Is Age Trumping Genetic Profiling in Clinical Practice? Relationship of Chemotherapy Recommendation and Oncotype DX Recurrence Score in Patients Aged < 50 Years versus ≥ 50 Years, and Trends Over Time

Background: Oncotype DX (oDX) is used to predict recurrence and indicate response to chemotherapy in patients with early-stage breast cancer (BC). We evaluated the relationship between age (< 50 vs. ≥ 50 years), recurrence score (RS), chemotherapy use, and trends of oDX testing over time. Methods: Using the National Cancer Database, we identified women with T1/T2, N0, estrogen receptor-positive BC from 2009 to 2014. We stratified patients by age (< 50 and ≥ 50 years) and RS (low: < 18; intermediate: 18–30; and high: > 30), and compared demographics, tumor characteristics, and chemotherapy recommendations. Management trends were also assessed. Results: From 2009 to 2014, a total of 377,725 cases met the eligibility criteria for oDX testing; 115,052 (30.5%) patients had oDX, and 60,804 (16.1%) were < 50 years of age. The majority had low RS and T1N0 disease. Patients < 50 years of age were more likely to be recommended chemotherapy than those ≥ 50 years of age, regardless of RS (p ≤ 0.001), and were more likely to ultimately undergo chemotherapy (p < 0.001). When stratified by year, oDX utilization increased. There was a decreasing trend in chemotherapy recommendations in both the low- and intermediate-RS groups for both age groups (all p = 0.001), with no change in the high-RS group (< 50 years: p = 0.52; ≥ 50 years: p = 0.67). Univariate and multivariate analyses demonstrated that patients < 50 years of age and those with a higher RS were more likely to be recommended chemotherapy (p < 0.001). Conclusions: The testing of oDX in BC has significantly increased since first implemented. Results from additional studies such as TAILORx will clarify the current discordant practice patterns between low oDX RSs and adjuvant chemotherapy recommendations.