Depending on Origin, Brain Metastasis Have Distinct Geographic Spread

A new study from USC Norris Comprehensive Cancer Center suggests that the location of brain metastasis is not random but rather is dependent 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, senior author of a study published recently in the Journal of Neurosurgery.

Zada and colleagues analyzed the location of brain tumors caused by five common types of cancer—melanoma, lung, breast, renal, and colorectal. They discovered that lung cancer and melanoma showed a higher likelihood for the metastasis to be at the frontal and temporal lobes. Breast, renal, and colon cancers had a higher propensity to spread to the back of the brain, such as the cerebellum and brainstem.

The findings are important not only because they may predict where a specific cancer may spread in the brain, but because they also 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 lead author of the study.

To reach their conclusions, the researchers collected data from patients with metastatic brain cancer treated using stereotactic radiosurgery (SRS). The researchers used the SRS coordinates from 970 patients with approximately 3,200 brain metastatic tumors arising from skin, lung, breast, kidney, or colon cancers. They created two predictive mathematical models to analyze the exact locations of brain metastases based on the primary cancer origins.

One model showed that distinct regions of the brain were relatively susceptible to certain types of cancer; another provided the probability of each cancer metastasizing in certain brain regions. Both models resulted in the approximate same results as to which areas of the brain were most likely to develop cancer-specific tumors.

The researchers believe the results of the study could be useful in the eventual prevention and treatment of brain tumors.

“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.”