CRYO-1: Cryoablation in Elderly Patients With Early-Stage Breast Cancer.

CRYO-1 is a multicentre, phase II, single-arm interventional feasibility study evaluating cryoablation as a primary treatment for older adults with early-stage breast cancer. The study includes participants aged 70 years or older with clinically node-negative (cT1N0), estrogen receptor-positive, HER2-negative invasive breast cancer. Standard treatment for this patient population consists of surgery or primary endocrine therapy. Although effective, both approaches may be associated with treatment burden in older adults. Surgical treatment may result in perioperative morbidity, while primary endocrine therapy requires prolonged treatment and may be associated with side effects and the development of endocrine resistance. Cryoablation is a minimally invasive, image-guided technique that induces tumour destruction by freezing and may reduce treatment burden in selected patients. In this study, cryoablation is performed percutaneously under imaging guidance as a single procedure, without surgical excision of the primary tumour. The intervention is investigated as an alternative local treatment strategy in this selected population. The primary objective of CRYO-1 is to assess feasibility and acute safety of cryoablation. Feasibility is defined by successful completion of the procedure, and safety is assessed by the incidence of treatment-related adverse events within three months, graded according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Secondary objectives include technical success, need for additional locoregional treatment, early local tumour control, patient tolerance, and health-related quality of life. Exploratory objectives include longer-term oncologic outcomes and identification of factors associated with successful local control. CRYO-1 is an investigator-initiated study conducted across multiple hospitals. All participants provide written informed consent prior to enrolment. The study aims to generate prospective evidence on the feasibility and safety of cryoablation in older adults with early-stage breast cancer and to inform the design of future comparative or de-escalation studies.