Abstract P5-08-26: Treatment patterns for breast cancer brain metastasis
Authors: Haraldsson B , Leone JP , McDowell BD , Chrischilles EA 
Published: March 2017

Background: There is sparse data on how mainstay treatments for brain metastasis (BM) are used in clinical practice and whether their usage has changed over time. Our population-based study presents the rates of surgical resection, radiation therapy, and chemotherapy in a large cohort of women with breast cancer BM. Methods: Women diagnosed with breast cancer between 1973 and 2013 were identified from the NCI linkage between the SEER program and Medicare claims data. Identification of BM was via ICD-9 diagnosis codes for secondary CNS malignancy on claims, and was defined as at least one inpatient claim and/or two or more outpatient claims. Treatment was defined as any claim filed with a procedure code for surgical resection of a BM, chemotherapy, and BM-directed radiation therapy. We excluded women without continuous Medicare coverage for a year before to 60 days after their first BM claim and women diagnosed with primary cancer other than breast cancer. Results: The proportion of women receiving treatment after BM claim increased from a low of 50.4% in 1992 to 66.8% in 2013 (p&lt;0.0001). Further analysis of this period revealed rates of surgical resection rose from 7.8% to 11.5%, radiation therapy rose from 39.7% to 54.8%, and chemotherapy rose from 11.9% to 22.2% of women (p&lt;0.002). We used adjusted logistic regression to explore associations between patient/tumor characteristics and treatment. Younger age and fewer comorbidities were associated with increased odds of receiving any of the three treatments. Compared with ER-/PR-, a woman whose index cancer was ER+/PR+ had lower odds of receiving any of the three treatments. Women with extracranial metastasis had greater odds of radiation or chemotherapy and lower odds of resection compared to women with BM only. Receiving any care at an Academic Medical Center (AMC) was associated with greater odds of resection, and lower odds of radiation and chemotherapy.

Table 1 OR; 95% CI RadiationResectionChemotherapyAge: Per 5 years0.8; 0.8-0.90.8; 0.7-0.90.8; 0.7-0.8Race: Black vs. white0.7; 0.6-0.90.6; 0.5-0.90.9; 0.8-1.2Stage: Distant vs. localized1.2; 1.0-1.40.6; 0.5-0.91.1; 0.9-1.3Comorbidities: ≥2 vs. 10.7; 0.6-0.80.6; 0.4-0.80.6; 0.5-0.8ER/PR: +/+ vs. -/-0.5; 0.4-0.50.6; 0.5-0.70.8; 0.7-0.9Lifetime BC burden: ≥2 vs. 10.9; 0.8-1.21.0; 0.8-1.41.0; 0.8-1.3SEER Registry: 2000+ vs. 1973+1.1; 0.9-1.21.2; 0.9-1.40.9; 0.7-1.0Extracranial metastasis: Y vs. N2.9; 2.5-3.40.8; 0.6-0.95.4; 3.8-7.4Year of BM: Per 5 years1.1; 1.1-1.21.0; 0.9-1.11.1; 1.0-1.2Original reason for Medicare enrollment: Disability or ESRD vs. Age0.9; 0.7-1.10.9; 0.6-1.30.6; 0.5-0.8Marital status: Married vs. not1.0; 0.9-1.11.1; 0.9-1.41.2; 1.0-1.3Interval from BC to BM: ≥1 year vs. &lt;1 year0.8; 0.7-0.91.4; 1.0-1.80.8; 0.6-0.9Rurality of patient's home: Less urban vs. Big metro1.3; 1.0-1.61.0; 0.7-1.50.7; 0.5-0.9Care at an AMC: Y vs. N0.7; 0.7-0.81.5; 1.2-1.80.9; 0.7-1.0Chemotherapy in year before BM: Y vs. N1.4; 1.2-1.50.7; 0.6-0.86.0; 5.2-6.9

Conclusions: We found that the proportion of women with breast cancer BM who received treatment has increased over time. Further, logistic regression revealed multiple noteworthy contrasts, including a positive relationship between care at an AMC and surgical resection, while women who received care at an AMC had lower odds of radiation or chemotherapy.

Citation Format: Haraldsson B, Leone JP, McDowell BD, Chrischilles EA. Treatment patterns for breast cancer brain metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-08-26.