Abortion and Female Cancer Risks among Women Aged 20 to 45 Years: A 10-Year Longitudinal Population-Based Cohort Study in Taiwan
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.
Funding
Kaohsiung Municipal Ta-Tung Hospital Grant KMTTH-110-012Kaohsiung Municipal Ta-Tung Hospital Grant MOST 109-2423-H-037-001-SS3Kaohsiung Municipal Ta-Tung Hospital Grant MOST 111-2410-H-037-011-Kaohsiung Municipal Ta-Tung Hospital Grant KMU-M108007Kaohsiung Municipal Ta-Tung Hospital Grant KMUTC109B08Kaohsiung Municipal Ta-Tung Hospital Grant KMU-TC109A01-1Kaohsiung Municipal Ta-Tung Hospital Grant KMUTC110B05Kaohsiung Municipal Ta-Tung Hospital Grant KMU-TC111A01Kaohsiung Municipal Ta-Tung Hospital Grant KMUTC111IFSP01the Ministry of Science and Technology grant Grant KMTTH-110-012the Ministry of Science and Technology grant Grant MOST 109-2423-H-037-001-SS3the Ministry of Science and Technology grant Grant MOST 111-2410-H-037-011-the Ministry of Science and Technology grant Grant KMU-M108007the Ministry of Science and Technology grant Grant KMUTC109B08the Ministry of Science and Technology grant Grant KMU-TC109A01-1the Ministry of Science and Technology grant Grant KMUTC110B05the Ministry of Science and Technology grant Grant KMU-TC111A01the Ministry of Science and Technology grant Grant KMUTC111IFSP01Kaohsiung Medical University Research Center Grant Grant KMTTH-110-012Kaohsiung Medical University Research Center Grant Grant MOST 109-2423-H-037-001-SS3Kaohsiung Medical University Research Center Grant Grant MOST 111-2410-H-037-011-Kaohsiung Medical University Research Center Grant Grant KMU-M108007Kaohsiung Medical University Research Center Grant Grant KMUTC109B08Kaohsiung Medical University Research Center Grant Grant KMU-TC109A01-1Kaohsiung Medical University Research Center Grant Grant KMUTC110B05Kaohsiung Medical University Research Center Grant Grant KMU-TC111A01Kaohsiung Medical University Research Center Grant Grant KMUTC111IFSP01the 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 Grant KMTTH-110-012the 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 Grant MOST 109-2423-H-037-001-SS3the 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 Grant MOST 111-2410-H-037-011-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 Grant KMU-M108007the 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 Grant KMUTC109B08the 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 Grant KMU-TC109A01-1the 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 Grant KMUTC110B05the 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 Grant KMU-TC111A01the 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 Grant KMUTC111IFSP01the Kaohsiung Medical University Research Center Grant Grant KMTTH-110-012the Kaohsiung Medical University Research Center Grant Grant MOST 109-2423-H-037-001-SS3the Kaohsiung Medical University Research Center Grant Grant MOST 111-2410-H-037-011-the Kaohsiung Medical University Research Center Grant Grant KMU-M108007the Kaohsiung Medical University Research Center Grant Grant KMUTC109B08the Kaohsiung Medical University Research Center Grant Grant KMU-TC109A01-1the Kaohsiung Medical University Research Center Grant Grant KMUTC110B05the Kaohsiung Medical University Research Center Grant Grant KMU-TC111A01the Kaohsiung Medical University Research Center Grant Grant KMUTC111IFSP01Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMTTH-110-012Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant MOST 109-2423-H-037-001-SS3Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant MOST 111-2410-H-037-011-Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMU-M108007Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMUTC109B08Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMU-TC109A01-1Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMUTC110B05Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMU-TC111A01Division of Medical Statistics and Bioinformatics, Department of Medical Research, Kaohsiung Medical University Hospital Grant KMUTC111IFSP01the Center for Big Data Research, Kaohsiung Medical University Grant KMTTH-110-012the Center for Big Data Research, Kaohsiung Medical University Grant MOST 109-2423-H-037-001-SS3the Center for Big Data Research, Kaohsiung Medical University Grant MOST 111-2410-H-037-011-the Center for Big Data Research, Kaohsiung Medical University Grant KMU-M108007the Center for Big Data Research, Kaohsiung Medical University Grant KMUTC109B08the Center for Big Data Research, Kaohsiung Medical University Grant KMU-TC109A01-1the Center for Big Data Research, Kaohsiung Medical University Grant KMUTC110B05the Center for Big Data Research, Kaohsiung Medical University Grant KMU-TC111A01the Center for Big Data Research, Kaohsiung Medical University Grant KMUTC111IFSP01