EGFR and mucositis: The rates of mucositis/stomatitis vary with the current EGFR TKIs, with incidence rates of 6% to 17% for gefitinib, 14% for erlotinib, 52% to 72% for afatinib, and 12% for osimertinib (Table 1; Thatcher et al., 2005; Mok et al., 2009; Sequist et al., 2013; Douillard et al., 2014; Genentech, 2015; AstraZeneca, 2015a, 2015b).