Time to Reconsider MRI to Detect Asymptomatic Brain Mets in Breast Cancer?

A fourth of patients with metastatic breast cancer had asymptomatic brain metastases detected within 6 months after enrolling in a study of MRI-based surveillance.

Baseline brain MRI results showed that 14% of 101 patients had asymptomatic brain lesions, with higher rates in patients with triple-negative (TNBC) and HER2-positive versus hormone receptor (HR)-positive/HER2-negative tumors. After follow-up MRI assessment at 6 months, the total incidence had increased to 24% and was similar across breast cancer subtypes, higher than previously recognized.

The findings suggest that reconsideration of current clinical guidelines, which support MRI only for symptomatic brain lesions, might be warranted, reported Kamran Ahmed, MD, of Moffitt Cancer Center in Tampa, Florida, and co-authors in Neuro-Oncology.

“The current [National Comprehensive Cancer Network] guidelines state that brain MRI for breast cancer patients should really only be done when symptoms are present,” Ahmed told MedPage Today. “That differs from the guidelines for non-small cell lung cancer and melanoma, in which routine surveillance brain MRIs are recommended for more advanced disease.

“In our historical data, we and others have noted that because of that [delayed MRI], breast cancer patients, when they present with CNS [central nervous system] disease, tend to have more advanced CNS disease. They more often require whole-brain radiation therapy [WBRT] and more often are diagnosed with leptomeningeal disease.”

Earlier detection of breast cancer brain metastases allows for earlier intervention, including local and systemic therapies, he added. Moreover, management of brain metastases has evolved and improved in recent years.

“We need to conduct larger studies and confirm this at other large cancer centers,” said Ahmed. “But then, potentially, maybe we should be routinely performing brain MRIs in those patients.”

Previous studies have shown that brain metastases occur in 15-30% of patients with stage IV (metastatic) breast cancer. Historically, breast cancer brain metastases portend a poor prognosis. Recent advances in treatment have increased survival in metastatic breast cancer, potentially increasing the number of patients at risk of developing brain metastases, Ahmed and co-authors noted in the introduction to the study. Additionally, some of the newer systemic agents have demonstrated efficacy in brain metastases.

To collect prospective data about asymptomatic breast cancer brain metastases, investigators conducted a single-arm, nonrandomized, phase II trial involving patients with stage IV breast cancer. Eligible patients with HR-positive/HER2-negative breast cancer must have received at least one prior regimen for metastatic disease. Patients with TNBC or HER2-positive disease were eligible regardless of the number of prior lines of therapy. Patients with symptoms of CNS involvement were excluded.

The 101-patient study population comprised 40 patients with HR-positive/HER2-negative breast cancer, 33 with HER2-positive disease, and 28 with TNBC. Median number of prior lines of therapy were four, two, and two, respectively. Baseline MRI scans detected brain lesions in 14% of patients, with a distribution of 18% in TNBC, 15% in HER2-positive, and 10% in HR-positive/HER2-negative patients.

Of the 87 patients eligible for follow-up MRI at 6 months, 66 participated in the follow-up assessment. Following completion of the follow-up MRI, the cumulative incidence of brain metastases was 25% for TNBC, 24% for HER2-positive, and 23% for HR-positive/HER2-negative disease. Ten patients with negative baseline MRI scans developed brain metastases during the 6-month interval between scans.

Among patients with MRI-detected brain metastases, 16 (67%) were treated with focal, stereotactic radiation (SRS), one patient had surgical resection after preoperative SRS, three patients were treated with hippocampal-avoidance WBRT, and two had conventional WBRT. Four patients had leptomeningeal disease, two each with HR-positive/HER2-negative and HER2-positive disease. Nine (38%) patients had a change in systemic therapy following diagnosis of brain metastasis.

Median overall survival since diagnosis of brain metastasis was 19.9 months in all patients, 14.6 months in HR-positive/HER2-negative breast cancer, 9.7 months in TNBC, and not yet reached in patients with HER2-positive breast cancer.

“These results warrant larger prospective trials to refine brain MRI surveillance recommendations for stage IV breast cancer,” the authors stated in their discussion of the findings.

Please enable JavaScript to view the

comments powered by Disqus.