SHOX2 and squamous cell carcinoma: Based on previous studies, short stature homeobox 2 (SHOX2) gene DNA was confirmed to have higher methylation levels in patients with small cell lung cancer (SCLC) and squamous cell carcinoma (SCC) than in patients with adenocarcinoma (Ade) and in healthy controls [14–16], indicating its potential as a diagnostic biomarker for specific types of lung cancers.