A poor network of blood vessels may explain why some people with pancreatic cancer are often resistant to a common chemotherapy treatment, Reuters quoted international researchers as saying today. A study by Cancer Research UK found that pancreatic cancer can spread quickly to a tumour, despite a healthy blood supply, and gave evidence why conventional cancer treatments such as Eli Lilly and Co's Gemzar were often ineffective. The study found that combining cancer treatment Gemzar with Infinity Pharmaceutical's experimental drug IPI-926 made the treatment work better in mice with pancreatic cancer. The findings could lead to better ways to treat one of the most deadly cancers -- one that only three percent of patients survive for five years or more, said David Tuveson, a researcher at Cancer UK's Cambridge Research Institute, who worked on the study. "We're extremely excited by these results as they may help explain the disappointing response that many pancreatic cancer patients receive from chemotherapy drugs," Tuveson said in a statement. "But these are early days and we need to show this approach is safe to use in humans before we can consider adding the new compound to cancer treatments," Tuveson said. Pancreatic cancer is diagnosed in 230,000 people across the world each year, with 7,600 new cases in Britain and 37,000 new cases in the United States, according to Cancer Research UK. It often spreads quickly and is not detected in many people until it is in an advanced stage, when surgical removal is not possible. Using genetically engineered mice that develop pancreatic cancer, the researchers found the tumours in the animals were only sparsely threaded with blood vessels -- something they also saw in humans.