Breast cancer with brain metastases: clinicopathologic features, survival, and paired biomarker analysis

BACKGROUND

The aim of this study was to describe clinicopathologic features of patients with breast cancer brain metastasis (BCBM); to evaluate survival after diagnosis of BCBM; and to compare estrogen receptor (ER), progesterone receptor (PR), and HER2 expression in the paired primary and brain tumors.

MATERIALS AND METHODS

We identified 140 consecutive patients who underwent craniotomy for BCBM (either for diagnostic purpose or with therapeutic intent) at the University of Texas MD Anderson Cancer Center between 2002 and 2009.

RESULTS

Most patients had invasive ductal histology (91%), grade 3 tumors (67%), and positive axillary lymph node (64%). Of the tumors, 56% were ER-negative, 62% were PR-negative, 44% were HER2-positive, and 28% were triple negative (TN). Brain metastasis (BM) was solitary in 51% of patients. Median interval from breast cancer diagnosis to BM was 46 months; median survival after BM was 14.1 months. In the univariate analysis, younger age, solitary brain metastasis, and ER or PR positivity in the breast tumors were associated with longer survival. There was a statistical trend toward increased survival in HER2-positive patients compared with HER2-negative patients (18 vs. 11 months). In the multivariate analysis, predictors for longer survival included younger age, solitary brain lesion, and HER2 positivity in the breast cancer. Biomarkers were evaluated in paired primary and brain tumors in 35 patients for ER status, 34 for PR status, and 36 for HER2 status. Discordant rates were 28% for ER, 20% for PR, and 3% for HER2.

CONCLUSION

Compared with unselected breast cancer patients at the same institution, patients with breast cancer who had brain metastases had a higher proportion of hormone receptor-negative, HER2-positive, and TN tumors. Younger age, solitary brain lesion, and HER2 expression were independent predictors of better survival in patients with BCBM. HER2 status was highly concordant between the paired primary and brain tumors, whereas changes of ER and PR status occurred in a substantial proportion of the patients. These findings are important for making effective treatment decisions for patients with BCBM.

Progress in the biological understanding and management of breast cancer-associated central nervous system metastases

Metastasis to the central nervous system (CNS) is a devastating neurological complication of systemic cancer. Brain metastases from breast cancer have been documented to occur in approximately 10%-16% of cases over the natural course of the disease with leptomeningeal metastases occurring in approximately 2%-5% of cases of breast cancer. CNS metastases among women with breast cancer tend to occur among those who are younger, have larger tumors, and have a more aggressive histological subtype such as the triple negative and HER2-positive subtypes. Treatment of CNS metastases involves various combinations of whole brain radiation therapy, surgery, stereotactic radiosurgery, and chemotherapy. We will discuss the progress made in the treatment and prevention of breast cancer-associated CNS metastases and will delve into the biological underpinnings of CNS metastases including evaluating the role of breast tumor subtype on the incidence, natural history, prognostic outcome, and impact of therapeutic efficacy.

Central nervous system metastases in patients with HER2-positive metastatic breast cancer: incidence, treatment, and survival in patients from registHER

PURPOSE

registHER is a prospective, observational study of 1,023 newly diagnosed HER2-positive metastatic breast cancer (MBC) patients.

EXPERIMENTAL DESIGN

Baseline characteristics of patients with and without central nervous system (CNS) metastases were compared; incidence, time to development, treatment, and survival after CNS metastases were assessed. Associations between treatment after CNS metastases and survival were evaluated.

RESULTS

Of the 1,012 patients who had confirmed HER2-positive tumors, 377 (37.3%) had CNS metastases. Compared with patients with no CNS metastases, those with CNS metastases were younger and more likely to have hormone receptor-negative disease and higher disease burden. Median time to CNS progression among patients without CNS disease at initial MBC diagnosis (n = 302) was 13.3 months. Treatment with trastuzumab, chemotherapy, or surgery after CNS diagnosis was each associated with a statistically significant improvement in median overall survival (OS) following diagnosis of CNS disease (unadjusted analysis: trastuzumab vs. no trastuzumab, 17.5 vs. 3.8 months; chemotherapy vs. no chemotherapy, 16.4 vs. 3.7 months; and surgery vs. no surgery, 20.3 vs. 11.3 months). Although treatment with radiotherapy seemed to prolong median OS (13.9 vs. 8.4 months), the difference was not significant (P = 0.134). Results of multivariable proportional hazards analyses confirmed the independent significant effects of trastuzumab and chemotherapy (HR = 0.33, P < 0.001; HR = 0.64, P = 0.002, respectively). The effects of surgery and radiotherapy did not reach statistical significance (P = 0.062 and P = 0.898, respectively).

CONCLUSIONS

For patients with HER2-positive MBC evaluated in registHER, the use of trastuzumab, chemotherapy, and surgery following CNS metastases were each associated with longer survival.

Brain metastases: the HER2 paradigm

Between 100,000 and 170,000 patients with cancer develop central nervous system (CNS) metastases each year in the U.S., of which approximately 20% carry a primary diagnosis of breast cancer. As a consequence of improvements in systemic therapy, which have allowed patients to live longer with advanced cancer, CNS metastases are emerging as an important sanctuary site, and the incidence may be increasing in patients with particular tumor subtypes. Unless there are improvements in the treatment of CNS disease, a growing proportion of patients may be at risk of experiencing both morbidity and mortality as a result of uncontrolled CNS progression, often at a time when their extra-CNS disease is apparently under control. This article reviews changes in the epidemiology and natural history of women with brain metastases from HER2-positive breast cancer over the last decade and presents the therapeutic challenges and opportunities that have arisen in this setting. First, the apparent increase in CNS disease among women with HER2-positive breast cancer, relative to historical controls, is discussed, followed by consideration of potential causes of this observation. Next, the implications of CNS disease, in terms of prognosis and the potential development of preventive strategies are considered. Finally, new developments in systemic approaches to the treatment of CNS disease, including cytotoxic chemotherapy and targeted therapy, are explored.