263P - Patients with a 21-gene assay in South East London differ from the TAILORx trial population

Abstract

BackgroundThe 21-gene Breast Recurrence Score® (RS) is an established genomic tool to assess recurrence risk and adjuvant chemotherapy benefit in early breast cancer. The TAILORx study redefined group boundaries of the RS in node negative women. In the 668 patients of the NSABP-B14 study that formed the validation set of the RS younger age was significantly correlated with distant recurrence and tumour size trended toward significance. High tumour grade remained an independent prognostic factor beyond the RS. In the TAILORx study these higher risk groups were under-represented. MethodsWe compared clinical prognostic parameters of women in South East London with available RS with the TAILORx trial population. Retrospective case note analysis of all identified patients between 2013 and 2018 was completed. Women with nodal involvement were excluded. Descriptive statistics were used for comparison with patient characteristics of the TAILORx study. ResultsA total of 269 tests were identified. 42 were excluded for nodal involvement or incomplete clinical data, leaving 227 patients. Differences between the populations are demonstrated for all characteristics and will be presented at the meeting.Table263P Patient characteristicTableRS<1111-25>26ALLN (%)34 (11)142 (67)51 (22)227 (100)Median age (range)48 (28-75)49 (28-74)53 (38-78)50 (28-78)≤50yr %56564152Premenopausal %59644759Tumour size in cm Median (IQR) Mean (SD)2.0 (1.7-3.0) 2.6 ± 1.52.1 (1.5-3.0) 2.6 ± 1.82.2 (1.6-3.0) 2.4 ± 1.22.1 (1.6-3.0) 2.6 ± 1.6Tumour grade %LowIntermediateHigh67421463330247645641Clinical risk %LowHighHigh (TAILORx)3565223268262080573070 ConclusionsOur patients have a higher clinical risk than the TAILORx population. They are younger and have larger, higher grade cancers. This population is under-represented in the TAILORx study which was unable to exclude benefit in the ≤ 50 subset and may thus underestimate benefit from chemotherapy in our population. The current RS reporting is biased towards an older, low-risk population. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureC. Gousis: Travel / Accommodation / Expenses: Roche. H. Kristeleit: Advisory / Consultancy, Speaker Bureau / Expert testimony, Travel / Accommodation / Expenses: Novartis; Advisory / Consultancy, Speaker Bureau / Expert testimony: Eisai; Advisory / Consultancy: Roche. All other authors have declared no conflicts of interest.