Oncotype DX RS Correlation with Clinicopathologic Risk Factors and Chemotherapy: Follow up Based on TAILORx Study

Abstract Background: Oncotype DX risk score is a clinically validated prognostic and predictive molecular test. It estimates the recurrence and predicts the likelihood of benefit from adjuvant chemotherapy in early ER\PR positive, node-negative breast cancer. Patients are categorized into one of three tiers based on a calculated recurrence score (RS); low (<18), intermediate (18-30), and high (≥31-100) reflecting 10 years distant recurrence likelihood. 2008 NCCN guidelines recommended adjuvant endocrine therapy for low RS and adjuvant chemoendocrine therapy for high RS, but there was no clear recommendation of chemotherapy for intermediate RS (18-30). In 2018 the TAILORx re-established RS categories; a score of less than 11 is low, 11-25 is intermediate and 26-100 is high, and provided evidence to treat patients in intermediate RS category. Reviewing of Oncotype DX RS previous data in reference to TAILORx might support the optimal utility of this test which was suggested by the study. The Aim of the Study: Look for Oncotype Dx RS correlation, with clinical and pathological risk factors (age, tumor size, tumor grade, ER/PR status, tumor proliferation index) and chemotherapy based on TAILORx RS tier. Study the characteristics of patients who had cancer recurrence. Method: Retrospective data review of 54 patients who had Oncotype DX test during 2012-2017 at National Cancer Center-Qatar. Result: Of 54 patients studied 16(29.63%) had low RS, 32(59.26%) had intermediate RS, and 6(11.1%) had high RS. Univariate analysis showed that age (p<0.014), tumor grade (p<0.034), and Ki67% (cut-off 20%; p<0.013) were significantly different among Oncotype DX RS categories. There was no significant difference among Oncotype DX RS categories for tumor size (p<0.288) or PR status (cut-off 1%, p<0.3). Multivariate analysis showed that none of the clinical/pathological factors significantly predict the Oncotype DX RS. Chemotherapy was given to 1/16 (6.25%) patients with low, 7/32(21.9%) patients with intermediate, and 4/6 (66.7%) patients with high Oncotype DX RS (univariate analysis p<0.01). Although Oncotype DX RS had significant association with chemotherapy in univariate analysis, tumor size was the only predictor of adjuvant chemotherapy treatment from all factors including Oncotype DX RS (OR 2.33 CI 0.33 - 3.86, p<0.020). The majority (75%) of patients who had disease recurrence belonged to the high intermediate (16-25) Oncotype DX tier, and all were less than 50 years old in age. Conclusion: Oncotype RS correlates significantly with individual clinical risk factors including age, tumor grade, Ki67%, chemotherapy treatment. Tumor size significantly predicts adjuvant chemotherapy. Breast cancer recurrence was noticed in younger patients with high intermediate RS (16-25), and adjuvant chemotherapy may be a reasonable option for these patients.