Prospective Study of Immune Alterations in Operable Breast and Ovarian Carcinoma

This French research study collects blood and tissue samples from women undergoing surgery for ovarian or breast cancer to study how the immune system responds to these tumors. The goal is to identify immune markers that could predict treatment success. **You may be eligible if...** - You are a woman aged 18 or older - You are scheduled for surgery for high-grade serous ovarian cancer, grade II or III breast cancer larger than 3 cm, or extensive breast cancer in situ with an invasive component requiring mastectomy - You may have already received neoadjuvant chemotherapy (chemo before surgery) - You are covered by medical insurance **You may NOT be eligible if...** - You are under guardianship - You have a known inherited BRCA1/2 mutation - You have previously received immunotherapy (PD-1/PD-L1 or CTLA-4 inhibitors) - You are on immunosuppressant medications (other than low-dose steroids or inhaled/topical steroids) - You have a known autoimmune disease Talk to your doctor to see if this trial is right for you.