The Role of Progesterone Receptors in Breast Cancer

Jeannette | Posted on April 20, 2023 
progesterone and breast cancer

Progesterone and breast cancer share a common link. The mammary glands’ proper growth and function require progesterone. The hormone function is receptor-dependent. The progesterone receptor (PR) is a receptor that regulates gene expression. The receptor controls the hormone (progesterone) action. Coregulators can modify the PR’s function. Consequently, a mutation or abnormal coregulator expression may affect the PR’s normal function. This may also affect the normal development of the mammary gland, resulting in breast cancer.

Today’s post is about progesterone and breast cancer, as it sheds light on the important role that PR plays in breast cancer. The article also discusses the role of progesterone in breast cancer. So, continue reading to find the link between breast cancer and progesterone.

Progesterone and Breast Cancer

Hormone estrogen and progesterone can regulate the growth and development of human tissues with the aid of estrogen and progesterone receptors. This includes the reproductive system and the breasts. These receptors are also crucial indicators of the health effects of breast cancer and other reproductive system tumors.

Receptors are proteins that can attach to specific molecules. They are found within and on cells. Estrogen and progesterone receptors are present in normal and some breast cancer cells. Without hormones, cells could not grow; hence, they require these receptors.

Association of the Receptor with Progesterone and Breast Cancer

PR is a crucial steroid hormone receptor that contributes to the formation and progression of breast cancer as well as to the healthy development of the mammary gland. Moreover, PR is a biomarker widely utilized to characterize breast cancer during the diagnostic phase. PR is essential for molecular subtyping and identifying the optimal course of treatment.

The link between breast cancer and progesterone is evident from the presence and absence of receptors. Based on receptors’ presence or absence, cancer cells are categorized as:

  • ER-positive (ER+): Breast cancers with estrogen receptors
  • PR-positive (PR+): Breast cancers with progesterone receptors
  • Hormone-receptive-positive (HR+): The cancer cell possesses two receptors
  • Hormone-negative (HR-): Cancer that lacks estrogen or progesterone receptors

The growth and spread of the tumor are inhibited by preventing estrogen and progesterone from attaching to their respective receptors. Numerous medications can be utilized for this purpose.

Role of Progesterone in Breast Cancer

It is important to discuss estrogen’s role better to understand the role of progesterone in breast cancer. Both hormones work in tandem in the development and progression of breast cancer.

Estrogen encourages the formation of malignant cells, but progesterone tricks the immune system into believing it has been defeated. The immune system finds and kills microscopic tumors in our bodies, thereby preventing cancer development. Progesterone, on the other hand, makes it more difficult to detect tumor cells. Breast cancer and progesterone are strongly related.

If circulating breast tumor cells are exposed to progesterone, the hormone obscures the immune-recognizable warning signals that a breast tumor emits. Breast cancer may grow more aggressive if this occurs. Progesterone adds to tumor cells’ capacity to remain unnoticed.

hormonal replacement therapy

If cancer cells continue to send their signal, our immune system may become overstimulated. As a result, the ability of the immune system to remove cancer cells may be compromised. Immune checkpoint inhibitors strengthen patients’ immune systems and enhance their capacity to combat tumor cell growth. Certain tumors, like skin cancer and lung cancer, are more likely than others to respond to immunotherapy with immune checkpoint inhibitors. On the other hand, breast cancer does not respond well to this sort of treatment because they are immunologically cold (does not stimulate the immune system much).

Progesterone and breast cancer are associated in a manner that the hormone inhibits the immune system’s ability to function. As a result, breast tumors are immunologically cold. Anti-progesterone may enhance the efficacy of immune checkpoint inhibitors in treating breast cancer.

Knowing the Receptor Status for Progesterone and Breast Cancer

The association between progesterone and breast cancer is linked with the treatment options. Cancer can be treated more effectively if doctors understand the disease’s hormone receptor status better. Whether or not the patient’s tumor contains one or both of these receptors, hormone therapy can reduce the body’s estrogen level or prevent it from functioning normally on breast cancer cells. This technique is beneficial for breast cancer patients with positive hormone receptors but useless for those with negative hormone receptor tumors (ER- and PR-negative).

Testing for these hormone receptors must be performed on a tissue sample acquired during a biopsy or when the tumor is surgically removed for any invasive breast cancer.

Immunohistochemistry (IHC) is the most prevalent method for determining if cancer cells contain estrogen and progesterone receptors. The test results help determine the optimal course of action for your circumstance.

The test results indicate the condition of the hormone receptors.

Hormone receptor-positive: Breast cancer cells have progesterone receptors (PR), estrogen receptors (ER), or both. These cancers are treatable with hormone therapy that inhibits or reduces the body’s estrogen receptors. Tumors with positive hormone receptors often progress more slowly than cancers with negative receptors.

Hormone receptor-negative: Breast cancers are devoid of estrogen or progesterone receptor expression. These malignancies are not treatable with hormone treatment medicines. These tumors grow quicker than those having hormone receptors on their cells.

Triple-negative: Cancer cells do not have estrogen, progesterone, and HER2 receptors. These malignancies are more prevalent in women under 40. These tumors grow and spread more rapidly than most other subtypes. Since cancer cells lack hormone receptors, hormone therapy is ineffective in treating them. In addition, medications targeting HER2 are ineffective against these cancers because they do not contain a significant quantity of HER2. In some instances, chemotherapy may still be beneficial.

Triple-positive: There are positive results for all three biomarkers (ER, PR, and HER2). These tumors may be effectively treated with hormone treatment and HER2-targeting medications.

Breast cancer’s onset and spread are significantly influenced by progesterone receptors (PR). Breast cancer cells with PRs have a better prognosis and respond better to hormone therapy. By using functional PRs, hormone therapy prevents estrogen from having an impact on breast cancer cells. Contrarily, breast tumors without functional PRs are more aggressive and less sensitive to hormone therapy. It is critical to comprehend the role of receptors and progesterone in breast cancer to forecast disease progression and direct treatment choices.

See Also: What Are The Benefits Of Progesterone After Menopause?


Progesterone contributes to the growth and development of tumors in breast cancer. Certain breast cancer cells with functioning progesterone receptors can develop when progesterone levels are high. Estrogen-blocking or progesterone-production-suppressing hormone therapy is used to treat breast cancer. Estrogen can promote the growth of some breast tumors. The existence and function of PRs in breast cancer cells determine how well hormone treatment works. Progesterone’s effect on breast cancer is complex and dependent on the existence and functionality of PRs and other hormones. Progesterone can both promote and hinder the proliferation of breast cancer cells.

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