Abstract P3-08-46: Correlation of prognostic indicators based on clinical and pathological features in hormone receptor positive and HER2 receptor negative early breast cancer with the 21 gene assay recurrence score

Background: With the advent of genomic testing in routine practice to predict the benefit of adjuvant chemotherapy, in a resource limited health service, many multi-disciplinary breast cancer teams are relying on known clinical and pathological factors to determine which patients undergo testing or to avoid/receive chemotherapy in hormone receptor positive, HER2 negative (HR+, HER2 -ve) breast cancer. These factors are manipulated in formulae or in online prognostic calculators to determine "risk". Oncotype DX Recurrence Score® is routinely used in the UK to determine benefit of adjuvant chemotherapy in early breast cancer according to National guidelines (NICE) which determines risk using the Nottingham Prognostic Index (NPI) and Predict. Methods: With the kind permission of surgical and oncology colleagues within the Wales Cancer Network Breast Clinical Site Group, all patients with HR+, HER2-ve invasive breast cancer who had undergone Oncotype DX Recurrence Score® testing between 31/10/15 and 1/11/18 were matched to the prospectively held national cancer database. Post- operative tumour size, grade, nodal status, age of patient and route of diagnosis were then utilized to calculate the NPI for each case and the PREDICT! on line calculator for chemotherapy benefit in addition to endocrine therapy. A correlation co-efficient was then calculated for NPI, PREDICT 5 and PREDICT 10 to the recurrence score®. Ki 67 is not routinely calculated. Results: There were 734 cases with a RS® available matched to the cancer registry database, 96 of which had missing data items preventing calculation of NPI or PREDICT! values. Conclusions: This is the largest cohort analysis in the UK of recurrence score testing published to date and covers a wider range of node negative, micro metastatic and node positive patients. We have demonstrated a weak correlation between the RS® and the NPI or PREDICT outcome in predicting benefit of chemotherapy and we do not believe these clinic-pathological surrogates should be relied upon to determine indications for adjuvant chemotherapy in HR+, HER2-ve early breast cancer patients or in determining if Oncotype DX Recurrence Score® testing should be performed in order to reduce over treatment with chemotherapy. Citation Format: Marianne Dillon, Adam Yarwood, Daniel Thomas, Wales Cancer Network Breast Clinical Steering Group. Correlation of prognostic indicators based on clinical and pathological features in hormone receptor positive and HER2 receptor negative early breast cancer with the 21 gene assay recurrence score [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 P3-08-46.