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The Hormone Connection: How Hormones Affect Breast Cancer

Updated on November 24, 2021
Medically Reviewed by
Dr. Dhingra
Written by
Kelly Jamrozy
2 sources cited
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Hormone imbalances affect everything from how you look to how well you sleep to your sexual performance.

In many cases, balancing your hormones improves your quality of life but doesn’t drastically affect your health. However, there is a link between hormones and some serious illnesses. This includes cancer – specifically breast cancer.

What is the link between your hormones and breast cancer?

Hormones and Breast Cancer

It’s important to understand what hormones are and what they do.

Hormones are chemical messengers. They communicate with tissues and cells and tell them what to do. Hormones travel from where the body manufactures them to their intended destination via the bloodstream.

Hormones ensure the body works as intended. They are necessary for survival. However, unbalanced hormones affect the body negatively. Too much or too little of a hormone causes illness and impacts your overall well-being.

A good example of how hormones can wreak havoc on the body is what occurs when progesterone and estrogen are unbalanced.

What Should You Know about Estrogen and Progesterone?  

These are considered female sex hormones.

They are made by the ovaries and in smaller amounts in fat and skin depending on a woman’s age. Men have estrogen and progesterone, too, but in much smaller amounts than women. 

Estrogen is responsible for the development and health of female sex characteristics.


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Progesterone plays an important role in the menstrual cycle and pregnancy. Both of these hormones play a vital role in women’s reproductive health and how they feel overall.

However, as important as estrogen and progesterone are, it’s not all good news.

These hormones are linked to the development of hormone-sensitive breast cancers.

Cells present in these types of cancers contain proteins called hormone receptors. Hormones bind to and activate these cells, which trigger changes in the expression of specific genes. This, in turn, stimulates cell growth.

Doctors determine whether or not breast cancer is hormone-sensitive by sampling tissue from the tumor to see if it contains estrogen receptors or progesterone receptors. Tumors that don’t contain these receptors can still be cancerous, but they are not hormone-sensitive types of cancer.

The vast majority of breast cancer cases are hormone-sensitive (approximately 65 to 80 percent in women and 90 percent in men).

The Hormone Connection

Recognizing the connection between hormones and breast cancer accomplishes two goals:

  1. Understanding a potential cause or something that elevates the risk of cancer helps you evaluate your risk. Knowing this risk allows you to make smarter choices about your health.
  2. Identifying the connection provides direction for developing treatments.

Several breast cancer treatment approaches utilize hormones. For example:

Blocking Ovarian Function

The ovaries are the primary source of estrogen, so suppressing or eliminating ovarian function reduces the amount of estrogen in the body.

This treatment is known as ovarian ablation. It’s also possible to suppress ovarian function temporarily with drugs that interfere with the message sent to the ovaries to start producing estrogen.

Blocking Estrogen Production

Aromatase inhibitors are drugs that block the aromatase enzyme.

This is the enzyme that makes estrogen in the ovaries and elsewhere in the body.

Blocking Estrogen’s Effects

If you don’t block the production of estrogen, you can block its effects on the body.

Several treatments achieve this, including:

  • Selective estrogen receptors modulators (SERMs)
  • Anti-estrogen drugs

Hormonal Imbalance and Cancer Risk

There is a strong link between breast cancer and hormonal imbalance.

Multiple studies, which included research from Brigham and Women’s Hospital and Harvard Medical School, determined that high levels of estrogen in the blood increased a woman’s risk of developing breast cancer.

Some researchers believe the longer exposure a woman has to estrogen throughout her life the higher her cancer risk.

For example, the studies showed that women who got their periods earlier in life and went through menopause later in life, causing longer estrogen exposure, increased cancer risk by about 3 percent for each year there is before the onset of menopause.

There is also a higher risk of developing breast cancer as women get older. The risk begins to elevate beginning in their 40s and increases each decade beyond.

Most researchers believe this is linked to the hormonal changes that occur as they age. Estrogen dominance is common during this time due to:

  • Progesterone levels decrease with age, especially if a woman undergoes a hysterectomy or other medical procedure that removes her ovaries
  • Greater difficulty making eggs as the ovaries age
  • Accumulation of environmental hormone disruptors include plastics, pollutants, and pesticides
  • Current or past use of oral contraceptives
  • Use of synthetic hormone replacement therapy
  • Unhealthy digestive tract

Estrogen dominance can trigger cell growth, putting you more at risk of developing breast cancer. This is one of the reasons why it’s so important to manage your hormonal changes and supplement when needed.

The Importance of Healthy Hormones

A healthy hormone balance is essential to good health. Having too much or too little of any hormone wreaks havoc on your body.

Keep in mind, there are phases of a person’s life when their hormones do tend to spike or drop. Puberty and pregnancy are great examples. Hormones change during this time to prepare the body for the major changes to come. In puberty, hormones spike as sexual development occurs. Hormones change during pregnancy to accommodate and support the growth of the baby.

Hormones also change as we age. It’s normal for certain hormones to drop as you age, but this doesn’t mean it feels good. If you’re experiencing hormone changes with age, speak to your doctor about how you can bring things back into balance to help you feel better.

If you aren’t over 50, nor are you going through any life-change phases, hormone imbalances could be an indication of a health problem. It’s important to speak to your doctor if you suspect problems with your hormones.

Symptoms of hormonal imbalance include:

  • Fatigue
  • Weight gain or loss
  • Decreased libido
  • Vaginal dryness
  • Hot flashes
  • Constipation
  • Cold intolerance
  • Erectile dysfunction

This is not a comprehensive list.

It’s important to work with your medical team if you feel less-than-your-best. Sometimes the problem is a mix of hormonal imbalance and other causes or it’s a cycle and one thing is affecting another.

The important thing to remember is to not ignore how your body feels because in many cases, the fix is simple. And in other cases, hormonal issues put you at risk of developing serious diseases. 

Ways to Manage Hormones

There are many things you can do to reduce your risk of cancer.

These things don’t guarantee you won’t develop cancer. However, regardless of your existing risk, these lifestyle changes reduce the odds of a cancer diagnosis. 

First and foremost, do your best to live a healthy life that includes plenty of nutritious food and exercise. Avoid tobacco and address any chronic problems, even if they seem minor.

Speak to your doctor about what supplements you can add to your diet to improve your overall health.

In addition to lifestyle changes, a saliva hormone test helps you determine if you’re suffering from an imbalance.

If a test shows you have too much or too little estrogen or progesterone, you should speak to your doctor about bringing things into balance.

Hormone supplementation is a safe and effective way to manage your hormone balance and reduce your risk of developing illnesses and diseases related to hormones.


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“Hormone Therapy for Breast Cancer.” National Cancer Institute,, 2011,

“Hormone Mix Raises Breast Cancer Risk.” Harvard Gazette, 24 July 2006,

Dr. Dhingra
Dr. Harshi Dhingra
Medical Reviewer
Dr Harshi Dhingra is a licensed medical doctor with a specialization in Pathology. Dr. Dhingra has of over a decade in diagnostic, clinical, research and teaching work, including managing all sections of Pathology laboratory including histopathology, cytology, hematology and clinical Pathology.
Kelly Jamrozy
Content Contributor
Kelly has experience working with clients in a variety of industries, including legal, medical, marketing, and travel. Her goal is to share important information that people can use to make decisions about their health and the health of their loved ones. From choosing the best treatment programs to improving dental and vision health to finding the best method for helping anyone who is struggling with health issues, she hopes to share what she learns through informative content.
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