Quit smoking effortlessly and you just might have lung cancer, or so a new study seems to suggest.

Barbara Campling, an oncologist at the Thomas Jefferson University in Philadelphia, PA just couldn’t figure out why her lung cancer patients were suddenly quitting smoking without much effort.  Usually, heavy smokers suffer serious withdrawal symptoms including insomnia, dry mouth, and headache.  And yet her patients didn’t seem to have any problems—one of her patients told her that one day he just forgot to smoke and that was the end of his habit.

Campling launched a study that she claims proves that quitting smoking easily may in fact be an early symptom of lung cancer.

“We believe that long-term heavy smokers who quit, especially without difficulty, are at risk for having or developing lung cancer,” the report says in this month’s issue of the Journal of Thoracic Oncology. “We speculate that some lung cancers may produce a factor that blocks or emulates the effects of nicotine.”

Campling led the study at the Philadelphia VA Medical Center between 2004 and 2006.  The study included 115 lung cancer patients that were interviewed in detail about their smoking history and diagnoses.

All of the participants had smoked at least a pack a day for an average of 30 years, and told of their struggles to quit many times.

However, over half of them quit smoking a median of 2.7 years before being diagnosed with lung cancer, and 17 of those quitters did it suddenly and without difficulty.

And even more interesting, 60 participants who kept smoking reduced their tobacco use by at least 50 percent in the year before their diagnosis.

Campling hopes the study will result in additional research to decipher the biological basis for symptom-less withdrawal, which could lead to new methods to help smokers quit.  Heavy smokers that abruptly no longer feel the need to smoke should be tested for lung cancer immediately.

Campling also warns smokers not to get the wrong idea about the results of the study, saying that if you’re a smoker, don’t think that you can “keep smoking so you don’t get cancer.”