The ASCO and IDSA Clinical Practice Guideline Update recommend in favor of antibiotic prophylaxis using a fluoroquinolone in patients who are at high risk for FN or profound, protracted neutropenia especially in hematological malignancies, but not routinely in solid tumors and when G-CSF prophylaxis effectively reduces the depth and duration of neutropenia [27]. This evidence concerns the gene CSF3 and neutropenia.