Those who received G-CSF were more likely to receive high–FN risk regimens (commercially insured: 28 887 patients [72.9%] vs 8373 patients [17.8%]; Medicare: 6275 patients [83.0%] vs 1289 patients [6.2%]), with recent surgical procedures (commercially insured: 18 690 patients [47.2%] vs 18 315 patients [38.9%]; Medicare: 5055 patients [40.2%] vs 6345 patients [32.0%]), and neutropenia history (commercially insured: 6645 patients [16.8%] vs 2419 patients [5.1%]; Medicare: 3896 patients [31.0%] vs 3059 patients [15.4%]) . This evidence concerns the gene CSF3 and neutropenia.