Abstract
Abstract
Objectives
Oncotype Dx is a multigene assay used to determine the recurrence risk and predicts the benefits of chemotherapy in invasive breast cancer patients (BCPs) with positive estrogen receptor (ER), negative HER2, and negative node. The aim of this study is to determine the correlation between the BCP pathological parameters (PPs) and the Oncotype Dx recurrence score (ORS) for a better selection of patients for Oncotype Dx testing.
Methods
A retrospective analysis of 187 patients who underwent Oncotype Dx testing (Genomic Health, Redwood City, CA) between 2012 and 2017 in two tertiary hospitals in Saudi Arabia (King Faisal Specialist Hospital and research center and King Abdulaziz Medial City). The PPs: tumor cell type, tumor grade (TG), mitotic score (MS), ER, progesterone receptor (PR), HER2 status, and Ki-67 proliferation index (KI-PI), which was categorized into low (>10% to <25%) and high (>25%). These parameters were correlated with the ORS.
Results
Most of the tumors in our study population were of the ductal cell type (95.7%), and the rest were the lobular cell type (4.2%). ORS result was distributed as follows: low risk (53.4%), intermediate risk (35.29%), and high risk (11.2%). In univariate analysis, there was a significant linear correlation between ORS and TG, as well as MS and KI-PI. However, an inverse correlation was observed between positive expression of PR and ORS. In a multivariate analysis, tumor grade, PR status, and KI-PI had a significant correlation. A strong linear correlation was observed between ORS and Ki-67 categories: 84% of cases with low-risk ORS had a Ki-67 <25% while most of the high-risk ORS (85.7%) had a Ki-67 of >25% (P < .005).
Conclusion
There is a significant correlation between BCP-PP—namely, TG, PR status, and KI-PI and ORS in our study population. High TG, either low or absent PR expression, and KI-PI of >25% are more likely associated with high-risk ORS.