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

Inclusion Criteria: * newly diagnosed hormone receptor positive, HER2 negative invasive breast cancer or DCIS with microinvasion, histologically confirmed, in postmenopausal patients older than 55 years, with primary tumour up to 3 cm and uninvolved axillary lymph nodes on clinical examination and on axillary ultrasound performed in Clinical Hospital Centre Rijeka. Patients should be eligible for breast conserving surgery and adjuvant whole breast irradiation. Exclusion Criteria: * Patients younger than 55 years of age and/or premenopausal, with cN1-3 status (confirmed cytologically or histologically), or with multiple suspicious lymph nodes on axillary ultrasound, regardless of cytological/histological confirmation. * Patients diagnosed with pure breast carcinoma in situ (DCIS) without focal invasion * Patients with tumour larger than 3 cm or with cT4 status, with de novo metastatic disease * Patients with a breast cancer of HER2+ or triple-negative immunophenotype * Patients who have received any type of neoadjuvant systemic therapy before surgery and those who have a previous personal history of invasive breast cancer * Patients with extensive multifocal or multicentric breast cancer, patients scheduled for mastectomy, partial breast irradiation or who refuse recommended adjuvant systemic oncological treatment * Patients who do not wish to participate in a clinical trial