ESR1 and metastatic neoplasm: Recent studies have reported a prominent ESR1 expression in smaller tumors, particularly enriched in HPV-positive OPSCC, and its association with a better prognosis in OPSCC, even independently of the HPV status, and suggested the addition of endocrine therapy for a safe dose reduction in cytotoxic treatment, particularly in HPV-positive OPSCC, or as an alternative systemic treatment that could address metastatic tumors [6].