Young Women Can Safely Pause Hormonal Therapy To Attempt Pregnancy

Young women diagnosed with early-stage, hormone receptor-positive breast cancer who temporarily stopped hormonal therapy to try to become pregnant didn’t have higher rates of the cancer coming back (recurrence) than women who didn’t pause hormonal therapy, and many of the women who paused treatment delivered healthy babies, according to results from the POSITIVE trial.

The research was presented at the San Antonio Breast Cancer Symposium (SABCS).

Pregnancy and breast cancer treatment

According to the latest statistics from the American Cancer Society, about 5% of new DCIS and invasive breast cancer cases are diagnosed in women younger than 40. For a number of these younger women, being able to have a child one day is extremely important.

Studies have shown that becoming pregnant after breast cancer treatment is safe. Still, many younger women who want to have children are worried that treatment may affect their ability to conceive.

Younger women diagnosed with early-stage, hormone receptor-positive breast cancer commonly take hormonal therapy medicine, and this treatment may last for five to 10 years. Waiting that long to try to conceive can be a concern for women who would like to have children someday.

“This is a critical issue for our young patients,” said Ann Partridge, MD, MPH, professor of medicine at Harvard Medical School and vice chair of medical oncology at the Dana-Farber Cancer Institute, who presented the results. Dr. Partridge also is a member of the Breastcancer.org Professional Advisory Board.

The POSITIVE (Pregnancy Outcome and Safety of Interrupting Therapy for Women With Endocrine Responsive Breast Cancer) trial was designed to see if recurrence rates were different between younger women who temporarily stopped taking hormonal therapy to try to get pregnant and younger women who didn’t pause hormonal therapy.

The study enrolled 516 women diagnosed with early-stage, hormone receptor-positive breast cancer between December 2014 and December 2019. All the women were prescribed hormonal therapy for five to 10 years after surgery.

Of the women in the study:

·     half were younger than 37 and half were older, but all the women were 42 or younger

·     75% had never given birth before joining the study

·     94% were diagnosed with stage I or stage II breast cancer

·     62% received chemotherapy

The women took different types of hormonal therapy:

·     42% took only a SERM (selective estrogen receptor modulator), such as tamoxifen

·     36% took a SERM and a GnRH analogue, such as Zoladex (chemical name: goserelin), to suppress ovarian function

·     16% took an aromatase inhibitor and a GnRH analogue

The women took hormonal therapy medicine for 18 to 30 months and then stopped taking it. Then there was what the researchers called a three-month wash-period: the women didn’t take hormonal therapy for three months, but also weren’t trying to get pregnant so any traces of hormonal therapy medicine could get out of their bodies. After the wash-out period, the women didn’t take hormonal therapy for up to two more years to allow them to get pregnant, give birth, and breastfeed.

After about 3.5 years of follow-up, 8.9% of the women had a recurrence, which was similar to the 9.2% recurrence rate of 1,499 women taking hormonal therapy for early-stage breast cancer in two other large studies, the Suppression of Ovarian Function Trial (SOFT) and the Tamoxifen and Exemestane Trial (TEXT).

Because 19 women withdrew from the study or didn’t come to later follow-up appointments, the researchers looked at information from the remaining 497 women to see how many of them became pregnant.

Overall, 507 total pregnancies were confirmed during the study, and 368 (74%) of 497 women became pregnant once:

·     70% of the women became pregnant within two years

·     86% of the women who became pregnant had at least one live birth

·     19% of the women had at least one miscarriage

·     3% of the women had at least one abortion

The rate of birth defects was low — 2% — and any birth defects were not clearly associated with hormonal therapy treatment.

After four years of follow-up:

·     8% of the women had a cancer recurrence or died before restarting hormonal therapy

·     76% of the women restarted hormonal therapy

·     15% of the women had not restarted hormonal therapy

“We plan to follow the women in the study until 2029 to monitor their estrogen therapy resumption and disease outcomes,” Dr. Partridge explained during a media briefing on the results. “These data stress the need to incorporate patient-centered reproductive healthcare in the treatment and follow-up of young women with breast cancer.”

What this means for you

If you’re a younger woman who’s been diagnosed with early-stage, hormone receptor-positive breast cancer and are concerned about having a child, the POSITIVE trial findings offer some important and reassuring information.

The short-term follow-up results compellingly suggest that temporarily stopping hormonal therapy to try to conceive a child doesn’t increase the risk of recurrence. The results also strongly suggest that taking hormonal therapy isn’t linked to birth defects.

If having a child is important to you, it makes sense to talk to your doctor about these results and how they can apply to your unique situation.

Source: Breastcancer.org.