Effect of lifetime lactation on breast cancer risk: A Korean women's cohort study

Soon Young Lee, Miyong T. Kim, Seon Woo Kim, Mi Sook Song, Soo Jin Yoon

Research output: Contribution to journalArticle

Abstract

The objective of our study was to examine the effect of lifetime lactation on breast cancer risk among premenopausal women. The data were from a prospective cohort study with a follow-up period of 6 years in Korea (1995-2000). The cohort was composed of 110,604 premenopausal parous Korean women, aged 20 years and older, who received health insurance from the Korea Medical Insurance Corporation and who had medical evaluations in 1992 and 1994. Multivariate Cox proportional hazard models were tested, controlling for age, age at menarche, number of children, age at first pregnancy, oral contraceptive use, smoking, exercise and obesity. At baseline, 57,440 (51.9%) reported breastfeeding and 4,584 (4.1%) reported breastfeeding more than 24 months. From 1995-2000, 360 incident cases of breast cancer (61.8/100,000 person-years) occurred. Compared to parous women who had no history of lactation, a period of lactation of 13-24 months decreased the risk of breast cancer (RR, 0.7; 95% CI, 0.5-1. 1), and this risk was decreased even further for those who breastfed for more than 24 months (RR, 0.6; 95% CI, 0.3-1.0). There was a clear trend of decreasing breast cancer risk with the duration of lactation (p for trend

Original languageEnglish (US)
Pages (from-to)390-393
Number of pages4
JournalInternational Journal of Cancer
Volume105
Issue number3
DOIs
StatePublished - Jun 20 2003

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Lactation
Cohort Studies
Breast Neoplasms
Korea
Breast Feeding
Menarche
Health Insurance
Oral Contraceptives
Insurance
Proportional Hazards Models
Obesity
Smoking
Prospective Studies
Exercise
Pregnancy

Keywords

  • Breast neoplasm
  • Cohort study
  • Lactation
  • Premenopause

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Effect of lifetime lactation on breast cancer risk : A Korean women's cohort study. / Lee, Soon Young; Kim, Miyong T.; Kim, Seon Woo; Song, Mi Sook; Yoon, Soo Jin.

In: International Journal of Cancer, Vol. 105, No. 3, 20.06.2003, p. 390-393.

Research output: Contribution to journalArticle

Lee, Soon Young ; Kim, Miyong T. ; Kim, Seon Woo ; Song, Mi Sook ; Yoon, Soo Jin. / Effect of lifetime lactation on breast cancer risk : A Korean women's cohort study. In: International Journal of Cancer. 2003 ; Vol. 105, No. 3. pp. 390-393.
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