Effectiveness of primary endocrine therapy in older adults with estrogen receptor-positive breast cancer: A real-world audit of a dedicated primary endocrine therapy clinic

Breast cancer incidence rises steeply with age; in the United Kingdom a quarter of new diagnoses occur in women aged 75 years and over, a group frequently characterised by frailty, multimorbidity, and heightened surgical risk [1–3]. Primary endocrine therapy (PET), the use of endocrine agents without surgical intent as the primary local treatment for hormone receptor-positive disease, is an established option for those unsuitable for or declining surgery, with aromatase inhibitors, particularly letrozole, now the first-line agents [4].