UNTIL recently, 80 per cent of liver cancer patients were likely to die within months - or even weeks - of diagnosis. Now, Queen Mary Hospital has found that a new treatment technique can prolong patients' median survival rate to one year overall - and as high as three years in those who respond to the therapy. Professor Henry Ngan, head of Hong Kong University's Department of Diagnostic Radiology, said the treatment could not entirely remove the ''death sentence'' that inoperable liver cancer usually gave to sufferers. ''But if you are lucky and respond to the treatment, your prognosis is relatively good,'' he said yesterday at the 35th World Congress of the International Society of Surgery. ''Against the background of this very serious disease, there is some hope for some patients with this treatment. ''But we must not just look at survival for the sake of survival - we must look at quality of life.'' Professor Ngan said under the new treatment, patients had a very good quality of life because it did not bring chemotherapy's side-effects, such as hair loss. Liver cancer is the second most common malignant cancer in Hong Kong. Queen Mary - Hong Kong University's teaching hospital - sees 150 new patients each year. ''Unfortunately, cancer of the liver is very silent,'' Professor Ngan said. ''By the time the tumour presents symptoms, 80 per cent are inoperable.'' Until now, the only option for these patients has been intravenous chemotherapy - but this makes patients very sick and does not prolong survival, he said. Queen Mary Hospital has tried the new treatment on 120 patients in the past 31/2 years. It involves injecting two drugs - Lipiodol, derived from poppy seed oil, and Cisplatin, an anti-cancer drug - into the hepatic artery, which supplies the liver. ''We know this drug Lipiodol is selectively taken up by the tumour,'' he said. ''Because it is mixed, the Lipiodol brings the anti-cancer drug to the tumour, which is slowly released and reaches the tumour in very high concentrations.'' Other parts of the liver are barely affected, he said. Then surgeons inject another substance into the hepatic artery - a type of gel foam cut into tiny pieces - which temporarily blocks the tumour's blood supply. ''We bash the tumour in two ways - first we use the anti-cancer agent to hit it, then we starve it of nutrients,'' he said. Of the 106 patients so far analysed, 54 per cent responded to the treatment, with the best results (71 per cent) among those with tumours of nine centimetres or less. None of those with large tumours of 18 cm or more responded at all. The median survival rate for those who responded was 36 months, while for all 106 patients it was one year, compared to one or two months previously.