179P - A nomogram for predicting the Oncotype DX recurrence score in women with T1-3N0-1miM0 hormone receptor-positive, human epidermal growth factor-2 (HER2)-negative breast cancer

Abstract

The aims of this preliminary study were to evaluate the association between the Oncotype DX (ODX) recurrence scores and traditional prognostic factors and to develop a nomogram that predict a subgroup of patients with low ODX recurrence scores (≤25), in whom addition of chemotherapy can be avoided. Clinicopathological and immunohistochemical variables from a series of 396 T1-3N0-1miM0 hormone receptor-positive, human epidermal growth factor-2 (HER2)-negative breast cancer patients with available ODX test results at Asan Medical Center from 2010 to 2015 were retrospectively retrieved and analyzed. One hundred eight (27%) had positive axillary lymph node micrometastases, and 333 (84%) had ODX recurrence scores of ≤25. Logistic regression was performed to build a nomogram for predicting a low-risk subgroup of the ODX assay. The cutoff value of ODX recurrence scores for the low-risk subgroup was set at 25, which is used in the ongoing Oncotype DX phase 3 TAILORx trial. Multivariate analysis revealed that estrogen receptor (ER) score, progesterone receptor (PR) score, lymphovascular invasion (LVI), nuclear grade, and Ki-67 had statistically significant association with the low-risk subgroup (all p values < 0.001). With these variables, we developed a nomogram to predict the low-risk subgroup with the ODX recurrence scores of ≤25. The area under the ROC curve was 0.90 (95% CI, 0.85-0.96). Low ODX recurrence score subgroup can be predicted by a nomogram incorporating five traditional prognostic factors: ER, PR, LVI, nuclear grade, and Ki-67. An independent prospective validation for the present nomogram is underway to confirm its accuracy.