Double Breast Neoplasia: RH+, HER2- Metastatic Left Breast Cancer and Triple Negative Metastatic Right Breast Cancer: Case Report

Breast cancer is the most common cancer in women, and the proportion of metastatic cancer is not negligible; either metastasis of a cancer that was initially localized, or metastatic disease from the outset. The case of double breast neoplasia is not exceptional; but when faced with two breast cancers, both metastatic, and with different molecular profiles, several questions arise. Case report: We report the case of a diabetic patient with localized RH+, HER2- left breast cancer treated with surgery and adjuvant chemotherapy in 2003, which became metastatic to the lung in 2022, and for which the patient received hormone therapy + anti CDK4/6. In the same month as the pulmonary lesions were discovered, a right breast cancer was diagnosed, biopsied as triple-negative; this metastasized to the brain in 2024. Conclusion: the problem in this case concerns the rarity of occurrence of two metastatic breast cancers for the same patient, the complexity of therapeutic management, and makes us think about intra-tumoral heterogeneity in breast cancer.