Prognostic significance of preoperative creatine kinase in resected thymic epithelial tumors.

ABSTRACT

Background: The preoperative serum creatine kinase (CK) concentration is a prognostic factor for malignant diseases. We investigated the significance of CK in surgically resected thymic epithelial tumors and the relationship between CK and clinicopathological factors. Methods: We retrospectively evaluated the relationship between preoperative CK levels and prognosis in 120 patients with thymic epithelial tumors who underwent surgical resection at two centers. The cutoff for CK was determined by the standard value in our institution (<62 IU/L for men and <45 IU/L for women). The paravertebral muscle at the Th12 level was used to assess skeletal muscle area to investigate sarcopenia. Results: Eighteen patients (15.0%) were categorized into the low CK group. The CK level was not associated with age, sex, performance status, myasthenia gravis, and pathological findings. Preoperative serum albumin and total cholesterol concentrations were significantly lower in the low CK group than in the normal CK group (both P<0.001). Moreover, the Th12 muscle index was lower in the low CK group (P=0.03), indicating that low CK was related to sarcopenia. Kaplan-Meier curve analysis illustrated that patients in the low CK group had significantly shorter disease-free survival (DFS) and overall survival (OS) than those in the normal CK group (P=0.03 and P=0.002, respectively). Multivariate analysis identified low CK as an independent prognostic factor for DFS (P=0.03) and OS (P=0.005). Conclusions: Preoperative serum CK might reflect the host nutritional status in patients with resected thymic epithelial tumors; therefore, CK could be a biomarker of postoperative prognosis.