Unexpected Hair Growth Induced by Gefitinib Treatment in Two Patients with EGFR Gene Mutation-Positive Adenocarcinoma of the Lung

Gefitinib, an EGFR tyrosine kinase inhibitor used to treat non-small cell lung cancer with specific EGFR mutations, was reported to cause unexpected hair growth in two male patients with stage IV adenocarcinoma. Both patients, who had an in-frame deletion in exon 19 of the EGFR gene, experienced significant hair growth after starting gefitinib treatment, which also led to complete cancer remission. Case 1 saw more solid, abundant, and darker hair on the scalp, while Case 2 experienced new hair growth in a previously bald area. This side effect suggests a potential new therapeutic application of EGFR-TKIs for treating alopecia, as EGFR plays a crucial role in hair follicle development and growth.