Lung cancers can lie dormant for more than 20 years before suddenly turning into an aggressive form of the disease, according to a new study.
The team from Cancer Research United Kingdom (UK) studied lung cancers from seven patients, which included 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 mutations trigger rapid growth of the disease.
During this expansion, a surge of different genetic mutations appears in separate areas of the tumor. Each distinct section evolves down different paths, which means that every part of the tumor is genetically unique.
This research, which was 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 have advanced forms of the disease at diagnosis, which is 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. The research was published in Science (2014; doi:10.1126/science.1253462).
“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,” said study author Professor Charles Swanton, MD, PhD, at Cancer Research UK’s London Research Institute and the University College London Cancer Institute
The study also highlighted the role of smoking in the development of lung cancer. Many of the early genetic mutations are caused by smoking. But as the disease evolves, these became less important, and the majority of mutations are caused by a new process generating mutations within the tumor controlled by a protein called APOBEC.
The wide variety of mutations found within lung cancers explains why targeted treatments have had limited success. Attacking a particular genetic mistake identified by a biopsy in lung cancer will only be effective against those parts of the tumor with that mutation, leaving other areas to thrive and take over.