Impact of OncoType DXTM Recurrence Score and Tumor Size on Making Chemotherapy Decisions in Breast Cancer Patients.

Abstract

Abstract Background: Oncotype DXTM is a 21 gene assay that calculates recurrence score(RS) and recurrence risk(RR) over 10 years. Despite the contention that this genomic assay is more accurate than tumor size(TS) and age in predicting outcome, these factors continue to have major impact in decision-making regarding chemotherapy(CT). We analyzed the impact of TS, RS, and age on the decision to give CT.Methods: An IRB-approved chart review of 105 lymph node(LN) negative patients with ER+ T1 and T2 tumors was performed, reviewing age, RS, TS, CT history, Her-2 status, and pathology. RS was low(0-17), intermediate(18-30), or high(>30). TS was divided into T1a(0.1-0.5 cm), T1b(0.51–1.0 cm), T1c(1.1–2.0 cm), and T2(2.1-5.0 cm).Results: Mean patient age was 60.9 years(range 35-82 years). Average(AVG) RS was 20.9; AVG RR at 10 years, 13.6%. Mean TS was 1.5 cm(median 1.3 cm). Overall, 29 patients(27.6%) received CT; 76(72.4%) did not. AVG TS for CT patients was 1.8cm, AVG RS was 29.5, and AVG age was 56.4(range 35-75). Non-CT patients' AVG TS was 1.4cm; AVG RS, 17.7; AVG age, 62.6(range 44-86). 9 patients(8.5%) had T1a tumors with an AVG RS of 19.1, and no patient received CT. 25(23.8%) had T1b tumors with an AVG RS of 21.0, and 5(20.0%) received CT. 51(48.6%) had T1c tumors with an AVG RS of 20.4, and 15(29.4%) received CT. 20(19.0%) had T2 tumors with an AVG RS of 23.1; 9(45.0%) received CT. 41 patients(39.0%) had low RS: 4(9.8%) received CT; 37(90.2%) did not. AVG TS and RS were 1.6cm and 15.0 respectively for CT patients, and 1.5cm and 11.6 for no CT patients. 49 patients(46.7%) had intermediate RS: 13(26.5%) received CT; 36(73.5%) did not. AVG TS and RS were 1.9cm and 22.7 for CT patients; 1.3cm and 22.2 for no CT patients. 15 patients(14.3%) had high RS: 12(80.0%) received CT; 3(20.0%) did not. AVG TS and RS were 1.7cm and 44.7 for CT patients; 1.3cm and 39.3 for no CT patients. 10 patients were Her-2+, 5 with high, 4 with intermediate, and 1 with low RS. 7 had CT. 5 of the 15(33.3%) high RS patients were Her-2+. AVG RS for the Her-2+ patients was 36.2, and AVG TS was 1.9cm. AVG RS was 19.3 for the non-Her-2+ patients. 16 patients were <50 years old. AVG TS was 1.5cm and AVG RS was 24.2. 8 received CT and 8 did not. 89 patients were ≥50. AVG TS was 1.5cm and AVG RS was 20.3. 21(23.6%) received CT and 68 did not. Discussion: AVG RS was 20.9 for all T stages. Overall, 27.6% of patients received CT. Of the 64 with RS>18, only 25(39.1%) received CT; 4(9.8%) of low RS patients still received CT. Patients with larger tumors and younger age were more likely to receive CT. Neither RS, TS, nor age alone seemed to influence the final decision. Multiple factors are still considered by oncologists when making CT decisions, and conversely, patients may not accept CT despite high RS. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 6039.