Abstract 9P
Background
CanAssist Breast (CAB) is an IHC based prognostic test that predicts risk of distant recurrence in hormone receptor (HR)-positive, HER2-negative early breast cancer in 5 years from diagnosis. CAB has been validated extensively on retrospective cohorts from India, USA and Europe showing its comparable performance across these divergent cohorts. The current study for the first time demonstrates the recurrence risk predictions up to 10 years in a sub-cohort of a prospective clinical trial, TEAM (Tamoxifen, Exemestane Adjuvant Multinational).
Methods
CAB has been assessed on 490 Dutch patient samples enrolled in the TEAM trial from 22 centers. TEAM is a large, international clinical trial that recruited 9766 post-menopausal women, randomized for the use of hormonal therapy, sequential (2-3 years Tamoxifen + 3-2 years exemestane) or exemestane alone (5 years) and patients were followed up for at least 10 years (median=10.4, range: 0.93-15.45). The team performing CAB were blinded to clinical outcomes. The recurrence risk predictions by CAB were compared with patient outcomes by the LUMC team. The performance of CAB was estimated with Kaplan-Meier survival analysis and hazard ratios (HR).
Results
Our study cohort had 67% patients with node-positive disease, 55% had tumors greater than 2cm (T2) and 28% had poorly differentiated tumors (G3). 78% of the cohort was treated with hormonal therapy alone, either exemestane alone or sequential therapy for a period of 5 years. CAB stratified 68% of the total cohort as low risk with a DRFI (distant relapse free interval) of 86% and 32% as high risk at 10 years. In the node-positive sub-cohort, the risk proportions were 63:37 with a low risk DMFI of 88% [HR-2.84 (1.66-4.88, p<0.0001)] at 10 years and 93% at 5 years slightly higher to DMFI of post-menopausal women with RS 0-25 who participated in RxPONDER trial. The 10 year low risk DMFI was 83% (HR: 1.78, 0.9-3.3, p=0.05) in sequential and 90% in exemestane arm (HR: 3.3, 1.7-6.5, p<0.0001). Only CAB high risk patients showed a chemotherapy benefit with an improved DMFI of 14%.
Conclusions
Data from a randomised trial show the usefulness of CAB for long term (10 year) recurrence risk predictions in early stage HR-positive, HER2-negative breast cancer.
Clinical trial identification
NCT00279448, NCT00032136, and NCT00036270; Netherlands Trial Registry NTR267.
Legal entity responsible for the study
Leiden University Medical Center.
Funding
Oncostem Diagnostics, Pfizer Oncology.
Disclosure
M. Bakre: Financial Interests, Personal and Institutional, Ownership Interest: OncoStem Diagnostics Pvt Ltd. A. Gunda, B.A. Savitha, C. Prakash, P. Shrivastava, T. Kaur, M. Siraganahalli Eshwaraiah: Financial Interests, Personal, Full or part-time Employment: OncoStem Diagnostics Pvt Ltd. P. Kuppen: Financial Interests, Institutional, Research Grant, from OncoStem Diagnostics Pvt Ltd.: Leiden University Medical Center. All other authors have declared no conflicts of interest.