Exclusion of pregnant and lactating persons from breast cancer clinical trials: a review of active trials registered on ClinicalTrials.gov.

Introduction: Treatment of pregnancy-associated breast cancer is complex, as providers try to balance risks to the pregnant person and the developing fetus. Given increased case fatality and increasing incidence, there is a pressing need understand the efficacy and safety of different treatment regimens in this population; however, pregnant and lactating people have traditionally been excluded from participating in randomized controlled trials (RCTs). Given recent efforts to expand the inclusion criteria for oncology RCTs, this study aimed to review the inclusion/exclusion criteria of current breast cancer RCTs to assess what proportion of trials permitted enrollment of pregnant and lactating persons.

Material And Methods: We conducted a comprehensive search of ClinicalTrials.gov in January 2022 to identify interventional studies of breast cancer in adults that were actively recruiting. The primary outcomes were the exclusion of pregnant and lactating people.

Results: The search identified 1706 studies, of which 1451 met eligibility criteria. Overall, 69.4% and 54.8% of studies excluded pregnant and lactating people, respectively. The exclusion of pregnant and lactating persons differed by study characteristics but extended across all trial designs, locations, phases and interventions. Exclusion of pregnant and lactating persons was most common in trials where the intervention was biological (86.3%), drug (83.5%) or radiation (81.5%).

Conclusions: The exclusion of pregnant and lactating people from clinical trials contributes to evidence gaps in how to treat this population. A paradigm shift is needed that focuses on how research can be used to protect pregnant people from future harms, instead of protecting pregnant people from research-related risks.