Abstract P3-06-17: Pattern of distant metastases, including brain, in a population-based cohort of breast cancer patients, by initial stage at diagnosis
Authors: Landis SH , Casso D , Nelson JJ , Wells KE , Oliveria SA , Yood MU 
Published: August 2014

Abstract
Background: Despite advances in medical treatment, 20-30% of women with early stage breast cancer eventually progress to metastatic disease. Metastases to the central nervous system (brain) are a characteristically late complication of disease. As treatment patterns evolve, it is important to understand disease progression (including brain and other distant metastases) as well as time to disease progression, and overall survival. Population based data regarding the development of distant metastases, especially brain, in patients diagnosed with early stage breast cancer are extremely limited, but critical to informing treatment decisions.
Methods: Breast cancer patients newly diagnosed between 1995 to 2007 were identified using the Henry Ford Health System tumor registry, which provides data to the Surveillance, Epidemiology, and End Results Program (SEER). Patients were followed from the date of initial breast cancer diagnosis until the occurrence of the first of the following: 1) death; 2) last known encounter with the health system; or 3) end of the study period (May 31, 2011). Comprehensive data including demographics, occurrence and timing of brain and/or other distant metastases were compiled from medical record review. Tumor characteristics, including HER2 status, and treatment-related medical encounters and procedures were available for a subset of women.
Results: Among the 3,826 women diagnosed with invasive breast cancer, 48% were Stage I at diagnosis, 37% Stage II, 10% Stage III, and 6% Stage IV. Over a median follow-up time of 6.15 years, 625 (16.3%) progressed to distant metastases, of which bone was the most common site, followed by lung and liver.
When examined by initial stage at diagnosis, 4% of Stage I and 15% of Stage II patients went on to develop any distant metastases during the study period; 34% of stage III patients eventually progressed to metastases.
Four percent of all breast cancer patients developed brain metastases. The risk of developing brain metastases was 1% for Stage I, 4% for Stage II, 10% for Stage III, and 23% for Stage IV.
Distribution of any distant metastases and brain metastases among patients diagnosed with invasive breast cancer, Henry Ford Health System, 1995-2007AJCC stage at diagnosisAny distant metastasesBrain metastases N (%)N (%)Stage I (N = 1846)82 (4.4)23 (1.2)Stage II (N = 1395)213 (15.3)57 (4.1)Stage III (N = 384)129 (33.6)38 (9.9)Stage IV (N = 201)201 (100.0)46 (22.9)Total (N = 3826)625 (16.3)164 (4.3)
The median overall survival by stage at initial diagnosis was 15.2 years for Stage I, 12.5 years for Stage II, 6.6 years for Stage III, and 1.8 years for Stage IV breast cancer patients.
Conclusions: We assessed patterns of distant metastases in a population-based cohort of women with invasive breast cancer using medical record review to determine progression. Given the fact that 5% of early stage breast cancer patients (1% of Stage I and 4% of Stage II) developed brain metastases during study follow-up, further study is warranted.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-17.