'I have great confidence that by the end of the decade we'll know in vast detail how cancer cells arise,'says microbiologist Robert Weinberg, an expert on cancer. 'But,' he cautions, 'some people have the idea that once one understands the causes, the cure will rapidly follow. Consider Pasteur, he discovered the causes of many kinds of infections, but it was 50 or 60 years before cures were available.' This year, 50% of the 910,000 people who suffer from cancer will survive at least five years. In the year 2000, the National Cancer Institute estimates, that figure will be 75%. For some skin cancers, the five-year survival rate is as high as 90%. But other survival statistics are still discouraging – 13% for lung cancer, and 2% for cancer of the pancreas.