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From London (Ontario) Free Press, 16 September, 2003 TORONTO -- Toronto researchers have identified a key stem cell that may change the treatment of cancerous brain tumours in children. The findings, published yesterday in the journal Cancer Research, may explain why some brain tumours respond to treatment while others don't, said Dr. Peter Dirks, lead investigator on the study, conducted by researchers at the Hospital for Sick Children and the University of Toronto. Until now, researchers have studied every cell in a tumour, not knowing which ones were responsible for its growth, Dirks, a pediatric neurosurgeon at the Hospital for Sick Children, said. "It suggests that if you're treating a patient with a brain tumour, if you wipe out 99 of 100 cells it will shrink, but if you don't get the stem cell it will regrow," he said. "The patient will respond to therapy initially, but then relapse." While the research was conducted on children, the findings also have implications for the treatment of brain tumours in adults, he said. Many current cancer treatments fail because they don't kill the cancer-sustaining stem cells, Dirks noted. Those key stem cells are also responsible for the cancer spreading to other parts of the body, Dirks said. While other cells may break off the tumour and travel within the body, they can't start a new tumour somewhere else. "This is an important thing for pinpointing how tumours grow and spread." The discovery means researchers can focus on finding treatments that will attack those stem cells, Dirks said. Similar key cells have been found in the past few months in breast cancer tumours, Dirks said. Also, similar discoveries in leukemia research have led to remarkable progress in treating that disease in children. Brain tumours are the leading cause of cancer deaths in children and remain difficult to cure despite advances in surgery and drug treatment. In adults, brain tumours are also among the hardest to treat. "In doing what I do, losing babies and young children, it motivated me to do these kinds of experiments," Dirks said. "This is another piece of the puzzle that adds to a wide-ranging theme in cancer biology. It has a lot of important implications and it's now our job to figure out what to do." Dr. Sheila Singh, the paper's lead author, said cancer stem cells are very similar to normal brain stem cells, which suggests the mutations that lead to cancer may originate in the brain's own small number of stem cells. The researchers are now searching for the genes responsible for cancer stem cell growth, which will aid the development of new treatments for brain tumours. The Terry Fox Foundation and the Neurosurgery Research and Education Foundation supported the research. Copyright © The London Free Press 2001,2002,2003 http://www.canoe.ca/NewsStand/LondonFreePress/Today/2003/09/16/193863.html ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn