Abortion and Female Cancer Risks among Women Aged 20 to 45 Years: A 10-Year Longitudinal Population-Based Cohort Study in Taiwan

Int J Environ Res Public Health. 2023 Feb 19;20(4):3682. doi: 10.3390/ijerph20043682.

Abstract

Background: Female cancers, including breast, cervical, uterine, and ovarian cancer, remain among the ten most common cancers among women worldwide, but the relationship between female cancers and abortion from previous studies is inconsistent. This study aimed to investigate risks of incident female cancers among women aged 20 to 45 years who underwent abortion in Taiwan compared with those who did not.

Method: A longitudinal observational cohort study was conducted using three nationwide population-based databases in Taiwan, focusing on 20- to 45-year-old women, with 10 years of follow-up. Matched cohorts were identified with propensity score 1-to-3 matching between 269,050 women who underwent abortion and 807,150 who did not. Multivariable Cox proportional hazard modeling was used for analysis after adjusting for covariates including age, average monthly payroll, fertility, diabetes mellitus, polycystic ovarian syndrome, endometrial hyperplasia, endometriosis, hormone-related drugs, and Charlson comorbidity index.

Results: We found lower risk of uterine cancer (hazard ratio [HR]: 0.77, 95% CI: 0.70-0.85) and ovarian cancer (HR: 0.81, 95% CI: 0.75-0.88), but no significant difference in risk of breast cancer or cervical cancer, among matched abortion compared with non-abortion cohorts. Regarding subgroup analysis, cervical cancer risk was higher for parous women who underwent abortion, and uterine cancer risk was lower for nulliparous women who underwent abortion compared with non-abortion groups.

Conclusions: Abortion was related to lower uterine and ovarian cancer risk but was not associated with risks of incident breast cancer or cervical cancer. Longer follow-up may be necessary to observe risks of female cancers at older ages.

Keywords: abortion; female cancer risk; women’s health.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abortion, Spontaneous*
  • Adult
  • Breast Neoplasms*
  • Cohort Studies
  • Female
  • Humans
  • Middle Aged
  • Ovarian Neoplasms*
  • Pregnancy
  • Risk Factors
  • Taiwan
  • Uterine Cervical Neoplasms*
  • Uterine Neoplasms*
  • Young Adult

Grants and funding

This study is supported by Kaohsiung Municipal Ta-Tung Hospital (KMTTH-110-012). It is partially supported by: the Ministry of Science and Technology grant (MOST 109-2423-H-037-001-SS3 and MOST 111-2410-H-037-011-); Kaohsiung Medical University Research Center Grant (KMU-M108007, KMUTC109B08, KMU-TC109A01-1, KMUTC110B05); the Research Center for Precision Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan from The Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan; and by the Kaohsiung Medical University Research Center Grant (KMU-TC111A01 and KMUTC111IFSP01). The authors also wish to thank the Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital and the Center for Big Data Research, Kaohsiung Medical University for providing administrative and funding support. None of the above had any role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.