San Francisco, CA—Patients who are diagnosed with lung cancer but continue to smoke are at much higher risk for a second primary lung cancer compared with never-smokers or those who have quit smoking, according to the largest analysis of its kind, which was presented at the 2014 American Society for Radiation Oncology meeting.
“This study, which looked at the relationship between smoking history and developing a second lung cancer, adds to the evidence of the harmfulness of cigarette smoking. We presumed that never-smokers would have a lower risk than current smokers, but we were encouraged to find that quitting smoking lowered the risk of second primary lung cancer and quitters had similar overall survival rates as never-smokers,” said lead investigator John Michael Boyle, MD, a radiation oncology resident at Duke University, Durham, NC.
“These findings confirm that smoking cessation is crucial and should be an integral part of patient care for all patients, as well as cancer survivors.”
The study included 1484 patients who underwent surgery for stage I-IIIA non–small-cell lung cancer between 1995 and 2008, including 372 current smokers, 1014 former smokers, and 98 never-smokers. The 5-year incidence of second primary lung cancer was 13% for current smokers, 7% for former smokers, and 0% for never-smokers (P = .03).
During follow-up, only 1 never-smoker developed a second primary lung cancer 7 years later. The risk increased with the number of years of tobacco exposure, equaling an 8% increased risk with every 10 pack-years.
The overall survival (OS) results were quite different among the groups based on the smoking history, Dr Boyle emphasized. “OS was the worst for current smokers. Quitting smoking mitigated increased risk of mortality,” he noted.
The rate of 5-year OS was 39% in current smokers, 46.1% in those who quit >5 years ago, 47.1% in those who quit <5 years ago, and 54.1% in never-smokers.