Endocrine Therapy Provides 20-Year Benefit in ER+ Breast Cancer

Two years of adjuvant endocrine therapy in premenopausal patients with estrogen receptor-positive (ER+) breast cancer can reduce the risk of recurrence at 20 years, according to a study published in the Journal of Clinical Oncology.  

Researchers observed significant improvements in long-term distant recurrence-free interval (DRFI) for patients who received goserelin alone, tamoxifen alone, or the combination of goserelin and tamoxifen, when compared with patients who did not receive endocrine therapy. 

However, combination goserelin and tamoxifen did not improve DRFI when compared with either agent alone.

Researchers assessed the 20-year benefit of endocrine therapy by analyzing data from the Stockholm trial (1990-1997). The analysis included 584 patients with ER+ breast cancer. The median age at baseline was 47 (range, 26-55) years, 91% of patients had progesterone receptor-positive tumors, and 88% had HER2-negative tumors.

Patients were randomly assigned to 2 years of goserelin (n=155), tamoxifen (n=135), combined goserelin and tamoxifen (n=149), or no adjuvant endocrine therapy (n=145).

Patients were stratified according to lymph node status. Lymph node-positive patients received standard chemotherapy (cyclophosphamide, methotrexate, and fluorouracil), and patients with 4 or more positive lymph nodes received locoregional radiotherapy.

In a multivariable analysis, any endocrine therapy was associated with a significant improvement in long-term DRFI, when compared with no endocrine therapy. 

There was a significant improvement in DRFI with goserelin alone (hazard ratio [HR], 0.49; 95% CI, 0.32-0.75), tamoxifen alone (HR, 0.57; 95% CI, 0.38-0.87), and goserelin plus tamoxifen (HR, 0.63; 95% CI, 0.42-0.94). 

However, there was no significant long-term benefit from the combination of goserelin plus tamoxifen, when compared with either agent alone. There was a significant interaction between goserelin and tamoxifen (P =.016). 

The researchers also assessed the long-term benefit of endocrine therapy in patients with low genomic risk (n=305) and those with high genomic risk (n=158). 

Patients with low-risk genomics had a significant improvement in DRFI with tamoxifen (HR, 0.24; 95% CI, 0.10-0.60), and patients with high-risk genomics had a significant improvement in DRFI with goserelin (HR, 0.24; 95% CI, 0.10-0.54).

Patients with high-risk genomics had significantly worse DRFI when tamoxifen was added to goserelin (HR, 3.36; 95% CI, 1.39-8.07). The interaction between goserelin and tamoxifen was significant in high-risk patients (P =.006) but not in low-risk patients (P =.080). 

“This study demonstrates long-term benefit from 2 years of adjuvant endocrine therapy in ER-positive premenopausal patients,” the researchers concluded. “Furthermore, it suggests long-lasting benefit from tamoxifen in genomic low-risk patients with long-term risk of distant recurrence, whereas genomic high-risk patients have early risk and benefit from goserelin.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.  

Reference

Johansson A, Dar H, van ‘t Veer LJ, et al. Twenty-year benefit from adjuvant goserelin and tamoxifen in premenopausal patients with breast cancer in a controlled randomized clinical trial. J Clin Oncol. Published online July 21, 2022. doi:10.1200/JCO.21.02844

This article originally appeared on Cancer Therapy Advisor