Clinical significance of the cachexia index in patients with small-cell lung cancer

Abstract Background: Cancer cachexia worsens the treatment outcomes of patients with small-cell lung cancer (SCLC). However, no reliable biomarker of cancer cachexia is yet known.Methods: We retrospectively evaluated SCLC patients who received induction chemotherapy or concurrent chemoradiotherapy. The cachexia index (CXI) was calculated as the skeletal muscle index × serum albumin level (g/dL)/the neutrophil-to-lymphocyte ratio. Male and female cutoffs were defined based on a time-dependent receiver operating characteristic curve, and all patients divided into low- and high-CXI groups.Results: Of 302 patients, 94 and 208 had low and high CXI values, respectively. Only one patient (1.1%) in the low-CXI group achieved a complete response (CR), whereas 35 of 208 patients (16.8%) in the high-CXI group achieved CRs (p < 0.001). More low-CXI patients (compared to the high-CXI patients) required early discontinuation of treatment because of treatment-related toxicity (20.2% vs. 6.3%, p < 0.001) and experienced treatment-related mortality (8.5% vs. 2.9%, p = 0.031). The median progression-free survival (PFS) and overall survival (OS) were significantly poorer in the low-CXI group than in the high-CXI group (5.8 vs. 6.9 months and 8.3 vs. 15.6 months, respectively, both p < 0.001). These differences did not vary according to cancer stage. On multivariate analysis, a low-CXI status was an independent poor prognostic factor for both PFS and OS.Conclusion: A low CXI was associated with treatment intolerance, a poor treatment response rate, and a poor prognosis of SCLC.