By Rachel Tompkins A British woman with a rare genetic condition is the first person on a trial aimed at stopping fellow patients getting cancer. Abbi Ritson, 21, has started a five-year scheme to test if diabetes drug metformin can prevent the disease in people with Li-Fraumeni syndrome. One in 5,000 people in the UK have the hereditary disorder – which raises the risk of developing cancer in women by 90% and in men by 70%, according to NHS data. If successful, the trial could save thousands of lives. Abbi said: “I feel grateful to be on this trial. It could mean we could all be taking a drug…