Gliomas – the most common form of brain cancer – are rarely caught early enough to successfully treat.
New research looking at the links between brain cancer and the immune system may soon make it possible to detect these cancers much earlier.
Around 80 percent of brain cancer diagnoses are gliomas.
These tumors develop from glial cells, which act as a support system for nerve cells in the brain.
Glioblastoma, the most common type of glioma, occurs in two to three people in every 100,000. The average survival time is14 months.
Experts say these tumors “result in more years of life lost” than any other tumors.
Symptoms associated with glioma vary depending on the position of the tumor, but they often include headache, confusion, memory and balance problems, personality changes, and difficulties with speech.
Because the symptoms vary from individual to individual and are similar to those of other conditions, diagnoses of gliomas often come too late. On average, a diagnosis is made around three months after the onset of symptoms.
Why gliomas develop in some individuals and not others is still not clear.
Currently, the only known risk factors are exposure to high doses of ionizing radiation and certain rare genetic mutations.
Because of this, studies into why and how the disease appears and progresses are vital.
The immune system and gliomas
A study, published this week in the journal PLOS One, focuses on the relationship between chemical signals from the immune system and the development of brain cancer.
Judith Schwartzbaum, an associate professor of epidemiology and a member of The Ohio State University’s Comprehensive Cancer Center, headed up the study.
“It's important to identify the early stages of tumor development if we hope to intervene more effectively,” said Schwartzbaum. “If you understand those early steps, maybe you can design treatments to block further tumor growth.”
Schwartzbaum investigated blood samples of 974 people, taken from Norway’s Janus Serum Bank. Half of the individuals went on to develop brain cancer. The others acted as a control group.
Earlier investigations, including some by Schwartzbaum, have uncovered a relationship between allergies, the immune system, and brain cancer. It appears that allergies may protect against the development of brain cancer.
In fact, there is evidence that allergies can reduce the risk of glioma by almost 40 percent.
Studies have shown that brain cancer risk is lower in people with higher levels of immunoglobulin E – a protein released by the immune system during an allergic reaction – in the blood.
Because of this link, Schwartzbaum and her team were particularly interested in cytokines, which are immune proteins that communicate with other cells and help to orchestrate the immune response.
The role of cytokines
For the current study, Schwartzbaum assessed 277 cytokines.
She found that, in the blood of people who went on to develop brain cancer, there was less cytokine interaction.
Schwartzbaum explains, “There was a clear weakening of those interactions in the group who developed brain cancer, and it's possible this plays a role in tumor growth and development.”
These changes could be measured five years before the formation of the brain tumor.
The role of cytokines in cancer is, to date, poorly understood.
In some circumstances, they can help to fight tumor growth, but in others cytokines assist the growth of a tumor by suppressing the immune system.
In the current study, the researchers found a number of specific cytokines that appear to play a particularly significant role in the formation of gliomas. These chemicals will be explored in further studies.
Although a routine blood test for brain cancer will not be a practical solution that could be rolled out across the population, the findings are important.
Catching tumors earlier in their progression means that treatment is more likely to be successful.
These results might also have a wider-ranging importance, as Schwarzbaum adds, “It's possible this could also happen with other tumors – that this is a general sign of tumor development.”
Further work will be needed to sure up the discoveries, but they mark another interesting milestone in the slow war of attrition against cancer of all types.