What is endometriosis? Hormone

The endometrium is the tissue that lines the uterus. During each menstrual cycle, a new endometrium grows, getting ready for a possible pregnancy. If you don't become pregnant during that cycle, the endometrium sheds, which you know as your menstrual period.

Endometriosis is endometrium tissue that grows outside of the uterus, usually on the ovaries or fallopian tubes, the outer surface of the uterus, the bowels, or other abdominal organs. In rare cases, it can affect other organs and structures in the body.

Endometriosis growths are called “implants.” These implants grow, bleed, and break down with each menstrual cycle, just like the endometrium does. This can cause pain and can make it difficult to become pregnant (infertility). In some cases, scar tissue forms around implants. Scar tissue can also cause pain and infertility and can interfere with an organ's normal function.

How will endometriosis affect me?

Endometriosis is usually a long-lasting (chronic) disease. While some women with endometriosis never have symptoms or problems, others develop mild to severe symptoms or infertility. Between 20% and 40% of women who are infertile have endometriosis. In any given case, it is impossible to know whether endometriosis will get worse, improve, or stay the same until menopause.

Endometriosis growths (implants) go through the same growing, breaking down, and bleeding that the uterine lining (endometrium) goes through with each menstrual cycle. This is why endometriosis pain often starts as mild discomfort a few days before the menstrual period and why it usually improves during the period. But if an endometriosis implant grows in a sensitive area such as the rectum, it can eventually cause constant pain or pain during certain activities such as sex, exercise, or bowel movements.

Endometriosis symptoms often improve during pregnancy, and they usually disappear after menopause. These are times when estrogen levels are low, which slows or stops endometriosis growth. For most women, endometriosis symptoms also improve with hormonal treatments that lower estrogen levels.

How does hormone therapy work?

Hormone therapy reduces estrogen levels in your body. Because of this, you cannot use hormone therapy if infertility is your main concern.

    * Birth control hormones (patch, pills, or ring) control the menstrual cycle. This stops ovulation and endometrium growth and shrinks endometriosis implants. For most women, this therapy is doesn't usually have serious side effects, lowers ovarian cancer risk (which is higher with endometriosis), and can be used long-term until menopause. For more general information on birth control hormones, see Birth control pill, patch, or ring.
    * Gonadotropin-releasing hormone agonist (GnRH-a) therapy (such as Lupron, Synarel, or Zoladex) lowers estrogen to the levels women have after menopause. GnRH-a therapy is limited to a short period of time (3 to 6 months) because it thins the bones, which can lead to osteoporosis. It is usually used with a little added estrogen and progestin (add-back therapy) to prevent bone loss and menopause side effects. Using GnRH-a therapy after surgery may relieve pain for a longer time by preventing the growth of new or returning endometriosis.
    * Progestin creates progestin levels in the body that are similar to pregnancy. This stops monthly ovulation and lowers estrogen, which shrinks endometriosis implants and reduces pain for most women. High-dose progestin (such as the Depo-Provera shot) is not a long-term treatment—two or more years of treatment may weaken your bones. Talk to your doctor about whether the progestin intrauterine device (Mirena) might offer you progestin benefits with lower side effect risks.
    * Danazol therapy lowers estrogen levels and raises male hormone (androgen) levels, which puts the body in a state similar to menopause. This shrinks endometriosis implants and reduces pain for most women. But danazol side effects are usually worse than GnRH-a side effects, making danazol a last-choice therapy.
    * Aromatase inhibitors stop estrogen production. In small studies, aromatase inhibitors have been shown to reduce pain and the chance of endometriosis growths coming back. Aromatase inhibitors may help women with endometriosis who have not had relief with hormonal treatments. Aromatase inhibitors are used in combination with a hormonal treatment (such as birth control hormones or progestin). Long-term use of aromatase inhibitors may cause bone loss. More research needs to be done before it is known how well this treatment works and what the side effects are.

How well does hormone therapy work?

All hormone therapies are effective for 80% to 90% of women. While one may work for you, it won't necessarily work for someone else. You may have to try one, then another, before finding one that works for you. The major differences between hormone therapy options are their side effects. Some, especially danazol, can cause very unpleasant side effects. Others—such as GnRH-a or high-dose progestin—thin the bones, so they cannot be used long-term.

If taking birth control hormones works for you, you can use them for years (unless you plan a pregnancy). Long-term use may prevent endometriosis from getting worse, lower your ovarian cancer risk, and effectively prevent pregnancy. For some women in their 40s, they also improve or prevent perimenopausal symptoms that can make life difficult as menopause approaches.

For some women, hormone therapy offers only a temporary solution because pain relief lasts only a few months after treatment. For others, relief is long-lasting.

Pain recurrence. After treatment with any hormone therapy, endometriosis pain can, but does not always, return:

    * Each year, up to 20% of all women treated will have pain that returns after hormone treatment.
    * About 37% of women who use hormone therapy for mild endometriosis have pain 5 years later.
    * About 74% of women who use hormone therapy for severe endometriosis have pain 5 years later.