Biomarker and in vitro chemoresistance profiles of undifferentiated ovarian cancers

2532 Background: To determine the biomarker expression and drug resistance patterns of undifferentiated ovarian cancers. Methods: Biomarker expression was determined by immunohistochemistry. In vitro drug resistance profiles were analyzed by assays exposing tumors to suprapharmacologic doses of chemotherapy. Results: Of 177 ovarian cancer specimens, 63 were classified as undifferentiated tumors and 114 well-differentiated cancers were used for comparison. Of the undifferentiated tumors, 46.7% were primary cancers and the remainder were recurrent cancers. Most of the well-differentiated tumors were obtained from primary (82%) vs. recurrent disease specimens. The average DNA index and S-phase fraction were significantly higher in the undifferentiated vs. well-differentiated tumors (1.42 vs. 1.23, p=0.025 for DNA index; 1.69 vs. 3.06, p<0.0001 for S phase fraction). In addition, the percent of tumors with p53 mutations was also higher in the undifferentiated compared to the well-differentiated tumors (47.8% ...