A common treatment in what is called hormone-dependent breast cancer is the use of drugs that block estrogen from attaching to estrogen receptors. This is because estrogen has been shown to help cancer cells grow and spread.
Now, researchers from Brigham and Women’s Hospital and the University of Miami Miller School of Medicine may have discovered additional receptors that play a role in helping or worsening breast cancer, and the vitamin D receptor is one that might help.
The researchers compared the makeup of more than 15,000 normal breast cells with 3,157 breast tumors.
They found 11 new cell types in normal breast cells that were previously undefined. These cell types were further classified into four new hormonal groups (defined as HR 0, 1, 2 and 3) each with vitamin D, androgen and estrogen hormone receptors.
In looking at the breast tumors, the researchers found that the tumors were similar to one of the 11 new cell types they discovered. Additionally, patients with breast tumors receiving hormone treatments had different responses and survival rates based on if their cell types were HR 0, 1, 2 or 3.
This means that while estrogen is a common treatment in breast cancer, there is potential that hormone therapy targeting vitamin D and androgen may also be effective. With vitamin D, the researchers specified that the treatment would be to stimulate vitamin D activity in the vitamin D receptors. With androgen, the treatment would be more complicated with some patients needing stimulated androgen receptors, and others needing the receptors blocked.
“Since at least 50 percent of patients with breast cancer express all three receptors – estrogen, androgen and vitamin D in their tumor cells, this may allow clinicians to consider triple hormone treatments, which is a new concept, as opposed to treating patients by targeting only estrogen receptors,” said lead researcher Dr. Sandro Santagata.
“There are tumors called triple-negative breast carcinomas, which cannot be treated with conventional endocrine-targeted therapies. The study results suggest that two-thirds of these patients may be candidates for androgen and vitamin D-targeted hormone therapy.”
Therapies will still need to be developed, but this research provides basis for potentially future novel treatments.
Maki, J. Researchers discover new hormone receptors to target when treating breast cancer. Brigham and Women’s Hospital, 2014.