Using an LHRH agonist with or without tamoxifen after breast cancer surgery may be an alternative option for premenopausal women with estrogen receptor-positive early stage breast cancer to reduce their risk for recurrence, results of a recent report indicate.
Researchers collected data from 14 clinical trials involving the use of LHRH (luteinizing hormone-releasing hormone) agonists, medicines that control the release of estrogen by suppressing ovarian function indirectly. They concluded that LHRH agonists may help reduce the risk of recurrence and death from breast cancer.
Study Background and Goals
Women with estrogen receptor-positive (ER+) breast cancers, or cancers that are stimulated by the hormone estrogen, benefit from therapies that interfere with estrogen’s ability to interact with cancer cells. Tamoxifen, the standard hormonal therapy for premenopausal women, blocks the estrogen receptors on cancer cells, preventing estrogen from fueling a tumor.
Premenopausal women may get additional benefits from medicines that stop the ovaries from producing estrogen. LHRH agonists, such as goserelin (brand name: Zoladex) and leuprolide (brand name: Lupron), indirectly suppress the ovaries’ ability to produce estrogen by interfering with the release of stimulating hormones.
The researchers in this study wanted to assess the potential effectiveness of incorporating LHRH agonists into a treatment regimen that may also include tamoxifen, chemotherapy or both.
The data for the trials included in this study came from trial reports selected by careful review of the registry of the Cochrane Breast Cancer Group, an international network that centralizes data from clinical trials around the world to help researchers make well-informed recommendations about health care. The individual trials had different goals and structures, but all randomly assigned premenopausal women with ER+ early stage breast cancer to take one of the following combinations:
- LHRH agonist versus LHRH agonist plus tamoxifen
- LHRH agonist versus chemotherapy
- LHRH agonist versus ovarian ablation
- LHRH agonist versus LHRH agonist plus chemotherapy
The researchers compared how each treatment affected survival time without breast cancer recurrence (recurrence-free survival), time lived after a diagnosis of breast cancer (overall survival), side effects, and quality of life. Most trials used goserelin as the LHRH agonist. Nearly 12,000 women, most with ER+ breast cancer but some with ER unknown breast cancer, contributed data to the analysis.
Comparisons of an LHRH agonist containing regimen against the current standards of care (tamoxifen alone or chemotherapy plus tamoxifen) were underrepresented or not represented because of limited or nonexistent data. Researchers are working to gather this data through ongoing clinical trials.
Overall, the researchers found a suggestion of added treatment benefit with an LHRH agonist with or without tamoxifen in the absence of chemotherapy. Comparisons related to an LHRH agonist with or without tamoxifen and chemotherapy did not demonstrate any significant differences in recurrence-free survival or overall survival. The authors concluded that hormonal therapy was associated with fewer side effects than the CMF-based chemotherapy regimens included in the review.
The researchers stated that there is a need for additional research to determine the most effective means of incorporating LHRH agonists into the postsurgical care of premenopausal women with ER+ or ER-unknown early stage breast cancer.
What Does This Study Mean for Me?
If you are a premenopausal woman who has been diagnosed with ER+ early stage breast cancer, adding an LHRH agonist to tamoxifen therapy may be one option for you to discuss with your doctor. Clinical trials are ongoing that involve the use of LHRH agonists in which you can participate.
R. Sharma, et al. LHRH agonists for adjuvant therapy of early breast cancer in premenopausal women. Cochrane Database Syst Rev. 2008 Oct 8; (4): CD004562