Unlike radiation therapy, which takes aim at cancer cells in a specific area, hormone therapy targets cancer cells throughout the body. There are two types of hormone therapy approaches. The most common uses drugs that change the way hormones work. The other involves surgery to remove the ovaries, which make female hormones.
Some tumors rely on female sex hormones to grow: Research suggests that two-thirds of all breast cancer tumors test positive for estrogen receptors, and roughly two-thirds of these also test positive for progesterone receptors. These tumors are more likely to be susceptible to treatment with hormonal drugs.
Tumors with hormone receptors tend to grow less aggressively, and women with these types of tumors can expect better outcomes. Drugs such as tamoxifen can destroy these tumors by blocking their access to estrogen. Tamoxifen is generally taken for a period of five years, though the ideal length of treatment is still being studied. Side effects are minimal, including a slightly increased risk of uterine cancer or blood clots.
For premenopausal women, another type of hormone therapy can be used. Doctors can remove the ovaries (oopherectomy) or prescribe drugs to prevent the ovaries from cycling and making estrogen. Now that tamoxifen is available, this approach is rarely used. However, researchers are looking at whether this treatment can improve the outcome when added to chemotherapy and tamoxifen.
Hormone therapy is not given to women whose tumors are hormone-receptor negative (do not contain estrogen or progesterone receptors). Instead, these women usually receive chemotherapy alone after surgery. Studies are ongoing to determine the optimal therapy for estrogen-receptor negative tumors.
Questions you may want to ask your doctor about hormone therapy:
- Why do I need this treatment?
- If I need hormone therapy, which would be better for me, drugs or surgery?
- What drugs will I be taking? What will they do?
- Will I have side effects? What can I do about them?
- How long will I be on this treatment?