Young women with previous breast cancer can safely pause endocrine therapy for up to two years to attempt pregnancy, according to a landmark international study. 

Results from the POSITIVE trial suggest temporary interruption of endocrine therapy following stage I-III hormone receptor-positive breast cancer had no negative effects among those who wished to conceive. 

US-led researchers examined outcomes for 497 eligible women aged 42 and under who had received adjuvant endocrine therapy — mostly tamoxifen — for 18-30 months and were followed for pregnancy status after a three-month washout period. 

During an average 3.5 years’ follow-up, 74% of participants had at least one pregnancy and 64% had at least one live birth, with a total of 365 infants born.