Study of the Week: Parasite Becomes a Glioma Risk Factor

Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.

If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.

 

This week’s study is…

Toxoplasma gondii infection and the risk of adult glioma in two prospective studies

We previously published a story about this research in a story titled “A Common Parasite With an Uncommon Name: Toxoplasma gondii is Associated with Brain Cancer,” which can be found here. The study was originally published in the medical journal International Journal of Cancer. You can view the abstract of it here.

This study was directed and led by the American Cancer Society’s James Hodge, an epidemiologist, and Dr. Anna Coghill of the Moffitt Cancer Center and Research Institute.

What Happened?

Prior research has suggested that there is a connection between infection with Toxoplasma gondii (T. gondii) and the appearance of gliomas, which are brain tumors that include the vast majority of malignant primary brain cancers. The most notorious form of glioma is glioblastoma, which is the most aggressive and common type of primary brain tumor in adults. However, there has never been a clearly established association. This study aimed to examine this link by comparing the presence of T. gondii antibodies with the risk of glioma.

This study drew on cohorts of patients from the American Cancer Society’s Cancer Prevention Study‐II Nutrition Cohort and the Norwegian Cancer Registry’s Janus Serum Bank. Data from a total of 360 patients was used for this study. The method involved the analysis of blood samples from patients before their cancer diagnosis; the scientists were looking for the presence of antibodies for two different T. gondii surface antigens.

The presence of these antibodies would indicate that these patients had been infected with the organism in the past. The researchers found that prior infection appeared to increase the risk of cancer when compared to the placebo groups. This effect was found in both cohorts despite significant age differences; the Janus cohort had an average age of 40 years and the other was around 70 years. The effect was most significant in patients with high levels of sag-1 antigen antibodies.

About Glioma

Gliomas are brain tumors which originate in the glial cells, which are present in the brain and spine. These types of tumor comprise 80 percent of malignant brain tumors, and they are very difficult to treat. This makes them highly lethal. Certain genetic mutations, hereditary disorders, infection with cytomegalovirus, and a diet high in cured foods may be risk factors for glioma, but the direct cause is unknown in most cases. Symptoms can include personality changes, headaches, memory loss, seizures, vomiting, and nausea; patients may lose consciousness in late stages. Treatment approaches include anticonvulsants, steroids, chemotherapy, radiation, and surgery. While a small number of patients can survive for several years, treatment is often ineffective, with the tumor relapsing quickly. Five year survival rate is only around five percent. To learn more about gliomas, click here

About Toxoplasma gondii

Toxoplasma gondii is a parasitic protozoan that is capable of infecting basically all warm-blooded animals. It targets neural tissue and can cause cysts to appear in the brain; infection with T. gondii is called toxoplasmosis. It is considered one of the most common parasites in the developed world, and studies suggest that as much as 50 percent of the human population has been exposed to it. In healthy adults, it usually doesn’t cause symptoms, the mild-flu like reactions can occur. Toxoplasmosis generally only affects people with weakened immune systems, such as HIV/AIDs patients, newborns, and others. These cases are serious and may be fatal. Some studies have suggested that infection with T. gondii may cause subtle changes to behavior and personality in humans. Click here to learn more.

Why Does it Matter?

The findings from this study appear to reveal that T. gondii infection is a likely risk factor for the development of glioma tumors. However, the researchers point out that it is not always a direct cause. Some people with glioma do not have the antibodies. Meanwhile, there are others who may have antibodies but never get glioma. Overall, the risk for people with T. gondii antibodies to get glioma is still low overall; but their risk is still slightly increased. Ultimately, further case studies conducted on a larger scale will be critical to helping confirm this connection.

The authors concluded their research with this:

“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.”

With the treatment options for glioma being so ineffective, preventative measures may be the best hope for bringing down the number of cases.

Check back the Monday of each week for the next installment in this series.

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