[1096] Personalized Treatment of Ovarian Cancer: The Role of the Pathologist

DE Westfall, B Karlan, D Barbuto, EG Silva. Cedars-Sinai Medical Center, Los Angeles, CA

Background: Personalized treatment of ovarian cancer is a new approach based on individual biological differences in the molecular characteristics of tumors. Immunostains identify receptors and proteins that may be therapeutic targets. Pathologists play a key role in selecting blocks on which to perform these stains. However, there are no established guidelines to select appropriate sections for immunostains.
Design: We randomly selected 10 high grade serous carcinomas (Cas) including nine ovarian and one fallopian tube Ca, each with > 2 metastatic foci. Three blocks from each of the primary Ca and metastases (Mets) from each case were stained with epidermal growth factor receptor (EGFR), estrogen receptor (ER) and progesterone receptor (PR). Stains were evaluated for percentage of positive cells and intensity of staining, on a scale from 1+ to 4+.
Results: There were no differences in the intensity of staining; however, there were significant differences in the percentage of positive cells. EGFR staining of primary Cas showed an average of 3 fold (maximum 7 fold) difference from area to area. EGFR staining of Mets showed four cases with relatively equal percentages of positivity as the primary, four cases with higher percentages of positive cells and two cases with lower percentages of positive cells. ER staining showed an average of 2 fold (maximum 5 fold) variation within primary Cas. Of Mets stained with ER, nine were similar to the higher staining areas in respective primary Cas and one had a lower percentage of cells staining positive than in the primary. Primary Cas stained with PR showed an average of 5 fold (maximum 10 fold) variation, with Mets showing a similar percentage of cells staining positive in nine cases and a higher percentage of cells staining positive in one case, when compared to the highest staining pattern observed in the primary.
Conclusions: 1) There are significant variations in immunohistochemical staining characteristics between different areas of Mllerian Cas 2) EGFR showed significant variations in staining patterns within the primary lesion as well as between primary and metastatic lesions. 3) ER and PR had similar staining in the primary and Mets when comparing areas with the highest staining patterns, but still had significant variations in different areas of the primary Ca. 4) We recommend selecting more than one section from the primary and metastatic site whenever possible to assess applicability of targeted therapy. Differences in staining patterns should also be taken into consideration when evaluating the results of treatments.
Category: Gynecologic

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 161, Wednesday Morning