Comparing lung cancer patients with benign group, the best cutoff level of MMP-2 in BALF for SCC, ADC, and SCLC were 1.794 ng/ml, 1.643 ng/ml, and 0.906 ng/ml, corresponding AUC was 0.7458 (95% CI, 0.6097–0.8820), 0.7708 (95% CI, 0.6513–0.8904), and 0.7396 (95% CI, 0.5937–0.8854), respectively (Figure 4B–4D). The gene discussed is MMP2; the disease is small cell lung carcinoma.