Indeed, a systematic review that analyzed 80 studies published between 1959 and 2022 [29] showed improvement in the number and severity of oral lichen planus lesions in patients prescribed with vitamin D supplements [30], reduced tumor volume of oral cancer xenografts in mice co-treated with erlotinib (an epidermal growth factor receptor inhibitor) and 1,25-(OH)2D3 [16], and synergic effects of 5-fluorouracil and 1,25(OH)2D3 on human oral squamous cell carcinoma lines (C152) viability [31]. Here, EGFR is linked to lip and oral cavity carcinoma.