Terminally ill cancer patients have been "effectively cured" by a game-changing new class of drugs. In one trial, more than half of patients who had just months to live saw deadly tumours shrink or completely disappear.Recently, the results of trials of a number of treatments which harness the body's immune system have been announced at the American Society of Clinical Oncology's annual conference in Chicago.They show promise in the fight against skin cancer and lung disease. But results from trials released on Sunday at the conference showed "spectacular" effects against a multitude of cancers.Experts said the advances suggest terminally ill patients with common cancers - including lung, bowel, ovarian and womb - could in future be cured by the therapies.Senior cancer doctors said the treatment, known as immunotherapy, could radically change the standard treatment for cancer, sparing some sufferers from some toxic effects of chemotherapy.Professor Roy Herbst, chief of medical oncology at Yale Cancer Centre, described the string of results as "huge"."W e are seeing a paradigm shift in the way oncology is being treated ," added Herbst, who said the results suggested the therapy worked best on the cancers that were hardest to treat."The potential for long-term survival, effective cure, is definitely there," he said.Peter Johnson, Professor of Medical Oncology, from Cancer Research UK, said the therapies - which work by "re-educating" the immune system - are one of the greatest breakthroughs in cancer treatment in four decades."Some of the most common types of cancer seem to be treatable with immunotherapy," he said.In one British-led study, 58% of patients with advanced skin cancer saw their tumours reduce significantly when given a new combination of immunotherapy drugs.In more than one in 10 cases, those given the drugs, called nivolumab and ipilimumab, the growths were entirely destroyed.Such patients could expect to live just nine months if given standard treatment. The two-year study of 950 patients has yet to publish survival data but researchers were hopeful that half of the patients would end up "living disease-free".Ipilimumab, the only immunotherapy in use by the National Health Service, costs around £100000 (R1860686) for four treatments. The second drug, nivolumab, is expected to be licensed for use in Europe this summer.The study found their results, when combined, were three times as good as when ipilimumab was given alone.Experts said the new treatments, which use the body's immune system to stall the spread of disease, could soon become the mainstream treatment for a wide range of cancers.Patients who began some of the earliest trials 10 years ago appeared to have been cured, Johnson added. ..