Detectable changes in blood may provide a tell-tale sign of brain cancer nearly five years before a person experiences any symptoms, according to a new study.

Researchers found that changes in immune activity, as seen in blood, were present long before a brain cancer diagnosis. The team examined blood samples from 974 people, half of whom went on to be diagnosed with brain cancer years later. Blood has many components, but they specifically looked at cytokines, which are proteins that help control the immune system and fight disease. Results revealed that people who went on to develop cancer had less cytokine interaction.

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"It's important to identify the early stages of tumor development if we hope to intervene more effectively," lead researcher Judith Schwartzbaum said in a news release. “If you understand those early steps, maybe you can design treatments to block further tumor growth."

The study, published in the journal PLOS ONE, focused on gliomas, which make up a majority of primary brain cancer diagnoses. There are three types of glioma, but all of the tumors begin in the gluey supportive cells (glial cells) around the nerve cells, according to Mayo Clinic.

"There was a clear weakening of (cytokine) interactions in the group who developed brain cancer and it's possible this plays a role in tumor growth and development," Schwartzbaum said.

Furthermore, she notes that this weakened interaction may happen with other types of tumors too, but it’s not quite clear yet. The team also found that a number of the 277 cytokines they looked at played a key role in glioma development, but this needs to confirmed with future research.

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Gliomas are one of the most common types of primary brain tumors. They can be life-threatening depending on their location and how fast they grow. Signs and symptoms vary, but some of the most common include: headache, nausea, vomiting, confusion, memory loss, personality changes, urinary incontinence, vision problems, and seizures. The exact cause is unknown, but those who are older, exposed to radiation, and have a family history of glioma have a higher risk of developing a brain tumor, according to Mayo Clinic.

If a brain tumor is found, there are a range of different treatments your doctor may suggest. Typically, surgery to remove as much of the tumor is the first step, followed by radiation therapy. Other treatments include chemotherapy, targeted drug therapy, and rehabilitation.

Currently there’s 700,000 people in the United States living with a primary brain and central nervous system tumor and nearly 80,000 new cases of primary brain tumors are expected to be diagnosed in 2017, according to the American Brain Tumor Association.

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