Introduction/Background In an attempt to clarify prognostic relevance of poly-(ADP)-ribose polymerase(PARP) expression we analyzed clinical data of 86 high-grade epithelial ovarian cancer cases in which PARP immunohistochemistry results were available.

Methodology Immunostaining to highlight PARP protein expression was performed using a Leica Bond MAX Immunostainer (Leica Microsystems, Wetzlar, Germany). We applied the rabbit polyclonal anti-PARP antibody (ab6079 330, Abcam, Cambridge, UK) for the specific reaction. Intensity and distribution of immunostaining were assessed by light microscopy (Leica DM2500 microscope, DFC 420 camera, and Leica Application Suite V3 software; Leica) and evaluated with a four grade (0–3+) system. Median progression-free survival was generated for each semiquantitative group of PARP expression among chemotherapy-naive cases at the time of PARP immunohistochemistry.

Results Eighty-six cases were chemotherapy-naive at the time of PARP immunohistochemistry, and 41 of them showed no PARP expression. Forty-five cases showed intermediate or high PARP expression. The median progression-free survival among patient without PARP staining was 16 months (Interquartile range; IQR 10,7–35,9 months) and in the PARP positive group was 12 months (IQR 6,1–21,8 months). The difference was significant by Log-Rank test (p=0,01). The median OS was in the PARP negative group 65 months (IQR 43,6–110,8 months) and in the PARP positive group 52 months (IQR 36,9–66,7 months. The difference was significant by Log-Rank test (p=0,28). Multiple comparisons confirmed that PARP expression results in a significant difference in PFS and OS achieved by first-line taxol-carboplatin chemotherapy.

Conclusion The lack of PARP expression assessed by immunohistochemistry may predict longer progression free survival in ovarian cancer after adjuvant platinum based chemotherapy.

Disclosure Nothing to disclose.