The risk of second primary tumors after resection of stage I nonsmall cell lung cancer

Background. The incidence of second primary lung cancers (SPLC) after resection of nonsmall cell lung cancer (NSCLC) is estimated to be 1% to 4% per patient year. The overall effect of SPLC on survival after resection of stage I NSCLC is unknown. Here we report the incidence, management, and outcome of SPLC in a large prospective cohort of patients who underwent careful follow-up. Methods. National Cancer Institute Intergroup Trial NCI #I91-0001 examined the effectiveness of isotretinoin A for chemoprevention of second primary tumors, the primary endpoint in that trial. Prospective data from patients randomly assigned to the placebo arm were analyzed. Results. Five hundred sixty-nine patients underwent complete resection of pathologic stage I NSCLC. The median follow-up was 5.9 years. Second primary tumors developed in 88 (15%) patients. Of these, 49 (56%) were SPLC (incidence = 1.99/100 patient-years), with a median interval from initial surgery of 4.2 years. Second primary lung cancer never developed in patients who had never smoked (n = 44, p = 0.046; never versus ever smokers). Current smokers had a higher incidence of SPLC than former smokers (hazard ratio = 1.91, p = 0.03). Age, sex, stage, histology, tumor location and initial surgery had no effect on SPLC development. Despite semiannual follow-up with chest radiographs, 12 (24%) patients had metastatic disease at the time of diagnosis of SPLC. Surgical resection was performed in 31 (63%) SPLC patients. Median survival was 4.1 years in those who underwent surgery and 1.4 years in those who did not (p = 0.003). Overall SPLC-related mortality in the original cohort was 3.7%. Conclusions. Patients who undergo surgery for SPLC can achieve prolonged survival. Despite close follow-up however many patients with SPLC present with advanced disease. That indicates a need for continued lifelong postoperative surveillance.