Risk factors for young-onset invasive and in situ breast cancer

Cancer Causes Control. 2015 Dec;26(12):1771-8. doi: 10.1007/s10552-015-0670-9. Epub 2015 Sep 25.


Purpose: Young-onset breast cancers tend to be more aggressive than later-onset tumors and may have different risk factor profiles. Among young-onset cases, there may also be etiologic differences between ductal carcinomas in situ (DCIS) and invasive breast cancer, particularly if some factors promote malignant transformation.

Methods: We evaluated the association between several potential risk factors and young-onset breast cancer in the Two Sister Study (2008-2010), a sister-matched case-control study involving 1,406 women diagnosed with breast cancer before age 50 (1,185 invasive, 221 DCIS) and 1,648 controls.

Results: Older age at menarche, younger age at menopause, premenopausal hysterectomy, early age at first-term pregnancy, obesity, and consumption of alcohol were associated with reduced risk of young-onset breast cancer. These patterns remained when we limited analysis to invasive breast cancers. In general, effect estimates were similar for young-onset invasive breast cancer and DCIS, although the number of DCIS cases was small.

Conclusions: In this sister-matched case-control study of young-onset breast cancer, many of the studied risk factors were associated with young-onset invasive breast cancer. There were few discernable differences in risk factors for young-onset DCIS versus young-onset invasive breast cancer.

Keywords: Breast cancer; Ductal carcinoma in situ; Etiologic heterogeneity; Young-onset breast cancer.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / etiology
  • Carcinoma, Intraductal, Noninfiltrating / epidemiology*
  • Carcinoma, Intraductal, Noninfiltrating / etiology
  • Case-Control Studies
  • Female
  • Humans
  • Menarche / physiology
  • Menopause / physiology
  • Middle Aged
  • Pregnancy
  • Premenopause
  • Risk Factors