Abstract PS01-07: Impact of Race and Ethnicity on Recurrence Risk in Patients with Ductal Carcinoma in Situ Treated with Breast-Conserving Surgery

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Abstract Background: Among women with invasive breast cancer, clinical presentation, tumor biology and survival vary by race and ethnicity. However, the impact of race and ethnicity on clinical presentation and recurrence risk in women with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery (BCS) has not been well studied. We sought to compare rates of recurrence in women with DCIS across racial and ethnic groups and identify factors associated with recurrence. Methods: Patients with DCIS treated with BCS from 1978 to 2016 at a single institution were identified. Patients were grouped and analyzed based on self-reported race and ethnicity as: Asian, Hispanic, non-Hispanic Black (Black), non-Hispanic White (White). Individuals with undefined ethnicity were classified by race, while those lacking both race and ethnicity data were excluded. Clinicopathologic characteristics were compared across racial and ethnic groups. The association of race and ethnicity on recurrence risk was analyzed using Kaplan–Meier methods, competing risk analysis and multivariable analysis. Results: Overall, 4207 cases were included, of which 6% (n= 261) were Asian, 9% (n = 358) Black, 5% (n = 226) Hispanic and 80% (n = 3362) White. Median age was 57 years (IQR 49, 67), 56% received radiotherapy (RT) and 26% received endocrine therapy. Black women with DCIS were older; Asian women were younger (median age: 60 vs 53 respectively, p < 0.001). Black women were more likely to have a clinical presentation (p = 0.006), and Black and Hispanic women were more likely to require ≥3 excisions (p = 0.006). The use of RT was most common among Hispanic women (p = 0.02). At a median follow-up of 8.8 years, 602 (14%) had local recurrence (LR) (315 [52%] DCIS; 284 [47%] invasive and 3 [ < 1%] unknown). The 10-year rate of LR was 15% and was lower in those treated with RT than without (11% vs 20%, respectively; p< 0.0001), despite those receiving RT having more high-risk characteristics. Rates of LR varied significantly by race and ethnicity, with the highest 10-year rate in Black women (25%) compared with Asian (11%), Hispanic (15%) and White (14%) women (p = 0.03). This statistically significant difference persisted among the no RT cohort (10-year rate: 31% [Black], 13% [Asian], 25% [Hispanic], 19% [White], p = 0.043), but did not reach significance in the RT cohort (21% [Black], 9% [Asian], 9% [Hispanic] and 11% [White], p = 0.3). Using competing risk analysis, the risk of invasive recurrence was similar or lower than DCIS recurrence in each racial group with or without RT. After adjusting for other factors on multivariable analysis, there remained a higher risk of LR among Black women (hazard ratio [HR] 1.48, 95% CI 1.12-1.95, p = 0.01). Older age (p < 0.001), radiologic presentation (p = 0.02), margins ≥ 2 mm (p < 0.001), the use of endocrine therapy (p < 0.001) and the use of RT (p < 0.001) were associated with lower rates of LR (Table). Sixteen women (0.4%) developed distant disease, with similar rates among Asian (0%), Black (0.8%), Hispanic (0.9%) and White (0.3%) women (p = 0.2). Conclusion: Compared with Asian, Hispanic and White women, Black women with DCIS had a significantly higher rate of LR after BCS, even after adjusting for known clinicopathologic risk factors. Rates of distant recurrence were low, and similar across racial groups. These higher rates of LR should be considered when making decisions about adjuvant therapy. Table. Factors associated with local recurrence in women with ductal carcinoma in situ treated with breast-conserving surgery. HR, hazard ratio; CI confidence interval; Ref, referent. Citation Format: Natália Polidorio, V. Morgan Jones, Varadan Sevilimedu, Monica Morrow, Kimberly Van Zee, Andrea Barrio. Impact of Race and Ethnicity on Recurrence Risk in Patients with Ductal Carcinoma in Situ Treated with Breast-Conserving Surgery [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS01-07.