One study showed that the SHMT1 C1420T polymorphism was associated with laryngeal squamous carcinoma (LSC) (42), and although there are no studies on the function and mechanism of action of SHMT1 in HNSCC, SHMT1 has been shown to be an oncogene in both lung and ovarian cancers (43, 44). Here, SHMT1 is linked to head and neck squamous cell carcinoma.