Cryotherapy is a cold ablation technique used in many tumor locations. The destruction of tissues by cryoablation preserves proteins and in particular anti-tumor antigens, which could induce the stimulation of an immune response. Compared to other interventional radiology techniques, cryotherapy induces a higher immunogenic response. Studies describe complex responses with elevated levels of activating NK cells, circulating and anti-tumor T cells, and pro-inflammatory and NF-KB dependent cytokines.

In breast cancer, whether or not an immune response is triggered depends on the type of cryoablation used. Indeed, high intensity cryoablation (rapid freezing in one cycle of the entire tumor volume) seems to induce a tumor-specific immunodestructive response, whereas low frequency cryoablation (several small repetitive cycles until a sufficient volume of ice is obtained) does not induce an immunogenic response and can even induce an immunoregulation with immunotolerance of the tumor cells The University Hospital of Nîmes has recently acquired a new liquid nitrogen cryotherapy technique, more powerful than the one classically performed with Argon. This technique is used for palliative and analgesic purposes in patients with metastatic breast cancer presenting painful subcutaneous metastases. The aim of this study is to evaluate in these patients the changes in the tumor microenvironment and the immune response potentially induced by this very high intensity cryotherapy.

The study investigators hypothesize that locoregional treatment with liquid nitrogen cryotherapy of subcutaneous breast cancer metastases will allow a systemic response through the induction of an immune response. A better understanding of the type of immune response induced will allow the development of combined therapeutic strategies with curative and not only palliative and analgesic aims.

Inclusion Criteria:

• The patient must have given their free and informed consent
• The patient must be a member or beneficiary of a health insurance plan
• Patient with metastatic breast cancer with painful subcutaneous metastases.
• Patient eligible for cryotherapy.
• Therapeutic decision of antalgic and palliative treatment by cryotherapy taken in Pluridisciplinary Consultation Meeting.
• Patient available for 15-day follow-up.

Exclusion Criteria:

• The subject is in a period of exclusion determined by a previous study
• The subject us unable to express their consent or refuses to sign the consent form
• The patient is under safeguard of justice or state guardianship