Estrogen, Progesterone, and the BRCA12 Gene

Estrogen and progesterone are essential hormones in the human body, playing critical roles in various physiological processes. These hormones are particularly significant in the context of reproductive health, but they also have implications for other aspects of overall wellbeing. Additionally, there is a noteworthy connection between these hormones and the BRCA1 and BRCA2 genes, which are associated with an increased risk of breast and ovarian cancers. In this article, we explore the roles of estrogen and progesterone, their impact on breast and ovarian cancer risk, and the interaction with the BRCA1 and BRCA2 genes.

The Roles of Estrogen and Progesterone


  • Estrogen is a group of hormones primarily produced by the ovaries and, to a lesser extent, by the testes.
  • It plays a pivotal role in the development of secondary sexual characteristics, including breast development and regulation of the menstrual cycle.
  • Estrogen also influences bone health, cardiovascular health, and mood.


  • Progesterone is another hormone produced primarily by the ovaries, specifically during the second half of the menstrual cycle.
  • It prepares the uterine lining for potential pregnancy and helps maintain pregnancy if it occurs.
  • Progesterone is involved in regulating the menstrual cycle and contributes to mood stability.

Breast and Ovarian Cancer Risk

BRCA1 and BRCA2 Genes:

  • The BRCA1 and BRCA2 genes are tumor suppressor genes responsible for repairing damaged DNA and preventing the formation of cancerous cells.
  • Mutations in these genes can lead to a significantly increased risk of breast and ovarian cancers, among others.

Estrogen, Progesterone, and Cancer Risk:

  • Estrogen can stimulate the growth of breast and ovarian tissues, which is why it is considered a risk factor for these cancers.
  • Progesterone can counterbalance the effects of estrogen by inhibiting cell growth and promoting cell differentiation, potentially reducing the risk of certain hormone-sensitive cancers.

Interaction Between Hormones and BRCA1/2 Mutations

  • Women with BRCA1 or BRCA2 mutations have an elevated risk of developing breast and ovarian cancers.
  • Estrogen replacement therapy in women with these mutations has raised concerns about potentially increasing cancer risk.
  • The interaction between hormone therapy and BRCA1/2 mutations is complex and requires careful consideration.

Implications and Considerations

  • Individualised Approach: It’s essential to take an individualised approach when considering hormone therapy for individuals with BRCA1 or BRCA2 mutations. The decision should involve discussions with sources that are knowledgeable about cancer risk and hormone therapy.
  • Surveillance and Monitoring: People with BRCA1 or BRCA2 mutations may undergo increased surveillance, including regular mammograms, breast MRI, and ovarian ultrasounds to detect cancers at an early, more treatable stage.
  • Risk Reduction Strategies: In some cases, risk-reducing surgeries such as prophylactic mastectomy or oophorectomy (removal of the ovaries) may be considered to reduce cancer risk. In these cases, it would be unwise to promote breast development with gender-affirming hormones if the risk is considered to the this high.
  • Lifestyle Factors: Lifestyle factors, such as maintaining a healthy weight, regular exercise, and a balanced diet, can also influence cancer risk and overall health.


Estrogen and progesterone are critical hormones with multifaceted roles in the human body, including the regulation of the reproductive cycle, secondary sexual characteristics, and overall health. In individuals with BRCA1 or BRCA2 mutations, the interaction between hormone therapy and cancer risk is a complex consideration that requires careful evaluation and a personalised approach. Regular surveillance and discussions with healthcare providers are essential for managing cancer risk in these individuals if they have breast tissue or ovaries. Overall, a well-informed and holistic approach to health and wellness is essential for everyone, taking into account individual factors and genetic predispositions.

Updated on January 12, 2024

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