Ki-67 Proliferative Index in Estrogen Receptor-Positive/HER2-Neu Negative Early Breast Cancer Predicts Oncotype DX Recurrence Score
C Kelly, RS Saad, S Nofech-Mozes, H Kahn, J Zubovits, J Wong, WM Hanna. Sunnybrook Health Sciences Center/University of Toronto, Toronto, ON, Canada
Background: Oncotype DX assay is a useful tool to calculate the risk of recurrence in early breast cancer patients, with prognostic and therapeutic implications. However, the cost of the assay may not be affordable by many patients, leading us to search for more cost effective method. We examined relation between the histopathologic variables, hormonal receptors IHC score, Ki-67 proliferation index as predictors for Oncotype DX recurrence score in estrogen receptor (ER)-positive, Her2/neu negative early breast cancer patients.
Design: Slides and surgical pathology reports from 84 cases of breast carcinomas evaluated by Oncotype DX were retrospectively reviewed to determine patient age, tumor size and histologic grade. All cases were LN negative, ER positive and Her2/neu negative. Cases were immunostained for Ki67 proliferative marker. Estrogen and progesterone receptors (ER and PR) and Ki67 were reported as a semi-quantitative score reflecting the proportion of positive cells.
Results: Eighty four patients were included in the study, age range 38-74 with a mean 51+8 yrs. Onctotype DX recurrence score (RS) were divided into low risk 42/84 (50%) cases, intermediate risk 27/84 (32%) and high risk in 15/84 (18%) cases. The value of Ki67 index was follows: 16+10 in Low risk group, 37+12 in intermediate and 60+11 in high risk group with significant difference (P< 0.001). On histologic examination, 17/84 (20%) showed low histologic grade, 56/84 (67%) intermediate grade and 11/84 (13%) cases high histologic grade. Lymphovascular invasion was identified in 18/84 (21%) cases. PR was negative in 8/84 (10%). There was significant correlation between RS and Ki67 (r=0.75, P< 0.0001), high histologic grade (r=0.41, P< 0.001), and negative staining with PR (r=0.48, P< 0.001).
Conclusions: The present study shows the importance of cell proliferation as a determinant of biologic behavior of breast cancer in ER positive/Her2neu negative early breast cancer. Measurement of ki-67, histologic grade, and PR negativity are correlated with RS and may be helpful for physicians to detect high-risk patients and to adopt appropriate procedure such as adjuvant therapy.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 31, Tuesday Afternoon