New ER+ Breast Cancer Treatment Discovered
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ER+ Breast Cancer Treatment
Researchers have discovered a new way of treating the ER positive breast cancer. Assuming that tumor cells are heterogeneous, scientists were able to create cellular models that are very similar to ER positive breast cancer. The study was conducted by researchers at the University of Colorado Cancer Center and published in the journal Breast Cancer Research and Treatment.
ER positive breast cancer means that the tumor is composed of cells that have receptors for estrogen. ER positive breast cancer develops in response to estrogen action. In other words, this type of breast cancer may respond to hormone therapy, that is by blocking of estrogen receptors. But not all breast cancers respond to hormone therapy because the tumor is composed of heterogeneous cells. Researchers have used in the study samples of human breast cancer tissue taken after surgery, then they implanted this tissue to animals models. The samples have maintained their heterogeneity even after implantation in animal models.
Breast cancer can be estrogen or progesterone receptor positive, HER2-positive, triple positive (ie positive estrogen receptors, progesterone and HER2) or triple negative (no receptors for estrogen, progesterone or HER2).
Researchers’ hypothesis was that ER positive tumor is not composed only of ER positive cells. Tumor cells may have other types of cells, besides the ER positive, that have other mechanisms of action. Therefore, experiments on cellular models that test drugs have better outcomes than when drugs are administered to human models. Moreover, administration of estrogen receptors blockers leads to cell damage but does not destroy ER negative cells, which in time become the dominant type of cells. Therefore, these cells are ER negative and more difficult to deal with.
Carol Sartorius, PhD, investigator at the CU Cancer Center, associate professor at the CU School of Medicine, and the paper’s senior author, says the solution is that the drugs target these unique features of the tumor. By using cellular models which are similar to human models, researchers can test the accuracy of new drugs used to treat ER positive breast cancer.
In terms of hormone therapy, it is usually given, after removal (surgery) or after tumor destruction (with chemotherapy or radiotherapy) to kill tumor cells left or to prevent relapse. Of the drugs used during the endocrine therapy, the most common are tamoxifen and aromatase inhibitors. Tamoxifen is an estrogen receptor antagonist, while aromatase inhibitors inhibit the synthesis of estrogen hormones. It should be noted however that aromatase inhibitors are effective only in post-menopausal women.