ± 3.2, respectively. In univariate analyses, the sarcopenia indexes measured using the psoas or paraspinal muscle were associated with RFS and OS. On the other hand, in multivariate analyses, the sarcopenia index using paraspinal muscle was significantly related to RFS (hazard ratio (HR) 3.78, 95% confidence intervals 1.29–5.97, P = 0.009) and OS (HR = 3.13, 95% confidence interval 1.18–8.26, P = 0.022). Within the analysis of the validation set, sarcopenia index using paraspinal muscle was also related to RFS (HR = 2.06, P = 0.045).Conclusion: The sarcopenia index using the paraspinal muscle, not psoas, could be suitable index to predict RFS and OS in patients with type-II endometrial cancer.