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A CPS-II Nutrition Cohort Study: Researchers showed that a parasite most commonly found in undercooked meat may lead to certain brain cancers.
Researcher: James Hodge, JD, MPH
Institution: American Cancer Society
Area of Focus: Population Science
“Our findings suggest that infection with the parasite Toxoplasma gondii may play a role in development of glioma. If confirmed by future research, this would represent a breakthrough in finding a modifiable risk factor for this particularly insidious form of brain cancer.”
The Challenge: Brain tumors are rare, and there are many different types. The most common brain tumors are gliomas, and they tend to have a low 5-year survival rate. The causes of brain tumors, including gliomas, remain largely unknown. Few studies have been able to identify modifiable risk factors, but some suggest a potential association between certain infections and increased risk. One of those infections is caused by the microscopic parasite Toxoplasma gondii (T gondii).
T gondii is a common parasite that infects warm-blooded animals, including humans. Infections most often occur from:
Even though many animals and people around the world may be infected with T gondii, most people with healthy immune systems aren’t affected by it and don’t have any symptoms or illness.
T gondii infections in the brain have, however, been linked with changes in cognitive function and behavioral disorders in both animals and humans. Earlier studies with groups of people have also suggested a link between gliomas and T gondii infections, but studies looking at individuals are lacking.
The Research: James Hodge, JD, MPH, and his American Cancer Society (ACS) colleagues recently led the first prospective cohort study to provide evidence of an association between T gondii infection and the risk of glioma brain tumors.
He and his team analyzed blood samples given by participants in the ACS Cancer Prevention Study-II Nutrition Study when they were cancer free. They also studied samples from a Norwegian biorepository in collaboration with researchers from the H. Lee Moffitt Cancer Center and Research Institute in Tampa. To identify those infected with the parasite, they looked for two antibodies to T gondii, which would have occurred in response to the presence of the parasite.
During the time the Nutrition Cohort was followed, 50 CPS-II Nutrition Study participants were diagnosed with gliomas, and 323 people were diagnosed in the Norwegian cohort.
When Hodge and his team compared glioma cases to cancer free participants, they found that those who had T gondii antibodies in their blood were more likely to develop a glioma in the 13 years after the blood was collected.
To prevent infection with T gondii, follow these tips from the Centers for Disease Control (CDC):
To confirm the possible role of T gondii infection in causing gliomas, more studies are needed with larger numbers of people with gliomas.
Why Does It Matter? If Hodge’s results are replicated in future studies, we could be a step closer toward identifying a modifiable risk factor for glioma.