Original paper

Cancer Causes & Control

, Volume 25, Issue 2, pp 227-236

A meta-analysis of the association between induced abortion and breast cancer risk among Chinese females

  • Yubei HuangAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
  • , Xiaoliang ZhangAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
  • , Weiqin LiAffiliated withProject Office, Tianjin Women’s and Children’s Health Center
  • , Fengju SongAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
  • , Hongji DaiAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
  • , Jing WangAffiliated withDepartment of Social Medicines and Health Service Management, School of Public Health, Tianjin Medical University
  • , Ying GaoAffiliated withDepartment of Social Medicines and Health Service Management, School of Public Health, Tianjin Medical University
  • , Xueou LiuAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
  • , Chuan ChenAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
    • , Ye YanAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education
    • , Yaogang WangAffiliated withDepartment of Social Medicines and Health Service Management, School of Public Health, Tianjin Medical University
    • , Kexin ChenAffiliated withDepartment of Epidemiology and Biostatistics, Tianjin Medical University Cancer Hospital and Institute, National Clinical Research Center for CancerKey Laboratory of Cancer Prevention and TherapyKey Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education Email author 

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Abstract

Objective

To evaluate the association between induced abortion (IA) and breast cancer risk among Chinese females.

Methods

We searched three English databases (PubMed, ScienceDirect, and Wiley) and three Chinese databases (CNKI, WanFang, and VIP) for studies up to December 2012, supplemented by manual searches. Two reviewers independently conducted the literature searching, study selection, and data extraction and quality assessment of included studies. Random effects models were used to estimate the summary odds ratios (ORs) and the 95 % confidence intervals (CIs).

Results

A total of 36 articles (two cohort studies and 34 case–control studies) covering 14 provinces in China were included in this review. Compared to people without any history of IA, an increased risk of breast cancer was observed among females who had at least one IA (OR = 1.44, 95 % CI 1.29–1.59, I 2 = 82.6 %, p < 0.001, n = 34). No significant publication bias was found among the included studies (Egger test, p = 0.176). The risk increased to 1.76 (95 % CI 1.39–2.22) and 1.89 (95 % CI 1.40–2.55) for people who had at least two IAs and at least three IAs, respectively. Subgroup analyses showed similar results to the primary results. Meta-regression analysis of the included studies found that the association between IA and breast cancer risk attenuated with increasing percent of IA in the control group (β = −0.022, p < 0.001).

Conclusion

IA is significantly associated with an increased risk of breast cancer among Chinese females, and the risk of breast cancer increases as the number of IA increases. If IA were to be confirmed as a risk factor for breast cancer, high rates of IA in China may contribute to increasing breast cancer rates.

Keywords

Induced abortion Breast cancer Systematic review Meta-analysis