UK scientists have discovered that lung cancers can lie dormant for over 20 years before suddenly turning into an aggressive form of the disease, according to a study published in Science today (Thursday). The team studied lung cancers from seven patients -- including smokers, ex-smokers and never smokers. They found that after the first genetic mistakes that cause the cancer, it can exist undetected for many years until new, additional, faults trigger rapid growth of the disease.

During this expansion there is a surge of different genetic faults appearing in separate areas of the tumour. Each distinct section evolves down different paths -- meaning that every part of the tumour is genetically unique.

This research -- jointly funded by Cancer Research UK and the Rosetrees Trust -- highlights the need for better ways to detect the disease earlier. Two-thirds of patients are diagnosed with advanced forms of the disease when treatments are less likely to be successful.

By revealing that lung cancers can lie dormant for many years the researchers hope this study will help improve early detection of the disease.

Study author Professor Charles Swanton, at Cancer Research UK's London Research Institute and the UCL Cancer Institute, said: "Survival from lung cancer remains devastatingly low with many new targeted treatments making a limited impact on the disease. By understanding how it develops we've opened up the disease's evolutionary rule book in the hope that we can start to predict its next steps."

The study also highlighted the role of smoking in the development of lung cancer. Many of the early genetic faults are caused by smoking. But as the disease evolved these became less important with the majority of faults now caused by a new process generating mutations within the tumour controlled by a protein called APOBEC.