Brain metastases occur when cancer in one part of the body spreads to the brain. The incidence of such metastatic brain tumors in cancer patients ranges from 20% to 45%, studies show.
A new study by the USC Norris Cancer Center, part of the USC Keck Medicine, shows that the region that spreads to the brain may not be random, but rather depends on where the cancer originated in the body.
“We found that different types of cancer are more likely to appear in certain parts of the brain when they metastasize, indicating the location of tumors according to a specific pattern,” said Gabriel Zada, MD, brain and tumor neurosurgeon. USC and senior study author. He is also a member of the USC Norris and director of the USC Brain Tumor Center.
Zada and his colleagues analyzed the location of brain tumors caused by five common types of cancer – melanoma (a type of skin cancer), lung, breast, kidney (kidney) and colorectal. They found that lung cancer and melanoma show a higher likelihood that metastases will be in the frontal and temporal lobes (sitting behind the ears). Cancers of the breast, kidney, and colon had a higher propensity to spread to the back of the brain, such as the cerebellum and brainstem.
The results are important not only because they can predict where a particular cancer may spread in the brain, but also because they are also important for the growth of brain tumors.
“It is possible that cancer cells have the ability to adapt to regional microenvironments in the brain, allowing them to colonize and progress, while other areas of the brain are inhospitable to the same cells,” said Josh Neman, Ph.D. in Surgery and Physiology and Neurology at Keka Medical School. USC, scientific director of the USC Brain Tumor Center and lead author of the study. He is also a member of USC Norris.
To reach their conclusions, the researchers collected data from patients with metastatic brain cancer who were treated with stereotactic radiosurgery (CPS), a minimally invasive, targeted form of radiosurgery used to treat brain tumors and other lesions. SRS allows surgeons to accurately determine tumor coordinates in the brain.
The researchers used CPC coordinates from 970 patients with approximately 3,200 metastatic brain tumors that arose from skin, lung, breast, kidney, or colon cancers treated at Keka USC Medical Center from 1994-2015. They created two predictable mathematical models to analyze the exact location of metastases to the brain based on the primary origin of the cancer.
One model showed that different areas of the brain are relatively susceptible to certain cancers; the other provided the likelihood of metastasis of each cancer to specific areas of the brain. Both models led to approximately identical results as to which areas of the brain are most likely to develop cancer-specific tumors.
Scientists 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 metastasis process, such as certain chemicals or neurotransmitters in the brain, there may be a way to intervene and prevent the cancer from metastasizing in the first place or treat it after it has spread,” Neman said. . “In fact, we’re already doing research to find out why certain areas of the brain aren’t susceptible to certain cancer cells in hopes of developing more targeted therapies for patients.”
Zada and Neman are currently using data from this study to participate in an international study involving several sites to further study the patterns of brain metastases based on the primary type of cancer.
“We are excited to learn what new information this large-scale study will provide in our efforts to better understand and treat this complication of so many common cancers,” Zada said.