Researchers have endeavored to identify unique molecular features of secondary oral primary cancers to aid in clinical diagnosis, such as tumor suppressor genes (p53, p14, p73), FAS/FASLG, p21, p27, and oncogenes (MDM2, MDM4), which may serve as effective molecular markers for MPCs.14,15,16,17,18 Furthermore, aberrant methylation levels of CCNA1 and TIMP3 have also been implicated in the development of MPCs.19 However, conclusive evidence supporting these associations is currently lacking. The gene discussed is CDKN2A; the disease is cancer.