Here, we focused on the relationship between chemo-responsiveness and the changes in diversity index during chemotherapy using c-MYC which is located at one of the most unstable chromosomal regions (8q24) and frequently harbors copy number gain or amplification in breast cancer regardless of subtype18–20, in an attempt to find the clinicopathologic significance of post-treatment genetic diversity. This evidence concerns the gene MYC and breast carcinoma.