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Pregnancy complications and subsequent breast cancer risk in the mother: a Nordic population‐based case–control study

Troisi, Rebecca

International journal of cancer. Volume 143:Issue 8 (2018); pp 1904-1913 -- John Wiley & Sons Inc

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  • Title:
    Pregnancy complications and subsequent breast cancer risk in the mother: a Nordic population‐based case–control study
  • Author: Troisi, Rebecca;
    Gulbech Ording, Anne;
    Grotmol, Tom;
    Glimelius, Ingrid;
    Engeland, Anders;
    Gissler, Mika;
    Trabert, Britton;
    Ekbom, Anders;
    Madanat‐Harjuoja, Laura;
    Sørensen, Henrik Toft;
    Tretli, Steinar;
    Bjørge, Tone
  • Found In: International journal of cancer. Volume 143:Issue 8 (2018); pp 1904-1913
  • Journal Title: International journal of cancer
  • Subjects: Cancer--Periodicals; Cancer--Prevention--Periodicals; breast cancer--Nordic countries--pregnancy--preeclampsia--hypertension; Dewey: 616.994
  • Rights: legaldeposit
  • Publication Details: John Wiley & Sons Inc
  • Abstract: Abstract :

    Certain features of pregnancy are important risk factors for breast cancer, such as protection afforded by young age at first birth. Preeclampsia, a pregnancy complication, is associated with reduced maternal breast cancer risk. However, questions remain regarding causality, biological mechanisms and the relation of other hypertensive conditions to risk. We conducted a population‐based case–control study of breast cancer cases ( n = 116, 196) in parous women identified through linkage of birth and cancer registries in Denmark, Finland, Norway and Sweden (1967–2013), including up to 10 matched controls per case ( n = 1, 147, 192) sampled from the birth registries (complete data were not available on all variables). Odds ratios (ORs) with 95% confidence intervals (CIs) were derived from unconditional logistic regression models including matching factors (country, maternal birth year) and parity. Hypertension diagnosed before pregnancy (OR 0.87; 95% CI 0.78–0.97), gestational hypertension (OR 0.90; 95% CI 0.86–0.93) and preeclampsia (OR 0.91; 95% CI 0.88–0.95) were associated with reduced breast cancer risk. Results remained similar after adjustment for smoking and maternal body mass index before first pregnancy, and were generally similar stratified by parity, age at breast cancer diagnosis, time since first and last birth, sex of the offspring and calendar time. Except for retained placenta (OR 1.14; 95% CI 0.98–1.32), no other pregnancy complication appeared associated with breast cancer risk. The mechanisms mediating the modest risk reductions for history of preeclampsia or hypertension preceding or arising during pregnancy, and possible increased risk with history of retained placenta are unknown and warrant further laboratory, clinical and epidemiological investigation.

    Abstract :

    What's new?

    Preeclampsia, a hypertensive complication in pregnancy, is linked to decreased risk of maternal breast cancer. Little is understood about this association, however, and questions remain about causality and underlying mechanisms. Here, hypertensive conditions before and during pregnancy were analyzed for associations with breast cancer in parous women in Nordic countries. Hypertension diagnosed prior to pregnancy, gestational hypertension and preeclampsia were associated with reduced maternal breast cancer risk. The associations were unaffected by other factors, including smoking, body mass index before pregnancy and age at pregnancy. Further investigation is needed to elucidate the biological mechanisms mediating the observed risk reduction.


  • Identifier: System Number: LDEAvdc_100090726904.0x000001; Journal ISSN: 0020-7136; 10.1002/ijc.31600
  • Publication Date: 2018
  • Physical Description: Electronic
  • Shelfmark(s): ELD Digital store

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