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Tamoxifen in Breast Cancer Treatment and Estrogen for perimenopausal and menopausal symptoms.

Updated: 4 days ago



Breast cancer treatment often involves a delicate balance of therapies tailored to each patient’s specific needs. Among the pivotal medications used is tamoxifen, a Selective Estrogen Receptor Modulator (SERM) renowned for its intricate interaction with estrogen—a hormone intricately linked to breast cancer biology.


Understanding Tamoxifen: Blocking and Mimicking Estrogen


Tamoxifen’s role as a SERM means it possesses dual capabilities in breast tissue. On one hand, it acts as an estrogen blocker, competing with natural estrogen for binding sites on estrogen receptors within breast cells. This blockade is crucial in estrogen receptor-positive breast cancers, where estrogen fuels tumor growth. On the other hand, tamoxifen can also mimic estrogen’s effects under certain conditions, particularly in bones and the cardiovascular system, where it supports bone density and cardiovascular health.


The Paradox of Estrogen: Growth Stimulant and Cell Regulator


Estrogen’s relationship with breast cancer is paradoxical. While it can stimulate growth in estrogen receptor-positive breast cancer cells, there’s evidence suggesting that prolonged deprivation of estrogen—such as through menopause or therapy—can induce apoptosis, or programmed cell death, thereby potentially reducing the risk of breast cancer recurrence. However, the exact duration of estrogen deprivation required to trigger this protective effect remains a subject of ongoing research.


Tamoxifen and Hormone Replacement Therapy (HRT): Uncertainties and Considerations


One of the complexities in breast cancer management lies in the intersection of tamoxifen with hormone replacement therapy (HRT). While tamoxifen blocks estrogen receptors in breast tissue to prevent cancer recurrence, the concomitant use of HRT introduces estrogen back into the system. This juxtaposition raises critical questions about the safety and efficacy of combining these therapies. Current evidence regarding whether breast cancer outcomes are improved with the addition of HRT alongside tamoxifen or whether HRT should be avoided altogether remains inconclusive and varies based on individual patient characteristics and cancer subtype.


Looking Forward: Investigating Complex Interactions


Given the intricacies outlined, ongoing research efforts are focused on elucidating these interactions between tamoxifen, estrogen, and HRT. Various clinical trials and studies are exploring optimal treatment regimens that maximize therapeutic benefits while minimizing potential risks for breast cancer patients. Moreover, collaborative initiatives involving oncologists, breast surgeons, patients, radiologists, and researchers are essential in addressing these real-world clinical conundrums.


In conclusion, the management of breast cancer with tamoxifen and considerations of estrogen’s role reflect the evolving landscape of personalized medicine. As research advances and new insights emerge, healthcare providers continue to refine treatment strategies to offer the best possible outcomes for patients navigating the complexities of breast cancer treatment.


Adjuvant tamoxifen therapy for about 5 years link

reduces breast cancer mortality by 31% for estrogen receptor-positive tumors, regardless of age or chemotherapy use, with cumulative benefits increasing substantially over 15 years post-diagnosis. These findings underscore the enduring efficacy of these treatments in reducing long-term breast cancer mortality rates, though potential for further improvements with newer therapies is acknowledged.


1. Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials. Lancet. 2005 May 14-20;365(9472):1687-717. doi: 10.1016/S0140-6736(05)66544-0.

2. Jordan VC. Tamoxifen: a most unlikely pioneering medicine. Nat Rev Drug Discov. 2003 Jan;2(3):205-13. doi: 10.1038/nrd1031.

3. Clemons M, Goss P. Estrogen and the risk of breast cancer. N Engl J Med. 2001 Feb 15;344(4):276-85. doi: 10.1056/NEJM200102013440507..



By dr Purity Carr

GP & Menopause Doctor

Harvey, WA


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