Abstract 182P
Background
There are arguments about the cost-effectiveness of the multi-gene testing for chemotherapy decision-making in the low-risk luminal breast cancer. This study aims to explore new clinical low-risk criteria that could spare patients from multi-gene testing if these patients have a 5-year distant metastatic rate of less than 3% and 5-year any recurrence rate of less than 5%.
Methods
Breast cancer patients initially treated with primary surgeries between 1990 and 2010, who met the following criteria, (1) pathologic node-negative, (2) hormone receptor-positive, and (3) HER2-negative, were enrolled in this study. Out of the total 1595 eligible patients, 886 (55.5%) patients received adjuvant chemotherapy in addition to endocrine therapy. Two clinical low-risk criteria were used to define the low-risk patients: (1) age > 35 years and (grade 1 with tumor ≤3cm, grade 2 with tumor ≤2cm, or grade 3 with tumor ≤1cm) (the control criteria), and (2) age > 40 years, grade 1-2, and tumor ≤ 1.5cm (the new criteria). Kaplan-Meier statistics estimated the difference between outcomes in low- and high-risk groups.
Results
There were statistical significances of 5-year distant metastases-free survival (DMFS) and 5-year recurrence-free survival (RFS) between low-risk and high-risk groups (P < 0.0001) by both criteria; low-risk patients defined by the control and new criteria without adjuvant chemotherapy had a 5-year DMFS of 97.9% vs. 99.1% and 5-year RFS of 96.5% vs. 97.5%, respectively. Using current new criteria, the distant metastatic rates at 5 years for patients with and without chemotherapy were 0.8 and 0.9%, respectively. The estimated recurrence events of low-risk patients were halved by the new criteria as compared with the control criteria.
Conclusions
The benefit of chemotherapy in low-risk patients might be very small by the new criteria since the overall distant metastatic rate is less than 1% within 5 years. We assumed that multi-gene testing in those patients would not be cost-effective.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Hung-Chun Skye Cheng.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.