Abstract P1-15-04: Outcome of small (≤1 cm), node-negative breast cancer

Abstract

Abstract Background: Screening mammogram has resulted in increased diagnosis of very small breast cancers, especially less than 1 cm node negative. These small tumors have excellent prognosis with cancer-specific survival rates as high as 90% to 95%. This study evaluates outcome in different subtypes of very early breast cancer in a national population database. Method: Patients with stage I breast cancer, tumor ≤ 1cm with negative nodes (T1aN0 (<0.5cm), T1bN0 (≥ 0.5cm to ≤ 1cm) diagnosed between 2006 and 2011 were identified in the SEER database. We excluded patients with missing biomarker information. Treatment outcome and prognostic factors for disease-specific survival (DSS) and overall survival (OS) were evaluated. Results: We identified 70,543 cases and included 54,796 patients with stage T1aN0M0 and T1bN0M0 in the final analysis. The mean age was 62.09 yrs. (CI 95% 62.2-61.99), 84% are white, 7% black and 7% others.89% had ER positive tumor, 11% ER negative and 3% had Her 2 positive tumors.71% of patients had T1b (≤ 1cm). The 5-year disease specific survival (DSS) and overall survival (OS) for patients with stage T1aN0, T1bN0 was 98.7% and 93.7%, respectively. Estrogen receptor (ER) positive tumors were associated with improved 5-yr DSS 99% vs. 96% in ER negative (p<0.0001) and OS in ER positive 94% vs. 92%( p<0.0001). Among white patients 5-yr DSS was 98.8% and OS was 93.7% while 5yr-DSS was 94%, OS 91.5% among black vs. 5-yr DSS 99% and OS 96.3% in others (Asian or Pacific Islanders, AI), (p<0.0001). Tumor subtype was not associated with significant difference in outcome but T1a tumor was associated with OS 94.5% vs. 93.4% with T1b tumors (p<0.0001) On cox model analysis factors which correlated with prolonged DSS and OS are race (p<0.0001), older age (p<0.0001), ER positivity (p<0.0001) and tumor less than 5mm (p=0.0006). Conclusions: Very early breast cancer is associated with excellent outcome but has some heterogeneity. Nonwhite/Non Black race was associated with better survival compared to white and black patients. ER positive tumors, and older age were also associated with better outcome. This data while reassuring also brings into question the overtreatment of this disease subset. One of the limitations of this dataset is lack of details of systemic therapy administered. Conventional prognostic factors are not sufficient to risk stratify very early breast cancer and molecular profiling may help identify patients who will need adjuvant treatment. Citation Format: Muzaffar M, Namireddy P, Naqash R, Wong J, Vohra N. Outcome of small (≤1 cm), node-negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-15-04.