FOXD3-AS1 yielded an AUC of 0.906 (95% CI: 0.831–0.982), a sensitivity of 73%, a specificity of 92%, and a Yoden index of 3.94 in distinguishing between SCLC and HS subjects (Figure 5(a) and Table 4). This evidence concerns the gene FOXD3 and small cell lung carcinoma.