ABCC1 and breast cancer: ABCC1 variants rs4148350, rs45511401, and rs246221 associated with the risk of febrile neutropenia in patients treated with 5-fluorouracil, epirubicin, and cyclophosphamide [40] and it was very recently discovered that ABCC1 variant burden is a strong predictor of DFS in breast cancer patients rather than the genotype attributed to individual variants [41].