31/08/2010

Individual Prognosis through Genetic Analysis of Brain Tumour Cells

Analysis of alterations in the genetic material of ependymomas, a relatively common type of brain tumour, enables physicians to predict disease progression more precisely. A research group headed by Dr. Stefan Pfister of the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) and Heidelberg University Hospitals has presented their results.

"This finding is a step forward for the benefit of the patient," says Dr. Stefan Pfister, who is pleased about the results jointly with his colleagues, Professor Andrey Korshunov and Dr. Hendrik Witt of DKFZ and Heidelberg University Hospitals. "Now we can develop new and individual treatment approaches for patients with biologically different ependymomas. We can use the specific alterations in the chromosomes as markers which indicate the degree of intensity needed for treating different patient groups."

The researchers studied tumour material of 292 patients suffering from ependymoma, the second most frequent brain tumour in children. The study included only patients with established WHO tumour grades II and III. However, this ependymoma classification hardly provides any indication of how difficult treatment of the disease will be.

Surgery is the first form of treatment for ependymoma patients. It may be difficult to remove the tumour completely, since ependymomas frequently grow close to the brain stem or other vital brain structures. The traditional postoperative treatment for younger children is chemotherapy, while older children receive radiotherapy. The age limit in the study presented was four years, because detrimental late effects of irradiation on the developing brain in very young children were feared.

The researchers studied the tumour cells removed, comparing them with healthy cells. They found characteristic alterations in the chromosomes, the carriers of genetic material, of the brain tumour cells. They regularly found gains or losses of whole chromosomes or chromosome regions. The investigators proceeded to compare the prognostic value of these aberrations with respect to survival with known prognostic factors. These include recurrence of disease, age at diagnosis, gender, position of tumour in the brain, WHO tumour grade and whether or not it was possible to remove the tumour completely by surgery.

The researchers found out that, besides a young age at diagnosis, the knowledge of individual alterations in the genetic material of tumour cells facilitates very accurate predictions about disease progression. Thus, gains on the long arm of chromosome 1 as well as the loss of tumour-suppressing genes are associated with a rather poor response to treatment so that it is important to find new or additional treatment options for these patients. On the other hand, complete loss of chromosome 6 or gains on chromosomes 9, 15 or 18 were associated with longer survival of the patients. Further investigations will show whether doctors may spare these patients some stressful treatments.

Fonte: Helmholtz Association of German Research Centres