THURSDAY, Jan. 21 (HealthDay News) -- Quitting smoking after a diagnosis of early stage lung cancer doubles the odds that a patient will live another five years, a new study finds.
"The results are quite dramatic. I don't think anybody would have expected such a dramatic difference. It's incredible," said Dr. Norman Edelman, chief medical officer for the American Lung Association. "The important caveat is that this is early lung cancer."
Early stage lung malignancies can have cure rates of 50 percent to 60 percent, Edelman noted. The tragedy is that very few lung cancers (perhaps 20 percent, the authors stated) are diagnosed at this early stage.
The new findings are published in the Jan. 21 online edition of BMJ.
According to an accompanying journal editorial, fewer than one-third of all patients with lung cancer are still alive just one year after diagnosis.
Of course, the best way to prevent lung cancer is to never smoke, or to quit if you do smoke. People who quit smoking have a dramatically lower incidence of being diagnosed with lung cancer over the life span, experts note.
But it's been less clear how quitting smoking might affect patient prognosis after a diagnosis has already been handed down, the study authors said.
To find out, the British researchers pored over data from 10 prior observational studies looking at the impact of quitting smoking post-diagnosis.
"We used meta-analysis to summarize their findings," said study lead author, Amanda Parsons, a Ph.D. candidate at the U.K. Centre for Tobacco Control Studies at the University of Birmingham College of Medicine and Dentistry. "Quitting smoking was associated with around double the chance of surviving at any time point compared to people who continued to smoke."
Only 29 to 33 percent of early stage lung cancer patients who kept smoking survived for five years, while 63 to 70 percent of patients who quit survived that long, Parsons stated.
The survival seemed to come from a lower likelihood of tumor recurrence, not from heart/lung improvements, the researchers said.
All the patients were early stage and had been treated with either surgery, chemotherapy or radiation so, Parsons added, "the results can only be applied to this group of lung cancer patients. This work does not tell us anything about the benefits of quitting smoking if you have advanced disease."
And because all of the studies included in this analysis were observational in nature, it's not certain yet whether quitting smoking actually caused the decline in deaths.
Still, the findings beg the question of whether smoking cessation counseling should be routinely offered to people diagnosed with lung cancer.
According to Parsons, "smoking cessation support is not routinely offered to patients with lung cancer although some hospitals may offer this support." That's in Britain, Edelman noted, and the odds of there being any consistency in this area is even less likely in the U.S., which has no overarching health care system.
"Certainly the American Lung Association pushes smoking cessation for everybody. We say over and over again -- it's never too late to quit. There's good evidence that you can get benefits if you're 70 years old," he said.
Find out more on the benefits of quitting smoking at the U.S. National Cancer Institute.
SOURCES: Amanda Parsons, Ph.D. candidate and research fellow, U.K. Centre for Tobacco Control Studies, University of Birmingham College of Medicine and Dentistry, Birmingham, U.K.; Norman Edelman, M.D., chief medical officer, American Lung Association; Jan. 21, 2010, BMJ, online