Figure 6. The diagnostic performance of the developed multianalyte discriminant model for female SCLC in the discovery set. (A–E) Violin plots showed the relative levels of five selected metabolites in the female discriminant model. (A) PE (18:1/20:4); (B) 5-Methyltetrahydrofolic acid; (C) Desmosterol; (D) 4, 5-Dihydroorotic acid and (E) 9-HETE. (F) ROC curve analysis for distinguishing female SCLC patients from female NSCLC and controls. (G) The random permutation test to examine the robustness of the female discriminant model. (H) Multiple linear regression analysis showed a significant correlation between the five selected metabolites and NSE in female SCLC patients. R2 = 0.56, P < 0.05. Abbreviations: NSCLC = non-small cell lung cancer; PE = phosphatidylethanolamine; 9-HETE = 9-hydroxyeicosatetraenoic acid; ROC = receiver operator characteristic; SCLC = small cell lung cancer.