Moreover, in a large retrospective study of 1012 breast cancer patients treated with FEC, variants in ABCC1/MRP1_rs4148350, ABCC1/MRP1_rs246221, and ABCC1/MRP1_45511401 showed a statistically significant correlation with FN, although only the first two were also associated with prolonged neutropenia [85]. This evidence concerns the gene ABCC1 and breast cancer.