Cancer cells may be able to adapt to regional microenvironments in the brain that allow the cancer to progress.
The findings suggest that the location of brain metastasis is not random; cancer cells may be able to adapt to regional microenvironments in the brain, allowing cancer to progress.
Brain metastasis happens when cancer spreads from one part of the body to the brain. According to research, the lifetime incidence of such metastatic brain tumors in cancer patients ranges between 20% and 45%.
A new study from USC Norris Comprehensive Cancer Center, which is part of Keck Medicine of USC, suggests that the region of the brain where cancer spreads is not random, but rather depends on where the cancer originated in the body.
“We discovered that different types of cancer are more likely to show up in specific parts of the brain once they metastasize, indicating the location of tumors follow a distinct pattern,” said Gabriel Zada, MD, a brain and tumor neurosurgeon with Keck Medicine of USC and senior author of the study.
Zada and colleagues investigated the location of brain tumors caused by five common types of cancer: melanoma (a type of skin cancer), lung cancer, breast cancer, renal cancer (kidney cancer), and colorectal cancer. They discovered that lung cancer and melanoma had a higher risk of metastasis in the frontal and temporal lobes (which sit behind the ears). Breast, renal, and colon cancers were more likely to spread to the back of the brain, including the cerebellum and brainstem.
The findings are significant not only because they may predict where particular cancer will spread in the brain, but also because they have implications for how brain tumors grow.
“It may be that cancer cells have the ability to adapt to regional microenvironments in the brain that allow them to colonize and progress, while other areas of the brain are inhospitable to the same cells,” said Josh Neman, the lead author of the study.
The researchers gathered data from patients with metastatic brain cancer who had received stereotactic radiosurgery (SRS), a minimally invasive, targeted form of radiosurgery used to treat brain tumors and other lesions. The SRS enables surgeons to precisely define the coordinates of a brain tumor.
From 1994 to 2015, the researchers used SRS coordinates from 970 patients with approximately 3,200 brain metastatic tumors arising from skin, lung, breast, kidney, or colon cancers treated at USC’s Keck Medical Center. They developed two predictive mathematical models to determine the precise location of brain metastases based on the primary cancer origins.
One model demonstrated that specific regions of the brain were more susceptible to certain types of cancer, while another predicted the likelihood of each cancer metastasizing in specific brain regions. Both models produced roughly the same results in terms of which areas of the brain were most likely to develop cancer-specific tumors.
The study’s findings, according to the researchers, could be useful in the prevention and treatment of brain tumors in the future.
“If we can understand what factors either facilitate or block the process of metastasis, such as certain chemicals or neurotransmitters in the brain, there might be a way to intervene and prevent a cancer from metastasizing in the first place or treat it once it has spread,” Neman said.
“In fact, we are already conducting studies to learn why certain areas of the brain are not receptive to certain cancer cells in hopes of developing better targeted therapies for patients.”
The data from this study is currently being used by Zada and Neman to participate in an international trial involving multiple sites to further study the patterns of brain metastasis based on primary cancer type.
“We are excited to see what new information this larger study will yield in our efforts to better understand and treat this complication of so many common cancers,” said Zada.
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