What cancers does hormone therapy treat?

Mainly breast cancer and prostate cancer. Those are the two cancers that commonly use hormones as fuel, so cutting off the fuel slows them down.

Hormone therapy is also called hormonal therapy, hormone treatment, or endocrine therapy. It works in one of two ways. Some drugs stop your body from making a hormone. Others let the hormone exist but block it from acting on cells.

Breast cancer, and the test that decides

Not every breast cancer responds. It depends on whether the cancer cells carry hormone receptors, which are docking points for estrogen or progesterone.

Pathologists test tumor tissue for estrogen receptors, called ER, and progesterone receptors, called PR. If either is present the cancer is called hormone receptor positive. About 80% of people diagnosed with breast cancer have this kind. Tumors that lack these receptors do not respond to hormone therapy at all, so it is not offered.

The drugs sort into a few groups. Tamoxifen blocks the estrogen receptor. It is used both before and after menopause.

Aromatase inhibitors block an enzyme the body uses to make estrogen. They include anastrozole, letrozole, and exemestane. They are mainly for women past menopause. The ovaries of younger women make too much of that enzyme to block well. A younger woman can still take one if it is paired with a drug that shuts down her ovaries.

Fulvestrant goes further. It blocks estrogen receptors and destroys them. It is used only after menopause.

Men can get breast cancer too. A man with advanced breast cancer treated with an aromatase inhibitor is also given a drug such as goserelin or leuprolide.

Prostate cancer, and why it stops working

Prostate cancer runs on androgens, the male sex hormones. The main ones are testosterone and dihydrotestosterone. They attach to a docking point called the androgen receptor. That switches on genes telling prostate cells to grow.

The usual first move is androgen deprivation therapy, or ADT. It lowers the testosterone made by the testicles. Other drugs block androgens from acting anywhere in the body. Still others shut down androgen production body-wide, including inside the cancer cells.

There is an honest limit here. Most prostate cancers stop responding in time. They are then called castration resistant, which means they grow even when androgen levels are very low. Newer hormone drugs can still treat some of those.

Where else it appears

The picture is a little wider than breast and prostate. Endometrial cancer starts in the lining of the uterus. It is also treated with hormone therapy when tests show the cells carry hormone receptors. Drugs, surgery, or radiation may be used to cut hormone output or block hormone action.

Hormone therapy is rarely the whole plan. It is most often paired with other treatments. It can shrink a tumor before surgery or radiation. It can lower the chance of return afterward. It can attack cancer that has come back or spread. It is also used purely to ease symptoms, for example in men with prostate cancer who cannot have surgery or radiation.

How it is given, and what it costs your body

It comes as pills you swallow, as shots into a muscle or under the skin, or as surgery to remove the organs that make the hormones, meaning the ovaries or the testicles.

Side effects follow from the hormone loss. Men often get hot flashes, weakened bones, diarrhea, nausea, tender or enlarged breasts, and fatigue. Many also lose interest in sex or the ability to have it. Women often get hot flashes, vaginal dryness, changed periods before menopause, less interest in sex, nausea, mood changes, and fatigue. Weight gain is common with prostate hormone therapy. Ask about a dietitian if it becomes a problem.

Progress is tracked differently for each. In prostate cancer, regular PSA blood tests should stay flat or fall. A rising PSA can mean the treatment has stopped working. In breast cancer, you get regular exams of the neck, underarm, chest, and breast. You also get mammograms, and sometimes other scans or lab tests.

Sources

https://www.cancer.gov/about-cancer/treatment/types/hormone-therapy

https://www.cancer.gov/types/breast/breast-hormone-therapy-fact-sheet

https://www.cancer.gov/types/prostate/prostate-hormone-therapy-fact-sheet

https://www.cancer.gov/types/uterine/patient/endometrial-treatment-pdq