ESR1 and lung cancer: Previous studies have detected estrogen receptors in both normal and cancerous lung tissues [10, 11], higher rates of epidermal growth factor receptor (EGFR) mutation-positive lung cancer in never-smoking women [12], familial aggregation of reproductive cancers among female lung cancer patients [13, 14], and increased lung cancer risk in female cancer survivors with a history of reproductive-related primary tumors [15–21].