Previous studies have shown that deficiency of BRCA1, a client to Hsp90, sensitize cells to 17AAG treatment [28], and since tumor cells expressing high levels of BRCA1 are intrinsically resistant to irradiation and several chemotherapeutics [28, 29], Hsp90 inhibitors could be used in a therapeutic strategy in treatment regimens activating a DNA damage response. This evidence concerns the gene BRCA1 and neoplasm.