ER, PR, HR—hormones and breast cancer

HR positive or negative, PR positive or negative, ER positive or negative—these are the various types of hormone status in breast cancer.

  • HR is the acronym for hormone receptor
  • ER = estrogen receptor
  • PR = progesterone receptor

This information is important because it influences treatment options and an individual’s prognosis.

About female hormones

Estrogen and progesterone are often called the female hormones because of the role they play in a woman’s menstrual cycle, sexual development, and pregnancy. These hormones diminish after menopause but continue to be present in post-menopausal women.

Female hormone wannabe’s

Along with the estrogen naturally produced in our bodies, we are exposed to xenoestrogens, which are synthetic or natural substances that imitate estrogen.

  • Synthetic xenoestrogens include chemicals like BPA and phthalates that are widely used in packaging and other products but best avoided.
  • Natural xenoestrogens include plant-derived phytoestrogens found in nuts and seeds, fruits, vegetables, legumes and herbs—soy is one of the better known phytoestrogens. Xenoestrogens can be risky for people with HR+ breast cancer, which is why some oncologists advise their patients to avoid them completely.

While known as female hormones, men also produce estrogen and progesterone but in smaller amounts, just as women produce testosterone in smaller amounts. Since men have breasts and some estrogen and progesterone, they also can develop breast cancer, although it’s not common.

According to the American Cancer Society, about 2,620 new cases of invasive breast cancer will be diagnosed in men and over 500 of them will die from breast cancer in the United States.

A special shout-out to any man with breast cancer—or anyone who knows a man with breast cancer—as I’m sure that minority status in the predominantly female breast cancer community comes with its own unique burdens and challenges. Blessings and love to all my brothers—and sisters—in the bc tribe.

About hormone receptors

Estrogen and progesterone receptors are proteins on the surface of breast cells that help control the way breast cells grow. These proteins are often described as:

  • The receptors are the “lock”
  • Hormones are the “key” that can open the lock

HR Positive

Sometimes too many receptors are produced, or in medical parlance, they are over-expressed. Over-expression is a problem because things can quickly get out of control when estrogen and progesterone attach to these hormone receptors and fuel cancer growth. Over-production also can happen with another factor that drives breast cancer—HER2 or human epidermal growth factor receptor 2.

About 70% of breast cancers are hormone receptor-positive and may receive signals from estrogen that could promote their growth.

HR Negative

Breast cancers that are HR- have few or no receptors.

HR-negative breast cancers tend to have worse five-year survival rates than HR-positive cancers—about 10%, although that difference begins to decrease with time.

Triple-negative breast cancer

Triple-negative breast cancer (tnbc) has neither estrogen or progesterone receptors and also doesn’t over-produce the HER2 protein. Triple-negative is the least common form of breast cancer—only 10 to 20 percent at the time of diagnosis and only 1 percent of male diagnoses.  When tnbc does occur, it tends to be in women under 40 years of age, in African-American women, and in those who have the BRCA 1 gene mutation.

Triple-negative breast cancers grow and spread faster than most other types of breast cancer. Because the cancer cells don’t have hormone receptors, hormone therapy is not helpful. Since HER2 is not over-expressed, drugs that target HER2 aren’t helpful either.

People who get tnbc must experience a special kind of heartbreak when they hear the news. If that includes you, you have my virtual love and support. I encourage you to learn as much as you can, work in close partnership and collaboration with all your caregivers, keep the faith because new treatment options are being discovered, and most importantly, live every day with purpose, gratitude, and as much joy as you can find and create.

Lab-testing differences and status changes

Labs have different cutoff points for identifying cancer as hormone receptor positive or negative, which means in some marginal cases, one lab could determine a positive status while another calls it negative and a third lab labels it unknown. Since studies have shown that even cancers with low hormone receptors can respond to hormonal therapy, this difference could make a difference.

The American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) are concerned about quality-control and working to develop consistent standards to reduce lab variabilities and establish a threshold for ER positive designation. In questionable cases, they also suggest additional steps like a second reviewer and testing a different block of cells.

Similar to HER2 status, some breast cancers can change their hormone receptor status over time from positive to negative or vice versa.

Putting it all together

You rarely hear about hormone receptor status on its own; it’s always mentioned along with human epidermal growth factor receptor 2 or HER2 status.

  • HR+, HER2- is the most common, found in about 73 percent of all people with metastatic breast cancer, including me.
  • HR-, HER2+ is the least common, at only 4 percent.
  • HR-, HER2- is the profile of 12 percent of diagnoses.
  • HR+, HER2+ happens in about 11 percent of diagnoses.

Breast cancer researchers have learned a lot about the disease and what causes it. Hormone receptors play a major role, along with HER2 receptors.

Causes of cancer beyond hormones

Additional contributing factors include cancer-related genes, certain enzymes produced by cancer cells that help them spread, inherited genetic mutations and to a more mysterious degree, living environment and lifestyle. Mysterious because they can contribute to breast cancer, but not always with a direct, solid link.

For example, people who are overweight are at greater risk, yet many thin people get cancer, myself included. I have been thin (thanks in part to my 5’11” long frame) and my weight and BMI (body mass index) have been pretty stable my entire adult life. My diet is largely healthy—certainly healthier than the average American diet of high meat and dairy, high fat and sugar, and low consumption of whole foods.

All that aside, the understanding of how cancer develops and spreads is a remarkable opus of knowledge gained over many decades of trial and error discovery. That knowledge is making more treatment options available to target and attack the specific signals that drive the growth of any cancer in a given patient.

Click here to read my HER2 explanation