INTERNATIONAL BREAST CANCER STUDY GROUP: A study evaluating the pregnancy outcomes and safety of interrupting endocrine therapy for young women with endocrine responsive breast cancer who desire pregnancy


Year of Grant: 2015

Location: Switzerland


According to statistics from Young Survival Coalition, it is estimated that more than 250,000 women diagnosed with breast cancer at age 40 or younger are living in the U.S. alone today. In 2015, more than 13,000 young women will be diagnosed. While breast cancer in young women accounts for a small percentage of all breast cancer cases, the impact of the disease is significant as these patients often have to face the disease before having addressed their family planning.


The best available retrospective evidence suggests that pregnancy after breast cancer does not negatively impact disease outcome in patients with endocrine sensitive breast cancer and is safe for the offspring. However, no definitive information is available to recommend a safe interval from breast cancer diagnosis to pregnancy. Long-term (5-10 years) post-operative endocrine therapy could reduce the possibility of subsequent pregnancies in many of these women.


A global collaboration led by the International Breast Cancer Study Group (IBCSG), this clinical trial will investigate endocrine therapy (ET) interruption to enable conception for young women between 18 and 42 years of age with endocrine responsive early breast cancer, who have received adjuvant ET for 18-30 months and wish to attempt pregnancy.


The two primary objectives are 1) risk assessment for breast cancer relapse associated with temporary interruption of endocrine therapy to permit pregnancy and 2) evaluate factors associated with pregnancy success after interruption of endocrine therapy. The study will also allow for the testing of biologic correlates of pregnancy and disease outcome. Additionally, a psycho-oncology companion study will also explore related psychological distress, fertility concerns and decisional conflicts.


A total of 500 patients are planned for recruitment into the trial, which will last approximately 4 years. To reach this accrual, a consortium of more than 80 investigators across 24 countries has been built. The team had previously conducted a global survey from September 2012 to March 2013 to explore young patients’ interest in a study addressing pregnancy after breast cancer. Survey findings indicate that maternity desire, especially at diagnosis, is common in young women and should be adequately addressed by healthcare providers.