Experts cite 'misconceptions' on brain metastases
"Key historical misconceptions" are hindering progress in research and treatment for patients with cancer metastases to the brain, suggests a special article in the July issue of Neurosurgery, official journal of the Congress of Neurological Surgeons. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
Dr. Douglas Kondziolka of NYU Langone Medical Center and coauthors identify some issues that may be standing in the way of optimal clinical management for patients with cancer that has spread to the brain from other sites.
'All Brain Metastases Are Created Equal' - and Other Misconceptions
Brain metastases are an important problem in cancer treatment, but one for which there are relatively few well-designed clinical trials. That partly reflects an "often nihilistic" viewpoint, given that survival is relatively short for many patients with brain metastases.
But a few key studies provide answers to some important questions on the benefits of specific treatments. At a time of rapid progress in cancer care, Dr. Kondziolka and colleagues highlight five misconceptions that, in their view, must be overcome to advance treatment for patients with brain metastases.
The first misconception is assuming that "all histologies are created equal" - that the type of cancer doesn't matter once it has spread to the brain. Historically, studies have included any and all patients with brain metastases. But that may overlook important differences between brain metastases from different types and sites of cancer - for example, lung cancer, breast cancer, or malignant melanoma.
Likewise, there's no basis for the assumption that the number of brain metastases is the sole factor determining patient outcome. Rather, Dr. Kondziolka and coauthors believe the focus should be on the total tumor burden, including the size as well as the number of metastases.
Similarly, some doctors hold the misconception that there's no such thing as a single metastasis - that if one lesion is present, there must be others as well. But that's contrary to strong evidence that treatment for single brain metastases can improve tumor control and patient survival.
Doctors may also believe that treatment with whole-brain radiation therapy (WBRT) inevitably leads to declines in cognitive (intellectual) function. Dr. Kondziolka and coauthors emphasize that, as for any treatment, the risks and benefits of WBRT must be considered for each individual patient. Studies are underway to clarify the cognitive effects of WBRT, with the goal of balancing cognitive functioning with tumor control.
Finally, there's an outdated assumption that since most brain metastases are symptomatic, there's no major benefit of screening tests for early detection. But with increased use of magnetic resonance imaging, metastases are now being detected before they cause any symptoms. Previous studies of larger, symptomatic metastases may not apply to these smaller, asymptomatic lesions.
"Especially in this era of increasingly personalized medicine, one-size-fits-all thinking is improper, especially for a diagnostic entity as wide and varied as brain metastasis," Dr. Kondziolka and coauthors write. Their article includes some recommendations for future trials of brain metastases, including patient-related factors, such as the need for formal measurement of cognitive function; and tumor-related factors, such as studies focusing on a single tumor type and considering the total tumor burden.