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Race, ethnicity and risk of second primary contralateral breast cancer in the United States
Journal article   Peer reviewed

Race, ethnicity and risk of second primary contralateral breast cancer in the United States

Gordon P Watt, Esther M John, Elisa V Bandera, Kathleen E Malone, Charles F Lynch, Julie R Palmer, Julia A Knight, Melissa A Troester and Jonine L Bernstein
International journal of cancer, Vol.148(11), pp.2748-2758
06/2021
DOI: 10.1002/ijc.33501
PMCID: PMC9059169
PMID: 33544892
url
https://www.ncbi.nlm.nih.gov/pmc/articles/9059169View
Open Access

Abstract

Breast cancer survivors have a high risk of a second primary contralateral breast cancer (CBC), but there are few studies of CBC risk in racial/ethnic minority populations. We examined whether the incidence and risk factors for CBC differed by race/ethnicity in the United States. Women with a first invasive Stage I-IIB breast cancer diagnosis at ages 20-74 years between 2000 and 2015 in the Surveillance, Epidemiology, and End Results Program (SEER) 18 registries were followed through 2016 for a diagnosis of invasive CBC ≥1 year after the first breast cancer diagnosis. We used cause-specific Cox proportional hazards models to test the association between race/ethnicity and CBC, adjusting for age, hormone receptor status, radiation therapy, chemotherapy and stage at first diagnosis, and evaluated the impact of contralateral prophylactic mastectomy, socioeconomic status, and insurance status on the association. After a median follow-up of 5.9 years, 9247 women (2.0%) were diagnosed with CBC. Relative to non-Hispanic (NH) White women, CBC risk was increased in NH Black women (hazard ratio = 1.44, 95% CI 1.35-1.54) and Hispanic women (1.11, 95% CI 1.02-1.20), with the largest differences among women diagnosed at younger ages. Adjustment for contralateral prophylactic mastectomy, socioeconomic status and health insurance did not explain the associations. Therefore, non-Hispanic Black and Hispanic women have an increased risk of CBC that is not explained by clinical or socioeconomic factors collected in SEER. Large studies of diverse breast cancer survivors with detailed data on treatment delivery and adherence are needed to inform interventions to reduce this disparity.

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