What is Estrogen Receptor-Positive Breast Cancer?
Estrogen is the female sex hormone responsible for the growth, development, and regulation of the female reproductive system and secondary sex organs.
The cells that respond to this hormone contain proteins that bind to it and bring about the required effect. These proteins are known as estrogen receptors and are found in female reproductive tissues and cancer cells.
Breast cancers that grow in response to estrogen due to the presence of estrogen receptors are known as estrogen receptor-positive or ER-positive breast cancer.
These cancers grow slower than ER-negative cancers and account for 80% of all breast cancers.
They also have better treatment outcomes in the short term but tend to relapse after years of treatment.
Testing For Hormone Receptors In Breast Cancer
In ER-positive cancers, the growth of cancer cells is estrogen-dependent.
So, hormone therapy drugs can be used to lower estrogen levels in the body or prevent estrogen from affecting breast cancer cells.
Knowing the hormone receptor status of breast cancers can help doctors figure out the ideal treatment plan for the patient.
Risk For Er Positive Cancers: Genetic Factors
The BRCA Genes
Women who are carriers of the BRCA1 gene mutations are more likely to develop ER-positive breast cancer as they age.
10-36% of breast cancer cases in people with BRCA1 gene mutations are ER-positive breast cancers.
According to a study, most women with BRCA2 mutations develop ER-positive breast cancer and the treatment outcome for these women may be poorer than BRCA2 carriers having ER-negative breast cancer.
The CYP19A1 Gene
Estrogen exposure plays a significant role in breast cancer. The CYP19A1 or Cytochrome P-450, family 19, subfamily A, contains instructions for the production of aromatase, an enzyme that regulates the final step in the production of estrogen in the body.
Abnormal changes in the CYP19A1 gene are significantly associated with different levels of circulating estrogens
Treatment with Aromatase inhibitor drugs that suppress estrogen production yield better outcomes in ER-positive breast cancer patients with mutations in their CYP19A1 gene.
The ESR1 Gene
The ESR1 gene contains instructions for the production of estrogen receptor alpha (a type of estrogen receptor).
Certain changes in the ESR1 gene increase the resistance of cancer cells to hormonal therapy, the standard treatment plan for ER-positive cancers.
Non-genetic Factors
- Age: Older women tend to have a higher amount of estrogen receptors, increasing their risk for ER-positive breast cancer.
- Lifetime exposure to estrogen: Women who begin menstruating early, attain menopause late, or do not have children are at a higher risk of ER-positive breast cancer due to longer lifetime exposure to estrogen.
- Alcohol consumption: Alcohol can increase the levels of estrogen and other hormones associated with ER-positive breast cancer. It increases the likelihood of developing ER-positive breast cancer.
- Hormone treatment post-menopause: Women who take hormone therapy after menopause are more likely to develop ER-positive breast cancer.
- Higher BMI (Body Mass Index): Obesity amplifies the risk for ER-positive breast cancer because adipose tissue acts as the major reservoir for estrogen production after menopause.
- History of Breast Lesions: Women with a history of benign growing breast lesions have an increased risk of ER-positive breast cancer.
Recommendations To Reduce Risk Of ER-positive Breast Cancer
Diet
Some foods like soya, red meat, and dairy have chemicals that function like estrogens.
For this reason, individuals with a high risk of ER-positive breast cancer must avoid them.
They can instead include cancer-fighting foods such as fresh fruits and vegetables (apples, blueberries, asparagus, carrots, tomatoes, etc.), foods rich in fiber (whole grains, oats, etc.), and healthy fats like omega-3 and omega-6 fatty acids.
If you are at high risk of developing ER-positive breast cancer, you must reduce your body fat and limit or completely avoid saturated fats, alcohol, and red meat.
Exercise
Physical activity and regular exercise reduce ER-positive breast cancer risk.
Drugs
Aromatase-inhibitor drugs are effective in preventing ER-positive breast cancer.
Note: Aromatase inhibitors should be consumed only upon your medical practitioner's advice.
BRCA Screening
A BRCA genetic test can help find out your risk for ER-positive breast cancer. Routine breast cancer screening is recommended for those found to be at high risk based on their genetic profile.
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Summary
- Breast cancers that grow in response to estrogen are known as Estrogen Receptor-positive or ER-positive breast cancers.
- ER-positive breast cancers are more common and constitute around 80% of all diagnosed breast cancer cases.
- Hormone therapy and drugs like Tamoxifen and aromatase inhibitors are used to treat ER-Positive breast cancers.
- Abnormal changes in genes like BRCA1, BRCA2, CYP1A1, and ESR1 are associated with an increased risk of developing ER-positive cancer and a poorer prognosis.
- A few non-genetic factors that increase one's risk of developing ER-positive breast cancer include older age (above 50), longer lifetime exposure to estrogen, alcohol consumption, higher BMI, and history of benign breast lesions.
- You can reduce your risk of ER-positive breast cancer by following a healthy diet loaded with fruits and vegetables, exercising regularly, and going for regular screenings.
