Can Hormone Therapy Treat Breast Cancer?

There’s no one best way to treat breast cancer. So, doctors are always looking for better ways to do it – including hormone therapy.

Specific breast cancer cells have proteins, or receptors, that attach to hormones like estrogen and progesterone, which helps them grow.

Hormone therapy may help prevent hormones from attaching to receptors on cancer cells. It may also decrease your body’s production of the hormones that encourage cancer growth. Hormone therapy can reach cancer cells almost anywhere in the body and not just in the breast.

The key? Stop hormones from attaching to proteins.

Researchers now can break down breast cancer into different subtypes, based on the tumor’s receptor status (positive or negative).

Hormone receptor-positive cancer patients have cells with receptors, or proteins, that attach to the estrogen (called ER-positive cancers) and/or progesterone (called PR-positive cancers). In these types of cancers, high estrogen levels help the cancer cells grow and spread.

Approximately 66% of breast cancers are hormone receptor-positive. Hormone therapy is recommended for women with hormone receptor-positive breast cancers. It the tumor is not affected by hormones in the blood, this therapy won’t help.

Triple-negative breast cancer, which is breast cancer without ER or PR positive receptors and without HER2 positive receptors, doesn’t respond to hormone therapy. Clinical studies are ongoing, looking at immunotherapy and targeted treatment for these cancers.

When do doctors use hormone therapy?

Typically, doctors advise this therapy after surgery to help reduce the risk of cancer coming back. Sometimes it is used before surgery to get a jump on treatment efforts. Treatment usually lasts for at least five years. This therapy may be used to treat cancer that has come back, or that has spread to other parts of a person’s body.

The types – and goals – of hormone therapy

• Medicines to stop estrogen from stimulating breast cancer cells to grow.
  • Tamoxifen: This medicine stops estrogen from connecting to the cancer cells and telling them to grow and divide. For women with ER-positive breast cancer, tamoxifen after surgery can help lower the chances of cancer coming back and increase the chances of living longer. It can also reduce the risk of getting new cancer in the other breast. For women with hormone-positive breast cancer that has spread, tamoxifen can often help slow or stop the growth of cancer, and might even shrink some tumors.
  • Fulvestrant (Faslodex): This blocks and damages estrogen receptors. Doctors use it to treat metastatic breast cancer, usually, after other hormone drugs have stopped working.
    
• Treatments to lower estrogen levels, which can help slow cancer’s growth or help prevent it from coming back. These medications include:
  • Aromatase inhibitors (AIs): AIs work by blocking aromatase from making estrogen.
  • Ovarian suppression
    Your ovaries are your primary source of estrogen. This treatment removes or shuts down the estrogen creation. This  allows doctors to use some other hormone therapies, such as AIs. Through surgery, they may permanently remove the ovaries. Or, you might take a drug that stops the signal that your body sends to your ovaries to make estrogen, and causes temporary menopause.

In 2015, the FDA approved a targeted therapy commonly marketed as Ibrance. When combined with a specific hormone therapy, doctors use it to treat advanced or metastatic, hormone-positive, HER2-negative breast cancer.

Mary Jo Blackwood, RN, MPH, is a contributing writer for UMiami Health News.

Medically reviewed by Dr. Alejandra Perez, oncologist at Sylvester Comprehensive Cancer Center.

Tags: aromatase inhibitors, breast cancer clinical trials, estrogen-receptor positive, HER2-negative, palbociclib