Here, by analysing MFGE8 expression in large arrays of human tumor biopsies, and by establishing new functional assays to measure the effects of MFGE8 and of new MFGE8-blocking antibodies on the physiology of tumor cells, we identified ovarian carcinoma, and confirmed triple-negative breast carcinoma as promising targets which could benefit from MFGE8-inhibiting therapies. The gene discussed is MFGE8; the disease is triple-negative breast carcinoma.