After surgery, women diagnosed with hormone-receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence). Hormonal therapy medicines work in two ways:
- by lowering the amount of estrogen in the body
- by blocking the action of estrogen on breast cancer cells
There are several types of hormonal therapy medicines. Tamoxifen, a selective estrogen receptor modulator (SERM), is one of the most well-known. Tamoxifen can be used to treat both premenopausal and postmenopausal women. In the early 2000s, the aromatase inhibitors:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
were shown to be more effective at reducing recurrence risk in postmenopausal women and are now used more often than tamoxifen to treat women who’ve gone through menopause. Aromatase inhibitors aren’t commonly used to reduce recurrence risk in premenopausal women.
Most women take hormonal therapy for 5 to 10 years after breast cancer surgery.
Because tamoxifen may cause damage to developing embryos, women taking tamoxifen should not get pregnant and should use an effective non-hormonal type of birth control -- such as condoms, a diaphragm along with spermicide, or a non-hormonal IUD -- while they are taking tamoxifen and for 2 months afterward.
A study has found that concerns about fertility caused about 30% of younger women diagnosed with hormone-receptor-positive, early-stage breast cancer to skip or stop taking tamoxifen.
The research was published online on Aug. 24, 2015 by the JNCI: Journal of the National Cancer Institute. Read the abstract of "Impact of Fertility Concerns on Tamoxifen Initiation and Persistence" (PDF).
The researchers knew that many younger women diagnosed with breast cancer didn’t complete hormonal therapy treatment, but not much research has looked at why this is happening.
The researchers looked at the records of 515 premenopausal women younger than 45 who had been diagnosed with hormone-receptor-positive, early-stage breast cancer from 2007 to 2012. It was recommended that all the women take tamoxifen after surgery.
At diagnosis, 112 of the women had said they wanted to have a child in the future.
The results showed that about 30% of the women either didn’t start taking tamoxifen or stopped taking it before the prescribed 5 years of treatment were completed:
- 71.1% of the women completed the entire 5 years of tamoxifen treatment
- 13.4% (69 women) never started tamoxifen
- 15.5% (80 women) stopped taking tamoxifen early, before the 5 years was up
Besides looking at the medical records, the researchers also did phone interviews with 88 of the women who didn’t start or stopped taking tamoxifen early to find out their reasons for never starting or stopping early.
They found that:
- 35.2% of the women were primarily concerned about future fertility
- 53.4% said they were concerned about side effects
- 11.4% said they didn’t think the treatment offered enough benefits
"Our study points toward the importance of fertility to young breast cancer patients. We need to find a way to bridge the gap between this patient survivorship goal and our concerns as physicians to facilitate the best treatment possible for our patients," said senior study author Jacqueline Jeruss, M.D., Ph.D., associate professor of surgery and biomedical engineering at the University of Michigan.
"For those oncology patients who express a desire for future fertility or a concern about fertility preservation, appropriate counseling and referral to a fertility specialist should be offered at the outset as part of a multidisciplinary treatment plan," she continued. "We should work toward a dialogue where patients can discuss with their physicians issues that are important to them. By creating such a dialogue, we may identify more patients who are willing to complete the recommended course of tamoxifen therapy, though this may involve a treatment delay or hiatus to allow for a pregnancy."
An international study, called the POSITIVE trial, is looking at whether premenopausal women who stop tamoxifen for a period of time to become pregnant and then resume tamoxifen after pregnancy get the same benefits as women who take tamoxifen continuously for 5 years.
If you’re a younger women who wants to have children after breast cancer treatment, it’s important to talk to your doctor about fertility preservation as you are planning your treatment. You also can ask for a referral to a fertility specialist for counseling before treatment begins.
It’s also important to remember that the reality is that hormone-receptor-positive breast cancer can come back. Hormonal therapy after surgery reduces that risk by almost 50%.
For more information on fertility preservation options, visit the Breastcancer.org pages on Fertility and Pregnancy Issues During and After Breast Cancer.
And stay tuned to Breastcancer.org Research News for the latest results from the POSITIVE trial as they become available.