5865 - Patients with a 21-gene assay in South East London differ from the TAILORx trial population

Background

The 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.

Methods

We 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.

Results

A 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.Table:

263P Patient characteristic

Conclusions

Our 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.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

C. 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.