De-escalation in Axillary Surgery for Early-stage Breast Cancer

The goal of this clinical trial is to determine if the omission of sentinel lymph node biopsy is safe for early-stage breast cancer patients in our institution (Clinical Hospital Centre Rijeka). Targeted group are postmenopausal patients, older than 55 years, diagnosed with hormone-receptor-positive breast cancer, with primary tumour less than 3 cm and unaffected axilla on clinical exam and axillary ultrasound. The main questions we aim to answer are: * if this treatment de-escalation affects patient oncological outcomes (cancer recurrence)? * if this treatment de-escalation affects patient clinical outcomes (early and late complications related to axillary surgery)? * if this omission of pathological examination of sentinel lymph node affects recommendations on postoperative treatments (irradiation and systemic therapy)? Researchers will compare outcomes between participants submitted to sentinel lymph node biopsy and participants in whom the procedure is omitted to answer those questions. Participants will be asked to: * decide in which group they wish to participate * visit the clinic for checkups and tests once every 6 months in first two years and yearly thereafter up to 5 years