Risks of breast, endometrial, and ovarian cancers after twin births

Research output: Contribution to journalArticle

Abstract

The concentrations of endogenous hormones differ between women with twin and singleton births, with a possible influence on the risk of cancer. We used the nationwide Swedish Family-Cancer Database, including 30,409 women with a twin birth, to examine the subsequent risks of breast, endometrial, and ovarian cancers. Relative risks (RRs) were calculated in a log-linear Poisson regression model of person-years as offset. Cancer data were retrieved from the Swedish Cancer Registry; a total of 1010, 210, and 174 women were diagnosed with breast, endometrial, and ovarian cancers respectively, after a twin birth. A significant decrease in the risk of breast cancer was noted among women with a twin birth compared with women with a singleton birth (RR 0.85, 95% confidence interval (CI) 0.74-0.98). The protective effects were observed throughout the intervals after last pregnancy and they were strongest shortly after the last pregnancy in women who delivered a twin birth before 30 years of age. Twin birth did not change the risk of endometrial cancer (1.08, 95% CI 0.79-1.47) but the RR was increased for women with the number of pregnancies > or =4 (1.39, 95% CI 1.11-1.76). The RR for ovarian cancer was 0.95 (95% CI 0.79-1.15). Our study showed that twin births significantly reduced the subsequent risk of breast cancer. However, the associations of twin births with endometrial and ovarian cancers were not substantial.

Details

Authors
External organisations
  • Karolinska Institutet
  • German Cancer Research Centre
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Public Health, Global Health, Social Medicine and Epidemiology

Keywords

  • Adolescent, Adult, Age Factors, Breast Neoplasms/epidemiology, Cohort Studies, Databases, Factual, Endometrial Neoplasms/epidemiology, Female, Gravidity, Humans, Middle Aged, Ovarian Neoplasms/epidemiology, Pregnancy, Pregnancy, Multiple, Risk Factors, Twins
Original languageEnglish
Pages (from-to)703-11
JournalEndocrine-Related Cancer
Volume14
Issue number3
Publication statusPublished - 2007 Sep
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes