Abstract P2-14-19: Patients’ experience with 70-gene signature testing on adjuvant systemic treatment decisions: Results of a prospective cohort study
Authors: van Steenhoven Julia E.C. , den Dekker Bianca , Kuijer Anne , Elias Sjoerd G. , van Diest Paul J. , Siesling Sabine , van Dalen Thijs 
Published: March 2020

Abstract
Background: Early stage breast cancer patients are often confronted with uncertainty regarding the decision to undergo adjuvant chemotherapy (CT). Gene-expression profiles (GEP) are used to gain additional prognostic information and can influence adjuvant systemic treatment (AST) decisions. Little is known about patients’ experience with systemic treatment decisions and the impact of GEP use.
Patients and Methods: In a prospective, observational, multicenter study in estrogen receptor (ER) positive (+) patients in whom a 70-gene signature (70-GS) was used to support the decision to administer adjuvant chemotherapy, patients were asked to fill out an online questionnaire including their preference for systemic treatment regimens. The patient reported uncertainty regarding the choice to undergo adjuvant systemic treatment was measured prior and after the 70-GS test result with the 16-item decisional conflict scale (DCS) scale.
Results: Between 1 January 2017 and 31 December 2018, 106 patients were enrolled. Fifty-four percent of patients had N0, grade I/II, HER2-negative breast cancers, while 40% had N+ cancers. Before the 70-GS results were available, 58% of patients formulated a clear treatment preference, whereas 42% of patients felt unsure regarding their systemic treatment decisions (Fig 1). After disclosure of the 70-GS test result the percentage of patients who felt unsure about their treatment preference decreased considerably (from 42% to 5%, Fig 2). In addition, the patients’ final treatment decision was changed to the opposite in 34% of patients (CT to no CT or vice versa). Prior to the 70-GS test result, the mean total DCS-score at baseline was 34 (out of 100) and decreased to 23 after release of the 70-GS test result (P&lt;0.001, table 1).
Conclusion: In this prospective, multicenter study in ER+/HER2- breast cancer patients, the use of the 70-GS strongly decreased the percentage of patients who felt unsure about their treatment preference, and changed patients’ CT treatment decisions for 34% of patients. Furthermore, use of the 70-GS resulted in a significant decrease in decisional conflict regarding their final treatment plan.
Table 1 CT preference and DCS-score prior and after release of the 70-GS test resultTreatment preference at baselineNo. of patientsTreatment preference after the 70-GS No. (%)DCS-score prior to 70-GSDCS-score after 70-GSP- value*No CT CT UnsureTotal1063423&lt;0.001No CT5339(74)13(25)1(1)CT98(89)1(11)-Unsure4431(71)9(20)4(9)Abbreviations: CT, chemotherapy, 70-GS, 70-gene signature, DCS, Decisional Conflict Scale. There was a change in 34% of patients who had a clear pretest CT preference (ie, yes or no CT). The mean total DCS-score decreased from 34 of out 100 to 23 after release of the 70-GS test result. *P-value represents a paired T-test.
Citation Format: Julia E.C. van Steenhoven, Bianca den Dekker, Anne Kuijer, Sjoerd G. Elias, Paul J. van Diest, Sabine Siesling, Thijs van Dalen. Patients’ experience with 70-gene signature testing on adjuvant systemic treatment decisions: Results of a prospective cohort study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-14-19.