Never-Smokers and Ever-Smokers Have Similar Risk of Second Primary Lung Cancer

Lung cancer survivors who have never smoked have a similar risk of developing a second primary lung cancer as survivors with a history of smoking, according to research published in JAMA Network Open.

This similar risk exists despite ever-smokers being much more likely to develop an initial primary lung cancer than never-smokers, researchers reported.

The researchers analyzed data from more than 200,000 patients who were enrolled in the Multiethnic Cohort Study during 1993-1996 and were followed through 2017 for the development of initial primary lung cancer and second primary lung cancer.

The cohort included 7161 patients who had initial primary lung cancer. The patients’ mean age at enrollment was 63.6 years, 56.3% were men, and 88.1% (n=6315) had a smoking history.

The 10-year cumulative incidence of initial primary lung cancer was 7 times higher among ever-smokers than among never-smokers, at 2.40% and 0.34%, respectively.

Among patients who had been diagnosed with initial primary lung cancer, 163 (2.28%) had second primary lung cancer. The 10-year cumulative incidence of second primary lung cancer was not significantly different according to smoking status. It was 2.84% for never-smokers and 2.72% for ever-smokers.

The second primary lung cancer incidence among patients with initial primary lung cancer (962.57 per 100,000 person-years) was more than 5-fold higher than the initial primary lung cancer incidence in the entire cohort (175.88 per 100,000 person-years). The standardized incidence ratio (ratio of second primary lung cancer to initial primary lung cancer) was 5.47 (95% CI, 4.67-6.38).

The standardized incidence ratio was “substantially” higher among never-smokers (14.50; 95% CI, 8.73-22.65) than among ever-smokers (3.50; 95% CI, 2.95-4.12), the researchers noted.

“The findings of this cohort study show that the incidence of SPLC [second primary lung cancer] is as high among never-smokers as among those with a smoking history after an IPLC [initial primary lung cancer] diagnosis, resulting in a substantially higher SIR [standardized incidence ratio] among never-smokers than ever-smokers,” the researchers summarized.

“While the reasons behind this observation are still poorly understood, the higher incidence of SPLC among never-smoking patients could be attributable to the longer survival reported in prior studies,” the researchers added. “Our findings highlight the critical need to identify risk factors for SPLC among never-smokers and to develop a targeted surveillance strategy for this patient population.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Choi E, Su CC, Wu JT, et al. Second primary lung cancer among lung cancer survivors who never smoked. JAMA Netw Open. Published online November 15, 2023. doi:10.1001/jamanetworkopen.2023.43278

This article originally appeared on Cancer Therapy Advisor