Smoking's bad, quitting's better, but don't start smoking in the first place if you can help it—because even those who give it up and think they're in the clear after a few years may have an unpleasant surprise lying in wait. Scientists from Cancer Research UK say that lung cancer can remain dormant for more than two decades, then suddenly morph into an aggressive form of the cancer that's difficult to treat. The study published in Science reveals that initial genetic "faults" take place—and many of them are from smoking—but then those anomalies remain unknown for years, until new faults form later on and combine with the foundational faults to trigger a fast-moving growth of the disease. Lung cancer is the No. 1 cancer killer in the US of both men and women, and the survival rate is low compared to other cancers, according to the most recent numbers available from the American Lung Association: While the five-year survival rate for lung cancer that's detected early is 53.5%, that rate plummets to 3.9% if the tumor has spread to other organs.
As the scientists in this study explain, lung cancer is notoriously difficult to treat because when the various genetic faults start cropping up down the line, they're genetically different and appear in various parts of the tumor; targeted treatments in one part of the tumor, therefore, aren't effective at wiping out cancer in other parts, notes Cancer Research UK. This study was admittedly small—researchers examined just seven patients who were smokers, ex-smokers, or non-smokers—but these sobering statistics and treatment challenges are lighting a fire under scientists to conduct more research like this that may eventually enable earlier intervention. "If we can nip the disease in the bud and treat it before it has started traveling down different evolutionary routes, we could make a real difference in helping more people survive the disease," Cancer Research UK's chief scientist says. (Nearly 10% of cancer survivors keep on smoking.)