This study may lead to new therapies for ER-positive breast cancers
A new study may lead to new treatments for breast cancer, which is the most common and deadly breast cancer among women. Researchers at the Garvan Institute of Medical Researchers in Sydney, Australia and colleagues in the United Kingdom found that a protein that stimulates milk production may also be responsible for making breast cancers more aggressive. They published their findings on December 27 in the journal PLOS Biology.
Breast cancer accounts for 23% of total cancer cases and 14% of cancer deaths in women. The protein ELF5 is present in all breast cells. Its purpose is to activate milk production; however, breast cancer cells exposed to the protein become more aggressive. The researchers note that their discovery may lead to new treatments for breast cancer as well as the designing of
new markers that can predict response to therapy. They explain that breast cancer cells cannot respond appropriately to ELF5 and produce milk; rather, they respond to the protein by becoming more aggressive and more resistant to treatment.
For the study, the researchers grew human breast cancer tissues, genetically engineered to contain high amounts of ELF5, in the laboratory and examined their growth. Under the influence of ELF5, the cells proliferated aggressively in the petri dishes.
Many breast cancers are sensitive to the hormone estrogen. This means that estrogen causes the breast cancer tumor to grow. Such cancers have estrogen receptors on the surface of their cells. They are called estrogen receptor-positive cancer or ER-positive cancer. Breast cancer treatment depends on whether the cancer is ER positive. If the cancer is ER positive, anti-hormonal therapies are given that lower estrogen levels in the patient or block estrogen from supporting the growth of the cancer. ER negative patients will not benefit from anti-hormonal therapies. These patients are treated with chemotherapy and radiation.
The researchers found that cancers with estrogen receptors had low levels of ELF5, while those without receptors had significantly higher levels of the protein. Thus, the researchers found that tumors with high ELF5 levels were dependent on ELF5 for their growth. If a method can be developed to block ELF5 in these high ELF5 tumors, it will also impede tumor growth. Since about two thirds of breast cancers are ER positive, blocking ELF could benefit the majority of women suffering from breast cancer.
Over the course of a lifetime, one of eight women will be diagnosed with breast cancer.
Breast Cancer Risk factors one cannot change include:
- Age and gender: The risk of developing breast cancer increases as one ages. The majority of advanced breast cancer cases are found in women over age 50. Women are 100 times more likely to get breast cancer than men.
- Family history of breast cancer: The risk of breast cancer is higher if a woman has a close relative who has had breast, uterine, ovarian, or colon cancer. About 20-30% of women with breast cancer have a family history of the disease.
- Genes: Some women carry genes that make them more prone to developing breast cancer. The most common gene defects are found in the BRCA1 and BRCA2 genes. These genes normally produce proteins that protect a woman from cancer. However, if a parent passes on a defective gene, one has an increased risk for breast cancer. Women with one of these defects have up to an 80% risk of getting breast cancer sometime during their life.
- Menstrual cycle: Women who get their periods early (before age 12) or go through menopause late (after age 55) have an increased risk for breast cancer.
Other risk factors include:
- Alcohol use: Drinking more than 1-2 glasses of alcohol a day may increase the risk for breast cancer.
- Childbirth: Women who have never had children or who had them only after age 30 have an increased risk for breast cancer. Being pregnant more than once or becoming pregnant at an early age reduces the risk of breast cancer.
- DES: Women who took diethylstilbestrol (DES) to prevent miscarriage may have an increased risk of breast cancer after age 40. This drug was given to the women in the 1940s - 1960s.
- Hormone replacement therapy (HRT): A woman may have a higher risk for breast cancer if she received hormone replacement therapy for several years or more.
- Obesity: Obesity has been linked to breast cancer, although this link is controversial. The theory is that obese women produce more estrogen, which can fuel the development of breast cancer.
- Radiation: If a woman received radiation therapy as a child or young adult to treat cancer of the chest area, she has a significantly higher risk for developing breast cancer. The younger one started such radiation and the higher the dose, the higher the risk––especially if the radiation was given when breast development was occurring.
Reference: PLOS Biology
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