In patients with Her-2 breast cancer (ER-/PR-/HER2+) or triple negative breast cancer (ER-/PR-/HER2-), tumor samples with enriched cholesteryl ester accumulation were associated with increased expression of the cell proliferation marker, Ki-67, thus indicating the potential for enhanced tumor proliferation and progression. The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.