In the context of breast cancer, in case of an indication for chemotherapy, anthracycline-based protocols make it possible to improve the overall survival of patients most at risk. The frequency of anthracycline-related cardiac toxicities (ARCT) increases with the cumulative dose of anthracyclines administered and explains, at least in part, the increased risk of cardiovascular (CV) mortality in patient populations treated for breast cancer. The numerous indications for anthracycline-based protocols have made it possible to describe ARCT, among which heart failure with reduced left ventricular ejection fraction (LVEF) remains one of the most comorbid. In addition to left ventricular dysfunction, anthracyclines have been associated with endothelial dysfunction, microvascular damage and myocardial ischemia responsible for dilated cardiomyopathy.

Different approaches have attempted to better understand and prevent these ARCT. However, apart from the notion of limit cumulative doses of anthracyclines, few of them have made it possible to screen patients at risk and prevent the onset of cardiac dysfunction. The search for biological markers (Troponin I, BNP) or ultrasound markers (Longitudinal Strain) warning of subclinical cardiac damage is still struggling to assert its interest due in particular to significant inter- and intra-observer variability. Therapeutically, ACE inhibitors and beta-blockers have shown a significant improvement in the incidence rate of LVEF reduction during adjuvant treatment of breast cancer. However, despite equivalent signals in other cancers, the studies conducted to date are insufficiently powered and the role of these treatments is limited to secondary prevention or the treatment of objective heart failure. It remains necessary to determine new biological markers that can identify patients most at risk of ARCT and thus adapt our therapeutic prevention strategies. To do this, it is first necessary to better understand the pathophysiology underlying these ARCT.

The objective of this study is to determine whether expression of the receptor among endothelium and circulating cells, SGLT2, is associated with an additional risk of presenting cardiovascular toxicity following treatment with anthracycline. If this association is demonstrated, it will then be possible to better screen and prevent these cardiovascular complications.

Inclusion Criteria:

• Patient > 18 years old
• Diagnosed with localized breast cancer
• Indication for first-line surgery or anthracycline-based chemotherapy.

Exclusion Criteria:

• History of chemotherapy or targeted therapy or immunotherapy administered before inclusion
• Patient currently being treated with anti-SGLT2, conversion enzyme inhibitor or ARA2
• Patient with known heart disease (ischemic, rhythmic, valvular, etc.)
• Patient with a Glomerular filtration rate < 45 mL/min/1.73m² according to the pre-therapeutic assessment
• Patient with impaired liver function
• Patient who is pregnant or breastfeeding
• Patient with a second cancer undergoing treatment
• Patient under guardianship or curatorship, protection of justice or deprived of liberty

The recruited population concerns adult patients followed for localized breast cancer and for whom treatment with anthracycline is indicated in the adjuvant or neoadjuvant situation.