The number of patients with malignant brain tumours is increasing, with 200 to 250 cases discovered each year, researchers announced yesterday. There were 191 cases discovered in 1993 and 193 in 1995. Warning that 90 per cent of cases were incurable, Professor Poon Wai-sang, head of the neurosurgical unit at the Chinese University's Department of Surgery, said the cause was unknown. 'The factors contributing to the formation of brain tumours are complex and genetic,' he said, adding that bad injuries and radiation were two of the triggers. Professor Poon said 40 per cent of brain tumours in Hong Kong were of the glioma type, which occurred in the central part of the brain and were malignant in most cases. 'Most of these patients will die. All we can do is to try to extend their lifespan. In the worst cases, the patients die within a year.' The earlier the tumour was discovered, the greater the chance of recovery. 'The most obvious symptom is a headache. However, only one or two people out of every 100 with a headache may have problems relating to the brain,' Professor Poon said. He warned that if a healthy person had a sudden headache, even after a good sleep, and vomited, he or she should consult a doctor. 'At an early stage, the tumour can be removed by operation more easily,' Professor Poon said. The Chinese University has set up a research centre with hospitals in Beijing and Shanghai, hoping to gather more information on the genetics of brain tumour formation.