O-277 Safety of pregnancy after early breast cancer in young women with hormone receptor-positive disease: a systematic review and meta-analysis

Abstract Study question Is it safe to have a pregnancy in women with prior history of hormone receptor-positive early breast cancer? Summary answer Pregnancy following breast cancer treatments in young women with history of hormone receptor-positive disease is safe with no detrimental effect on patients’ prognosis. What is known already Breast cancer is the most common malignancy diagnosed in women of reproductive age. Both physicians and patients continue to have concerns about a potential detrimental effect of pregnancy after breast cancer, particularly in the setting of hormone receptor-positive disease. In recent years, several studies have demonstrated the safety of pregnancy after anticancer treatments in breast cancer survivors. Study design, size, duration A systematic literature search of Medline, Embase and Cochrane library with no language or date restriction up to January 1st, 2023, was performed following the PRISMA guidelines. We included retrospective or prospective case-control and cohort studies as well as prospective clinical trials comparing survival outcomes of premenopausal female patients with reported pregnancy or not after diagnosis and treatment for hormone receptor-positive breast cancer. Participants/materials, setting, methods Included patients were childbearing potential age women with a prior history of hormone receptor-positive early breast cancer. Outcomes of interest were disease-free survival and overall survival. Hazard ratios (HR) with 95% confidence intervals (CI) were extracted. Higgins I2 index was used to evaluate the degree of inconsistency in the results of the included studies. Pooled HRs were considered statistically significant with a P value of < 0.05 (two-sided). Main results and the role of chance Eight studies were eligible to be included in the final analysis. A total of 3,805 patients with hormone receptor-positive breast cancer were included in these studies, of whom 1,285 had a pregnancy after treatments. Median follow-up of the included studies ranged from 3.81 years to 15.8 years. In three studies (n = 987 patients) reporting on disease-free survival outcomes, no difference was observed between patients with or without a subsequent pregnancy (HR 0.96, 95% CI 0.75 – 1.24, p = 0.781). Six studies (n = 3,504 patients) reported outcomes in terms of overall survival: patients with a pregnancy after breast cancer had better overall survival compared with those without a pregnancy (HR 0.46, 95% CI 0.27 – 0.77, p < 0.05). At the subgroup analysis on timing of pregnancy, no detrimental effect of pregnancy after breast cancer in terms of disease-free survival was observed for patients achieving a late pregnancy (defined as 2 or 5 years after diagnosis) as compared to patients without a subsequent pregnancy (HR 1.08, 95% CI 0.80 – 1.46, p = 0.611). Increased disease-free survival was observed in patients with an early pregnancy (HR 0.63, 95% CI 0.47 – 0.85, p < 0.05). Limitations, reasons for caution This meta-analysis is based on abstracted data and most of the studies are retrospective cohort studies. Median follow-up in a large proportion of the studies was shorter than 10 years. Adjuvant hormone therapy before and after pregnancy was not available in many studies included. Wider implications of the findings Our results strengthen the evidence that having a pregnancy in women with prior history of hormone receptor-positive breast cancer is safe. Trial registration number not applicable