Abstract C46: Racial disparities in risk of second breast tumors after ductal carcinoma in situ: A population-based analysis
Authors: Liu Ying , Colditz Graham 
Published: May 2015

Importance: The impact of race and ethnicity on second breast tumors among women with ductal carcinoma in situ (DCIS) has not been well defined.

Objective: To examine racial disparity in DCIS outcomes according to clinical characteristics of tumors.

Design, Setting, and Patients: Data from 18 US Surveillance, Epidemiology and End Results registries included 102,489 women diagnosed with primary unilateral DCIS from 1988 through 2009 (white 73.6%, black 9.7%, Asian 9.0%, and Hispanic 7.7%). Patients undergoing mastectomy (n=31,899) were excluded from the analysis of ipsilateral breast recurrence.

Main Outcomes and Measures: Relative risks (RRs) and their 95% confidence intervals (CI) of ipsilateral breast recurrence and contralateral breast tumors adjusted for pathologic factors, treatment, age at the diagnosis of DCIS, year of diagnosis, and registry.

Results: Among 74,809 women treated with breast conserving surgery or with no surgical treatment, 2,925 (3.9%) developed ipsilateral breast recurrence during a median follow-up of 66 months. Compared with white women, black (RR=1.46; 95% CI, 1.29-1.65) and Hispanic (RR=1.18; 95% CI, 1.03-1.36) women experienced elevated risk of ipsilateral recurrence, which was similar for invasive cancer vs DCIS. A significant increase in risk of ipsilateral recurrence among black women persisted, regardless of age at the diagnosis of DCIS, treatment, tumor grade, tumor size, and histology. Overall, 3,723 (3.6%) of 102,489 women with DCIS developed contralateral breast tumors during a median follow-up of 70 months. The risk for contralateral breast tumors was significantly increased among black (RR=1.21; 95% CI, 1.08-1.36) and Asian (RR=1.16; 95% CI, 1.02-1.31) women compared with white women. Such association depended on type of events (Pheterogeneity&lt;.0001); it was stronger for invasive cancer vs DCIS among black women and for DCIS vs invasive cancer among Asian women. The elevated risk of contralateral breast tumors associated with black race was more obvious among women ≥50 years at the diagnosis of DCIS and those with comedo DCIS; in contrast, a significant increase in risk among Asian women was restricted to those&lt;50 years at the diagnosis of DCIS and those with noncomedo DCIS.

Conclusions and Relevance: Black women with DCIS had disproportionately excess risks of second breast tumors in the ipsilateral and contralateral breasts, which could not be explained by pathologic features and treatment. The elevated risk of ipsilateral recurrence among black and Hispanic women suggests their need for more intensive follow-up and surveillance.

Citation Format: Ying Liu, Graham Colditz. Racial disparities in risk of second breast tumors after ductal carcinoma in situ: A population-based analysis. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr C46. doi:10.1158/1538-7755.DISP13-C46