The prognosis of women diagnosed with breast cancer before, during and after pregnancy: a meta-analysis

Abstract

Objective: Previous meta-analyses have examined the prognosis of women with pregnancy-associated breast cancer (PABC) as well as pregnancy that follows breast cancer diagnosis. Since then, many additional studies have been performed. We conducted an updated meta-analysis to examine the prognosis for women who become pregnant before, during and after a diagnosis of breast cancer. We also performed analyses on the various subgroups within PABC such as pregnancy and postpartum cases, as well as on time periods postpartum.

Methods: We identified studies that reported on overall (OS) and disease-free survival (DFS) in patients diagnosed with breast cancer during pregnancy or up to 5 years postpartum from four electronic databases. We also identified studies that reported on OS and DFS where pregnancy up to 5 years occurred after a breast cancer diagnosis.

Results: 41 studies met our inclusion criteria (cases = 4929; controls = 61,041) for pregnancy occurring during or before breast cancer diagnosis. There was an overall increased risk of death amongst patients compared to non-pregnant controls [HR 1.57; 95 % CI 1.35-1.82]. Subgroup analysis indicated poor survival outcomes for those diagnosed either during pregnancy or postpartum (PABC) [HR 1.46; 95 % CI 1.17-1.82] as well as those diagnosed during pregnancy alone [HR 1.47; 95 % CI 1.04-2.08]. Those diagnosed postpartum had the poorest overall survival [HR 1.79; 95 % CI 1.39-2.29]. Similarly, patients with PABC had decreased DFS compared to controls [HR 1.51; 95 % CI 1.22-1.88]. Those diagnosed postpartum were the most at risk of disease progression or relapse [HR 1.86; 95 % CI 1.17-2.93]. 19 studies met our inclusion criteria (cases = 1829; controls = 21,907) for pregnancy following breast cancer diagnosis. Such women had a significantly reduced risk of death compared to those who did not become pregnant [pHR 0.63; 95 % CI 0.51-0.79]. A subgroup analysis to account for the "healthy mother effect" generated similar results [pHR 0.65; 95 % CI 0.52-0.81].

Conclusion: Pregnancy that occurs before or concurrently with a diagnosis of breast cancer is more likely to result in death and decreased disease-free survival. On the other hand, pregnancy occurring after a breast cancer diagnosis reduces the risk of death.

Keywords: Breast cancer; Gestation; Meta-analysis; PABC; Postpartum; Pregnancy; Pregnancy-associated breast cancer.