• Radiofrequency ablation (RFA) – is a minimally invasive procedure that uses electrical energy and heat to destroy cancer cells. A needle is inserted through the skin into the cancer tissue and the heat produces coagulation necrosis and subsequent cell death. While RFA is a simple, repeatable, standardized, lower risk procedure, it is limited by only having a small area of effectiveness since electrical impedance develops as the tissue boils and becomes charred.⁴ This insulates the tissue from the electrical signal and results in an effective area of only few millimeters. Besides tumor location, other factors which impact the effectiveness of RFA include the size and number of tumors and the need for a large tumor-free margin. While RFA is not typically used as a first-line treatment for breast cancer, it may be considered in certain cases, particularly for small tumors or as part of a multidisciplinary treatment approach. It is more commonly used for the treatment of benign breast tumors, such as fibroadenomas.

• Microwave ablation (MWA) – MWA uses high frequency microwave energy to heat and kill cancer cells. A thin probe containing an antenna which emits microwaves is into the tumor. The probe produces intense heat that destroys tumor tissue via coagulation necrosis, often within 10 minutes. In the context of breast cancer, MWA is a minimally invasive technique that has been investigated as a potential treatment option, particularly for small tumors. MWA is not commonly used as a primary treatment for breast cancer, but it has been explored in clinical studies and research settings.

• Cryoablation –  Cryoablation or cryosurgery that uses extreme cold to destroy tumors. The procedure causes rapid cooling of the target tissue, resulting in intracellular ice crystal formation that destroys organelle and cell membranes and induces membrane pore formation that disrupts the electrochemical gradient. Cellular tonicity is also disturbed, causing lethal transmembrane fluid shifts. If these changes do not cause immediate cell death, they often initiate apoptosis. The ability to visualize ice ball formation, the edge of which marks the 0°C isotherm, in cryoablation on several imaging modalities is a particular benefit. Cryotablation’s role in the treatment of breast cancer has not been established.

• High-Intensity Focused Ultrasound (HIFU) – HIFU is a non-invasive therapeutic technique that uses ultrasound waves to treat various medical conditions, including breast cancer. In the context of breast cancer treatment, HIFU is sometimes used as a focal therapy to target and destroy cancerous tissue without the need for surgery. HIFU works by focusing high-intensity ultrasound waves on a specific target within the body. The focused ultrasound energy generates heat, causing thermal ablation (destruction) of the targeted tissue.

During a HIFU procedure for breast cancer, the patient is positioned such that the ultrasound waves can be accurately targeted at the tumor. Real-time imaging, such as ultrasound or MRI, is often used to guide the HIFU treatment and monitor its progress.