A new study has found young breast cancer patients who pause their endocrine treatment to try to get pregnant have no increased risk of recurrence in the short term. and most women were able to conceive with more than 60 percent having a baby.

Patients who paused their endocrine therapy experienced short-term rates of breast cancer recurrence similar to women who did not pause therapy for pregnancy, and many went on to conceive and deliver healthy babies, according to results from the POSITIVE clinical trial presented at the 2022 San Antonio Breast Cancer Symposium.

Professor Christobel Saunders, consultant surgeon at Peter Mac and the James Stewart Chair of Surgery at the University of Melbourne was the lead investigator in Australia for the study which enrolled patients from 116 hospitals across 20 countries. 

Forty to 60 percent of patients who are diagnosed with breast cancer at age 40 or younger are concerned about their future fertility, especially if the disease occurs before they could decide whether to become a mother or not.

Young women with early-stage hormone receptor (HR)-positive breast cancer are often treated with endocrine therapy, such as ovarian function suppression, aromatase inhibitors, or selective estrogen receptor modulators.

“This study confirms breast cancer patients who stop hormone therapy to become pregnant did not experience worse short-term recurrence rates,” Professor Saunders said.

“Women now know there is hope if they want a family.”

To examine the impact of pausing endocrine therapy to pursue pregnancy, researchers designed the single-arm POSITIVE clinical trial (Pregnancy Outcome and Safety of Interrupting Therapy for Women with Endocrine Responsive Breast Cancer).

From December 2014 through December 2019, 518 women aged 42 or younger who desired to become pregnant enrolled in the study, opting to pause endocrine therapy for approximately two years to try to get pregnant. Before pausing their treatment, women had completed between 18 and 30 months of adjuvant endocrine therapy.

Researchers found that the percentage of women whose breast cancer came back (8.9%) was comparable to what occurred in patients enrolled in other studies (9.2%).

In addition, with a total of 365 babies born to women in the study, the rates of conception and childbirth were similar to, or higher, than rates in the general population.

The study is sponsored and conducted by the International Breast Cancer Study Group (IBCSG), a division of ETOP-IBCSG Partners Foundation, and by the Alliance for Clinical Trials in Oncology in North America, in collaboration with the Breast International Group (BIG). The study concept was initiated within the BIG-NCTN (National Clinical Trials Network) Endocrine Working Group, then developed, and coordinated globally by the IBCSG to address this important, patient-oriented, unmet medical need.