Exposure to T. gondii Linked to Rare Brain Cancer

A new study suggests a link between toxoplasma gondii (T. gondii) infection and the risk of glioma, a type of brain cancer, in adults. T. gondii is a common parasite that is most commonly acquired from undercooked meat, and may lead to the formation of cysts in the brain. The report, appearing in the International Journal of Cancer, found that people who have glioma are more likely to have antibodies to T. gondii (indicating that they have had a previous infection) than a similar group that was cancer free.

More than 40 million men, women, and children in the U.S. carry T. gondii, CDC reports, but very few exhibit symptoms, courtesy of the immune system usually keeping the parasite from causing illness. Nonetheless, toxoplasmosis, the disease caused by T. gondii, is considered to be a leading cause of death attributed to foodborne illness in the U.S., according to CDC.

Study investigators examined the association between T. gondii antibodies measured several years before the cancer was diagnosed and the risk of developing a glioma. The results suggest that reducing exposure to this common foodborne pathogen could provide a modifiable risk factor for highly aggressive brain tumors in adults.

The study authors note that this does not mean that the parasite definitely causes glioma in all situations. Some people with glioma have no T. gondii antibodies, and vice versa, they add. The findings do suggest that individuals with higher exposure to the parasite are more likely to go on to develop glioma; however, 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 authors also note that, if future studies do replicate these findings, ongoing efforts to reduce exposure to this common pathogen could offer the first tangible opportunity for prevention of this highly aggressive brain tumor.”

Although glioma is a relatively rare disease, it is a highly fatal cancer. Globally in 2018, there were an estimated 300,000 incident cases and 241,000 deaths due to brain and other nervous system cancers. The majority (80%) of malignant brain tumors are gliomas, for which the estimated five-year relative survival rate is 5%.