Gene expression profiles of malignant carcinomas surgically removed from ovarian cancer patients pre-treated with chemotherapy (neo-adjuvant) prior to surgery group into two distinct clusters. One group clusters with carcinomas from patients not pre-treated with chemotherapy prior to surgery (C-L) while the other clusters with non-malignant adenomas (A-L). Although the C-L cluster is preferentially associated with p53 loss-of-function (LOF) mutations, the C-L cluster cancer patients display a more favorable clinical response to chemotherapy as evidenced by enhanced long-term survivorships. Keywords: Patient Tumor Samples Overall design: A set of 43 ovarian tumors was obtained from the Ovarian Cancer Institute (Atlanta). Tissue was collected at the time of surgery and preserved in RNAlater (Ambion, Austin, TX) within one minute of collection. Labeled probe was hybridized to the Affymetrix HG-U95Av2 arrays.