A provocative, though small, study suggests that the very act of quitting smoking may be a symptom of not-yet-diagnosed lung cancer.
That's the curious conclusion reached by a team of researchers led by Barbara Campling at Thomas Jefferson University in Philadelphia when they surveyed 115 lung cancer patients, all of them current or former smokers, at the Philadelphia Veterans Affairs Medical Center. The team asked when the patients had stopped smoking relative to their diagnosis and onset of symptoms and how difficult or easy it had been for them to quit. They also used a standard tool called the Fagerstrom Test for Nicotine Dependence to calculate how addicted they had been to nicotine at the peak of their smoking habit.
Campling and her team, whose work appears in the March issue of the Journal of Thoracic Oncology, undertook the study on a hunch: They had observed that many of their own lung-cancer patients had quit smoking before they were diagnosed, often without consciously deciding to do so. The team was aware of the common wisdom that holds that people typically quit smoking in response to the appearance of symptoms suggestive of lung cancer. But they weren't convinced that was really how things work.
Their study appears to bear out their hunches. They learned that 55 of the 115 patients had quit smoking before being diagnosed, all but six of them before any lung cancer symptoms appeared. Of those who quit, 31 percent reported they'd done so with ease. But not because they had never been addicted: Their levels of addiction had been the same, when they were smoking the most, as those who hadn't quit.
Their research also teased out the fact that people didn't quit smoking just because they'd lost the taste for it. Instead, the authors suggest, the presence of a lung-cancer tumor may somehow block the body's uptake of, or desire for, nicotine; perhaps, they surmise, such tumors may secrete a chemical that makes that happen.
They acknowledge that their work has limitations, among them the small sample size and the fact that the data was self-reported and after the fact. Still, they believe they're on to something -- something that should be looked into further, in a larger study of different design.
Campling and team clearly have grappled with the implications of their work and the potential for it to be misunderstood as encouragement for people to keep smoking. Though they note that their findings build on previous data showing that people who quit smoking are more likely to be diagnosed with lung cancer in the time immediately after they quit than those who keep smoking, they insist that their conclusions are not to be read as suggesting that people who smoke keep doing so:
We believe that long-term heavy smokers who quit, especially without difficulty, are at risk for having or developing lung cancer. Our study could be dangerously misinterpreted to suggest that those who have smoked heavily for most of their lives might be better off to continue smoking. This is clearly not the case. All smokers, especially heavy smokers, must be strongly encouraged to stop.
So what are we to take away from this? The study concludes that if we come to understand spontaneous smoking cessation as a potential warning sign that lung cancer may be afoot, that could lead to earlier diagnosis -- one of the best, but most elusive, weapons against that deadly disease.