Hormones can present challenges when it comes to cancer treatment. That’s because certain cancers are fed by hormones, helping them to grow and spread more quickly. Breast cancers, for example, are often fueled by estrogen and/or progesterone; prostate cancers rely on androgen.

To treat these cancers, doctors may decide to block or interfere with hormone production in order to stop the cancer from spreading, slow it down or decrease the odds it will come back. Adjusting a cancer patient’s hormones in this way is called hormonal therapy. (It goes by a lot of other names, too, such as hormone suppression therapy, hormone deprivation therapy, hormone therapy, anti-hormone therapy or endocrine treatment.)

No matter the label, hormonal therapy may be used in conjunction with other cancer treatments such as surgery, chemotherapy and radiotherapy.

“Hormonal therapy is sometimes used to control cancer growth,” explains Michael Leapman, MD, a urologic oncologist who focuses on the treatment of prostate cancers. Depending on the kind of cancer being treated—breast cancer or prostate cancer, for example—hormonal therapy can be short or long term. “For men [with intermediate and high-risk prostate cancers] receiving radiation, hormonal blockage is given for pre-specified amounts of time. However, men with advanced prostate cancers typically require long-term therapy.”

At Yale Medicine, our oncologists are experts in their specialties. They use the latest research and work collaboratively with multiple specialists to determine how to best treat a patient’s cancer.

• Breast cancer: An estimated 80% of breast cancers are hormone-sensitive (also called hormone-dependent), which means they are fueled by hormones. More specifically, these are called estrogen-receptor-positive or progesterone-receptor-positive breast cancers. These terms mean this particular cancer has estrogen and/or progesterone receptors, which invite hormones to bind to them. Hormone-receptor-negative cancers are not influenced by hormones.
• Prostate cancer: “Most prostate cancers are stimulated by male sex hormones called androgens,” says Dr. Leapman; this is why urologists also refer to this treatment as “androgen deprivation therapy.” These hormones (testosterone and their derivatives) are made in the adrenal glands and testicles. Hormonal therapy for prostate cancer is used in several ways, including as short-term therapy for men prior to and during radiation therapy, as well as for men with advanced or metastatic cancer.

Hormonal therapy is sometimes used to destroy hormone-sensitive cancer cells that have spread (metastasized) to other parts of the body or those that have returned (recurrent cancer).

Hormonal therapy can also be used to ease a cancer patient’s symptoms (such as pain from a large tumor). This is especially helpful for patients who are not able to have surgery or radiotherapy because of other health concerns. 

Hormonal therapy is often given in conjunction with other treatments. The timing varies depending on the tumor, its stage and its location, among other factors:

• Neoadjuvant hormonal therapy is when hormones are given before surgery or radiotherapy. The goal is to make a tumor shrink, so it’s smaller, which can make it easier to treat.
• Adjuvant hormonal therapy is given after the patient has received surgery, radiation therapy or chemotherapy. Given after treatment, hormones decrease the risk of cancer recurring or spreading.

Any disruption to the balance of hormones—whether it occurs naturally or is part of treatment—can cause side effects. The specific side effects that come from blocking a person’s estrogen, progesterone or androgen production will depend on the individual and the type of hormonal therapy they receive. Some common side effects people experience are as follows:

• Mood changes
• Hot flashes
• Loss of libido
• Impotence
• Fatigue
• Decreased bone density
• Breast tenderness or enlargement
• Possible weight gain
• Diarrhea                     

Hormonal therapy can be administered in the following ways:

• Oral medications
• Injectable medications given under the skin
• Surgery to remove or ablate the hormone-producing ovaries (oophorectomy) or testicles (orchiectomy)

Testing and imaging are used to monitor the tumor. Men with prostate cancer will be given regular blood tests called prostate-specific antigen (PSA) tests to measure their hormones. At Yale Medicine, doctors also use a prostate MRI to track prostate cancer.        

For breast cancer, patients are given diagnostic mammograms, breast ultrasounds or breast MRIs as needed, as well as lab tests. For both prostate and breast cancers, doctors monitor hormone levels in the blood to determine how well the treatment is working. If the hormone levels in the blood go up during therapy or if the tumor continues to grow, doctors will know that hormonal therapy isn’t working. However, if hormone levels and the tumor size have decreased, then they know the therapy is having an effect. 

“Yale Medicine’s specialists understand and recognize that hormonal therapy has possible side effects. We are committed to offering solutions to overcome or reduce them,” says Dr. Leapman. Doing so allows our patients to have the best quality of life possible during cancer treatment, he says.