Do racial differences exist in the association between pregnancy-induced hypertension and breast cancer risk?

ABSTRACT

Background: Previous studies investigating the relationship between pregnancy-induced hypertension (PIH) and breast cancer risk have yielded inconsistent results. Unlike numerous Western studies, studies have reported that PIH may be a risk factor for breast cancer in Western Asian women. To confirm these results, we designed a retrospective population-based cohort study to assess the relationship between PIH and subsequent risk for breast cancer in Taiwan. Methods: Patients with newly diagnosed PIH were selected from the Taiwan National Health Insurance Research Database (NHIRD), and a 1:4 matched cohort of women without PIH based on age and the year of delivery was randomly selected from the same database as the comparison group. The incidence of new-onset breast cancer was assessed in both cohorts. Results: Among the 23.3 million individuals registered in the NHIRD, 26,638 patients with PIH and 106,552 matched controls were identified. The incidence rate of breast cancer was higher in patients with PIH than in the matched controls (incidence rate ratio = 1.09, 95% confidence interval [CI] = 1.09–1.10, p < 0.0001). However, the Kaplan–Meier analysis revealed a similar cumulative incidence rate of breast cancer between the PIH and comparison cohorts (log-rank p = 0.4303). Moreover, results from a multivariate analysis indicated that PIH was not a statistically significant independent risk factor for breast cancer (adjusted hazard ratio = 1.10, 95% CI = 0.87–1.39, p = 0.4247). Conclusions: The present study demonstrated no significant temporal relationship between PIH and risk for subsequent breast cancer in Eastern Asian women.

KEYWORDS:

• Breast cancer
• epidemiology
• gestational hypertension
• preeclampsia
• pregnancy-induced hypertension

Acknowledgment

The authors thank the Economy Company Ltd. for their technical support and National Health Insurance Research Database provided by Statistic Center of Department of Health and Welfare.

Funding

The authors would like to thank the funding provided by Kaohsiung Veterans General Hospital and the Taiwan Health Promotion Administration for the support [grant number VGHKS15-EM4-01].

Declaration of interest

All authors have no any potential conflicts (financial, professional, or personal) that are relevant to the manuscript.

Additional information

Funding

The authors would like to thank the funding provided by Kaohsiung Veterans General Hospital and the Taiwan Health Promotion Administration for the support [grant number VGHKS15-EM4-01].

Notes on contributors

Hong-Tai Chang

Study concept and design (H-T C, L-T L, P-L T); acquisition of data (J-T C, H-T C, W-C H); analysis and interpretation of data and statistical analysis (P-L T); drafting of the manuscript (L-T L, K-H T, L-Y H); critical revision of the manuscript for important intellectual content (L-T L, L-Y H, H-T C); study supervision (P-L T, H-T C).