EGFR and cancer: Recently, other researchers have indicated that As2O3 also inhibits EGFR expression in cancer cells through p21 activation leading to cell death via the EGFR-Ras-Raf-ERK1/2 pathway based on in vitro or ex vivo methods [27], [30], however, the in vivo therapeutic effects of As2O3 on pharyngeal OSCC tumors and the relationship of this response to EGFR expression detected noninvasively with NIR imaging has not been explored.