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Meta-Analysis
. 2020 Aug 10;20(1):746.
doi: 10.1186/s12885-020-07248-8.

Prognosis of pregnancy-associated breast cancer: a meta-analysis

Chunchun Shao  1 , Zhigang Yu  2 , Juan Xiao  1 , Liyuan Liu  2 , Fanzhen Hong  3 , Yuan Zhang  4   5 , Hongying Jia  6
Affiliations
Meta-Analysis

Prognosis of pregnancy-associated breast cancer: a meta-analysis

Chunchun Shao et al. BMC Cancer. .

Abstract

Background: Pregnancy-associated breast cancer (PABC) is defined as breast cancer that is diagnosed during pregnancy and/or the postpartum period. Definitions of the duration of the postpartum period have been controversial, and this variability may lead to diverse results regarding prognosis. Moreover, evidence on the dose-response association between the time from the last pregnancy to breast cancer diagnosis and overall mortality has not been synthesized.

Methods: We systematically searched PubMed, Embase, and the Cochrane Library for observational studies on the prognosis of PABC published up to June 1, 2019. We estimated summary-adjusted hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs). Subgroup analyses based on diagnosis time, PABC definition, geographic region, year of publication and estimation procedure for HR were performed. Additionally, dose-response analysis was conducted by using the variance weighted least-squares regression (VWLS) trend estimation.

Results: A total of 54 articles (76 studies) were included in our study. PABC was associated with poor prognosis for overall survival (OS), disease-free survival (DFS) and cause-specific survival (CSS), and the pooled HRs with 95% CIs were 1.45 (1.30-1.63), 1.39 (1.25-1.54) and 1.40 (1.17-1.68), respectively. The corresponding reference category was non-PABC patients. According to subgroup analyses, the varied definition of PABC led to diverse results. The dose-response analysis indicated a nonlinear association between the time from the last delivery to breast cancer diagnosis and the HR of overall mortality (P < 0.001). Compared to nulliparous women, the mortality was almost 60% higher in women with PABC diagnosed at 12 months after the last delivery (HR = 1.59, 95% CI 1.30-1.82), and the mortality was not significantly different at 70 months after the last delivery (HR = 1.14, 95% CI 0.99-1.25). This finding suggests that the definition of PABC should be extended to include patients diagnosed up to approximately 6 years postpartum (70 months after the last delivery) to capture the increased risk.

Conclusion: This meta-analysis suggests that PABC is associated with poor prognosis, and the definition of PABC should be extended to include patients diagnosed up to approximately 6 years postpartum.

Keywords: Dose-response; Meta-analysis; Pregnancy-associated breast cancer; Prognosis; Survival.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Schematic representation of the study selection process
Fig. 2
Fig. 2
Hazard ratios and 95% CIs of studies included in the meta-analysis of OS
Fig. 3
Fig. 3
Hazard ratios and 95% CIs of studies included in the meta-analysis of DFS
Fig. 4
Fig. 4
Hazard ratios and 95% CIs of studies included in the meta-analysis of CSS
Fig. 5
Fig. 5
Dose-response relation between the time from the last delivery to breast cancer diagnosis and the HR of overall mortality
Fig. 6
Fig. 6
Funnel plot to explore the presence of publication bias
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