RECQL4 and breast cancer: The highest frequency of RECQL4 amplification was detected in ovarian cancer (10.14%; 120 of 1183 cases), melanoma (6.04%; 69 of 1142 cases), breast cancer (5.98%; 156 of 2609 cases), prostate cancer (3.68%; 80 of 2172 cases) and colorectal cancer (3.52%; 125 of 3548 cases) (Figure 1A).