On 9 October 2014, Reuters carried this news report: Scientists find lung cancer can lie hidden for 20 years

• Lung cancer is the world’s deadliest cancer, killing an estimated 4,300 people a day, according to the World Health Organization.
• The current prognosis for NSCLC is grim, with most patients diagnosed when the disease has already spread and only around 15 percent surviving for at least five years after that.
• Around 85 percent of patients have non-small cell lung cancer (NSCLC).
• To get a clearer understanding of the disease, the two groups of British and American scientists looked at genetic variability in different regions of lung tumors removed during surgery and worked out how genetic faults had developed over time.
• What they found was an extremely long latency period between early mutations and clinical symptoms, which finally appeared after new, additional faults triggered rapid disease growth.
• (What this means is) Lung cancer can lie dormant for more than 20 years before turning deadly.
• In the case of some ex-smokers, the initial genetic faults that started their cancer dated back to the time they were smoking cigarettes two decades earlier.
• On the evolution of lung cancer, scientists in Cancer Research UK reveal how after an initial disease-causing genetic fault — often due to smoking — tumor cells quietly develop numerous new mutations, making different parts of the same tumor genetically unique.
• (What this means is: Not all cancer cells in a lung tumour are the same). This helps explain why a disease that kills more than 1.5 million a year worldwide is so persistent and difficult to treat.
• By the time patients are sick enough to be diagnosed with cancer, their tumors will have developed down multiple evolutionary pathways, making it extremely hard for any one targeted medicine to have an effect. (What this means is: ONE drug cannot kill all the different types of cancer cells in the lung).
• “Previously, we didn’t know how heterogeneous these early-stage lung cancers were.”
• Currently, doctors use computerized tomography (CT) to detect lung cancer — but by the time a nodule is big enough to be spotted it on a scan it may contain a billion genetically diverse cancer cells.

Sources: http://www.reuters.com/article/2014/10/09/us-health-cancer-lung-idUSKCN0HY23Q20141009

http://www.sciencedaily.com/releases/2014/10/141009154007.htm