Abstract P3-12-10: Age, breast cancer subtype approximation and the risk of the development of brain metastasis in breast cancer patients

Abstract

Abstract Purpose: Biological subtypes and age were well-known risk factors associated with the development of brain metastasis in breast cancer patients. However the impact of each biological subtype in different age group was less discussed. Patient and methods: Patients with invasive ductal carcinoma of breast diagnosed from January 2000 to December 2009 were divided by age of diagnosis into three groups: age below 35, age from 36–59 and age above 60. Four biological subtypes of breast cancer subtype were approximated as luminal A, luminal B, HER2 enriched and triple negative breast cancer by intergrading status of estrogen receptor, progesterone receptor and HER2 and grade. Result: With a median follow-up time of 54.2 months, there were 164 patients (7.3%) among the 2248 enrolled patients developed brain metastasis. Patients with HER2 enriched [hazard ratio (HR) 2.53; 95% confidence interval (CI): 1.57–4.07, p < 0.0001)], triple negative breast cancer (HR 4.42; 95% CI: 2.86–6.85, p < 0.0001) and diagnosed age younger than 35 years-old (HR 2.09; 95% CI: 1.15–3.81, p = 0.016) were strongly associated with higher incidence of brain metastasis. Table 1 showed the important characteritics according to different age group. Furthermore the influence of each biological subtype amoung different age group were investigated. For patient younger than 35 years-old, risk of the developement of brain metastasis was independent to biological subtype (p = 0.507); while the risk of brain metastasis was influenced by biological subtype in older age groups. For patients older than 35, patients with triple negative and HER2 enriched disease had significantly increased risk for brain metastasis compared to luminal A; but for patients with luminal B disease, such incremental risk for the development brain metastasis was only observed in patients older than 60 years-old. Conclusion: Our study found that each biological subtypes of breast cancer had distinct impact on the development of brain metastasis among different age group. Further studies were needed to disclose the biology underneath. Also the findings should be taken into consideration when developing strategy for brain metastasis prevention. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-12-10.