Omission of Breast Surgery for Breast Cancer Patients With pCR on MRI and Vacuum-assisted Biopsy After NST (OPTIMIST)

This study is exploring whether women with breast cancer who respond very well to pre-surgery chemotherapy — so well that scans and biopsies show no remaining tumor — can safely skip breast surgery altogether. Instead of surgery, researchers will use MRI and needle biopsy to confirm the cancer is gone. **You may be eligible if...** - You are a woman aged 20 or older - You have been diagnosed with HER2-positive or triple-negative invasive ductal carcinoma (a specific type of breast cancer) - Your initial tumor was 5 cm or smaller with no widespread lymph node spread - Your MRI after chemotherapy shows very little or no remaining tumor - A small metal clip was placed in your tumor before or during chemotherapy - You have no signs of cancer spread to other parts of the body **You may NOT be eligible if...** - You have cancer in multiple spots in the same breast, or cancer in both breasts - You carry a BRCA gene mutation - You want to have breast surgery - You have had another cancer in the last 5 years - You are allergic to MRI contrast dye - You have inflammatory breast cancer Talk to your doctor to see if this trial is right for you.