In a nutshell
The study evaluated whether Breast Cancer Index (BCI) can predict benefits from extended endocrine therapy (EET) in patients with hormone-receptor-positive (HR+) early-stage breast cancer (BC). The authors found that BCI can predict which patients would benefit from 10 years of EET.
Endocrine therapy (ET) prevents tumor growth in patients with HR+ BC. They normally receive 5-years of adjuvant-ET, which is given to maximize the effects of a primary treatment. Extending such ET to a total of 10-years reduces relapse but causes severe toxicities. It is important to select patients for EET by balancing toxicities versus benefits.
BCI is a genetic test that previously predicted risks of relapse in HR+ BC. Its power to predict benefits from EET is unknown.
Methods & findings
The study conducted the BCI test on tumor samples of 908 adult women with early-stage HR+ BC. After completing 5 years of adjuvant-ET, half of the patients received 2.5-years of ET with letrozole (Femara). The other half received 5-years of letrozole (EET group).
47% of patients had high BCI-scores. In these patients, the BCI test predicted 58% higher chances of benefitting from letrozole treatment another 5 years. Risks of relapse were 5.9% for the EET group and 15.7% for patients who received 2.5 years of letrozole. Patients in the EET group had a 9.8% lower risk of recurrence compared to those in the 2.5-year group.
A total of 53% of patients had low BCI scores. Among these patients, the duration of letrozole therapy had no impact on the benefit and risks of relapse. The risk of recurrence was 14.9% with EET and 15.4% in the 2.5-year therapy group.
In patients receiving an aromatase inhibitor (AI) such as letrozole as part of adjuvant-ET, high BCI scores predicted significant benefits from EET. 5-years of letrozole had a 66% higher benefit compared to 2.5-years.
Among patients with high-risk disease (HRD) and cancer spreading to lymph nodes, 46% had high BCI-scores. 5-years of letrozole had 68% higher chances of a benefit than 2.5-years.
The bottom line
The study concluded that high BCI scores can predict benefit from 5 versus 2.5 years of letrozole therapy in patients with early-stage HR+ BC.
The fine print
This study was based on medical records. Many of the patients were also receiving chemotherapy. This might have influenced the results.
Published By :
Clinical Cancer Research
Oct 27, 2020
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