Second primary lung cancers: Smokers versus nonsmokers after resection of stage I lung adenocarcinoma

Background. Smokers have a higher risk of developing non-small cell lung cancer (NSCLC) than never-smokers, but the relative risk of developing second primary lung cancer (SPLC) is unclear. Determining the risk of SPLC in smokers versus never-smokers after treatment of an initial cancer may help guide recommendations for long-term surveillance. Methods. Patients who underwent resection for stage I adenocarcinoma were identified from a prospectively maintained institutional database. Patients with other histologies, synchronous lesions, or who received neoadjuvant or adjuvant therapy were excluded. The SPLCs were identified based on Martini criteria. Results. From 1995 to 2012, a total of 2,151 patients underwent resection for stage I adenocarcinoma (308 never-smokers [14%] and 1,843 ever-smokers [86%]). SPLC developed in 30 never-smokers (9.9%) and 145 ever-smokers (7.8%). The SPLC was detected by surveillance computed tomography scan in the majority of patients (161; 92%). In total, 87% of never-smokers and 83% of ever-smokers had stage I SPLC. There was no significant difference in the cumulative incidence of SPLC between never-smokers and ever-smokers (p = 0.18) in a competing-risks analysis. The cumulative incidence at 10 years was 20.3% for never-smokers and 18.2% for ever-smokers. Conclusions. Although smokers have a greater risk of NSCLC, the risk of a second primary cancer developing after resection of stage I lung cancer is comparable between smokers and never-smokers. The majority of these second primary cancers are detectable at a curable stage. Ongoing postoperative surveillance should be recommended for all patients regardless of smoking status.