A study published in the International Journal of Cancer suggests that exposure to a common parasite toxoplasma gondii (T. gondii) may be associated with a risk of glioma brain cancer. T. gondii is most usually found in undercooked meat and can result in the development of cysts in the brain – which researchers now show could have a connection with glioma in adults.
The report, led by James Hodge, JD, MPH and Anna Coghill, PhD, analyzed data from patients in the American Cancer Society's Cancer Prevention Study-II (CPS-II) Nutrition Cohort and the Norwegian Cancer Registry's Janus Serum Bank (Janus). They found an association between the presence of T. gondii antibodies and glioma, meaning that compared to people without cancer, people with glioma are more likely to have the antibodies from the parasite due to a previous infection.
While glioma is quite rare, it is extremely deadly and accounts for 80% of malignant brain tumors. The approximate five-year survival rate of such tumors is only 5%. Understanding why these brain tumors form could be key to reducing risk factors.
While the researchers say that it is possible that reducing exposure to T. gondii could turn out to be an alterable risk factor for gliomas, they are quick to say that their findings are associative, not correlative.
"This does not mean that T. gondii definitely causes glioma in all situations. Some people with glioma have no T. gondii antibodies, and vice versa," comments Hodge. "The findings do suggest that individuals with higher exposure to the T. gondii parasite are more likely to go on to develop glioma," adds Coghill. "However, it should be noted that the absolute risk of being diagnosed with a glioma remains low, and these findings need to be replicated in a larger and more diverse group of individuals."
The investigators hope that further research will validate their findings and provide a path forward for reducing risk of glioma. They write: "…if future studies do replicate these findings, ongoing efforts to reduce exposure to this common pathogen would offer the first tangible opportunity for prevention of this highly aggressive brain tumor."