Racial/ethnic differences in postmenopausal breast cancer risk by hormone receptor status: The multiethnic cohort study

Int J Cancer. 2022 Jan 15;150(2):221-231. doi: 10.1002/ijc.33795. Epub 2021 Sep 16.


There are racial/ethnic differences in the incidence of hormone receptor positive and negative breast cancer. To understand why these differences exist, we investigated associations between hormone-related factors and breast cancer risk by race/ethnicity in the Multiethnic Cohort (MEC) Study. Among 81 511 MEC participants (Native Hawaiian, Japanese American, Latina, African American and White women), 3806 estrogen receptor positive (ER+) and 828 ER- incident invasive breast cancers were diagnosed during a median of 21 years of follow-up. We used Cox proportional hazards regression models to calculate associations between race/ethnicity and breast cancer risk, and associations between hormone-related factors and breast cancer risk by race/ethnicity. Relative to White women, ER+ breast cancer risk was higher in Native Hawaiians and lower in Latinas and African Americans; ER- disease risk was higher in African Americans. We observed interaction with race/ethnicity in associations between oral contraceptive use (OC; Pint .03) and body mass index (BMI; Pint .05) with ER+ disease risk; ever versus never OC use increased risk only in Latinas and positive associations for obese versus lean BMI were strongest in Japanese Americans. For ER- disease risk, associations for OC use, particularly duration of use, were strongest for African Americans (Pint .04). Our study shows that associations of OC use and obesity with ER+ and ER- breast cancer risk differ by race/ethnicity, but established risk factors do not fully explain racial/ethnic differences in risk. Further studies are needed to identify factors to explain observed racial/ethnic differences in breast cancer incidence.

Keywords: breast cancer; estrogen receptor; hormone-related risk factors; race/ethnicity; risk.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Breast Neoplasms / etiology*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Ethnicity / statistics & numerical data*
  • Female
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Postmenopause / ethnology*
  • Prognosis
  • Prospective Studies
  • Receptors, Estrogen / metabolism*
  • Receptors, Progesterone / metabolism*


  • Receptors, Estrogen
  • Receptors, Progesterone