Researchers have identified a gene called SHOX2 whose high expression predicts poor survival in intermediate-grade glioma – a common type of brain cancer. The discovery – if confirmed in further studies – should help doctors decide how aggressive the cancer is and select the best treatment for patients, according to MNT.
The team – from the University of Texas Southwestern Medical Center in Dallas – reports how it identified the prognostic power of SHOX2 in the journal EBioMedicine. There are many types of tumor of the brain and nervous system. They arise in different types of cell and different parts of the brain and spinal cord.
Their signs and symptoms depend on where they start, their size, how fast they grow, and the age of the patient. In the United States, estimates for 2016 suggest there will be nearly 24,000 new cases of cancers of the brain and nervous system, accounting for 1.4 percent of all new cancer cases. Around 34 percent of patients survive 5 years or more after diagnosis.
Gliomas are tumors that start in the glial cells that make up the supportive tissue of the brain. They account for 27 percent of all brain tumors and 80 percent of all malignant tumors. Gliomas can be fast-, intermediate-, or slow-growing. They do not metastasize, or spread to other parts of the body. Patients with gliomas commonly experience weakness, headaches, seizures, or vision changes.
Today’s treatments for glioma are much more sophisticated than they were decades ago, when aggressive therapies did not improve survival or quality of life and often led to significant side effects.
Because we know more about the biology and genetics of gliomas, doctors have a much better chance of selecting treatments that minimize side effects and maximize effectiveness.
SHOX2 expression ‘as potent as current best biomarker’
Depending on the type of glioma, treatment options include surgery, chemotherapy and radiotherapy, and clinical trials. Surgery is common as a first step, while chemotherapy and radiotherapy are more often used to treat high-grade tumors.
An important factor in the decision as to which treatment to give individual patients is knowing their probable survival status. In their paper, the researchers, explain how a type of glioma called “diffuse gliomas” have “highly variable, difficult to predict clinical courses.”
The difficulty in predicting likely survival for diffuse gliomas is further complicated by the fact that classification and grading from tissue analysis varies from observer to observer. However, there is a biomarker – a gene called IDH – whose mutation status is a potent predictor of survival in patients with this type of glioma.
For their study, the researchers analyzed data from several genome-wide datasets that had looked at the survival prognosis of diffuse gliomas, with a focus on the SHOX2 gene. Senior and corresponding author Adi Gazdar, a professor of pathology, explains what they found:
“As an independent biomarker, SHOX2 expression is as potent as the currently best and widely used marker known as IDH mutations.”
He and his colleagues note SHOX2 expression – in combination with IDH mutations or several other biomarkers – helped identify groups of patients with a good prognosis, despite other biomarkers having predicted a poor prognosis. “Our findings are based on analysis of previously published studies. They will have to be confirmed in prospective studies, and their clinical contribution and method of use remain to be determined.” Prof. Adi Gazdar