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Understanding Hormone Therapy for Breast Cancer: A Comprehensive Guide

by Dr. Charles Weaver, Medical Advisor.


Hormones play a vital role in the female body, and estrogen is one of the most crucial. It’s responsible for various functions, including the development of female sex organs, pregnancy preparation, and maintaining cardiovascular and bone health. However, estrogen can also contribute to the growth of certain cancers, particularly estrogen receptor-positive (ER+ positive) breast cancers. This article explores the complex relationship between estrogen and breast cancer and delves into the various treatments available to manage this type of cancer.

Estrogen’s Dual Role

Estrogen’s importance in the female body is undeniable, but it can also be a double-edged sword. While essential for various bodily functions, estrogen can cause some cancers to grow, particularly those with estrogen receptors. These are known as ER+ positive cancers, and managing the exposure to estrogen is a key goal in treating them.

Hormonal Therapy for Breast Cancer

Hormonal therapy aims to reduce or slow the growth of ER+ positive breast cancer cells by minimizing exposure to estrogen. However, this reduction can lead to side effects, as estrogen is necessary for bone growth and cardiovascular health. Various drugs have been developed to achieve this goal, including aromatase inhibitors (AI) and Faslodex (fulvestrant), which have replaced older drugs like Tamoxifen.

How Hormonal Therapy Works

Hormonal therapy works by decreasing estrogen’s effect on cancer cells. This can be done by:

  • Removing the ovaries in premenopausal women.
  • Inhibiting the conversion of androgens to estrogens.
  • Blocking estrogen receptors.

These methods aim to control the growth of cancer cells by manipulating estrogen levels.

Types of Anti-Estrogen Drugs

Three main classes of drugs are used to decrease estrogen’s effects:

  1. Aromatase Inhibitors: These block the conversion of androgens to estrogen, particularly in postmenopausal women. Examples include Femara® (letrozole), Arimidex® (anastrozole), and Aromasin® (exemestane).
  2. Selective Estrogen Receptor Modulators (SERMs): These block estrogen receptors within breast cells. Tamoxifen is the most common SERM used.
  3. Estrogen Receptor Antagonists: These prevent estrogen from stimulating the growth of estrogen receptor-positive cells. Faslodex® is a known antagonist.

Combination Therapy

Combination therapy involves using precision cancer medicines like cyclin-dependent kinases (CDK) inhibitors with anti-estrogen drugs. This approach has been found to delay cancer progression and prolong survival. Drugs like Verzenio (abemaciclib), Kisqali (ribociclib), and Ibrance (palbociclib) are commonly used in combination therapy.

Hormonal Therapy in Early-Stage and Metastatic Breast Cancer

Hormonal therapy benefits women with hormone receptor-positive early-stage breast cancer by reducing the risk of recurrence. For metastatic or recurrent breast cancer, hormonal therapy can be a vital part of the treatment strategy. The use of genomic assays like the Breast Cancer Index can further personalize treatment plans.

Genomic Assays and Treatment Decision Making

Genomic testing can provide insights into an individual’s cancer and guide treatment decisions. The Breast Cancer Index test is one such tool that helps predict recurrence risk and the potential benefit of extending hormonal therapy.

Side Effects of Endocrine Therapy

Endocrine therapy can lead to side effects similar to menopause symptoms, such as hot flashes and irregular menstrual periods. More serious side effects can include blood clots, cataracts, and uterine cancer. Understanding these side effects is essential for managing them effectively.

Hormonal Therapy for Breast Cancer Prevention

Drugs like tamoxifen and Evista® (raloxifene) have been shown to reduce the risk of breast cancer in high-risk women. These drugs block the effects of estrogen and are approved for breast cancer risk reduction.


Hormonal therapy for breast cancer is a complex and multifaceted treatment approach. Understanding the various options, their mechanisms, benefits, and potential side effects is crucial for patients and healthcare providers to make informed decisions. As always, open communication with healthcare professionals is key to finding the best treatment path.

For full article: Cancerconnect – Endocrine – Hormone Therapy For Breast Cancer

Copyright breastcancerconnect 2023.

In the journey of understanding and treating hormone receptor-positive breast cancers, education and awareness are key. This is where initiatives like Learn Look Locate play a vital role. Learn Look Locate encourages individuals to learn about their bodies, look for changes, and locate resources and medical assistance if needed. With a focus on early detection and empowerment, it aligns with the principles of understanding complex treatments like hormone therapy. By embracing the Learn Look Locate method, patients and caregivers can take an active role in their health, making informed decisions about treatments like those discussed above, and ensuring the best possible outcomes.