Impact of multiple malignancies on surgical outcomes in patients with 1 cm or smaller non-small cell lung cancer

Because most patients with small-sized non-small cell lung cancer (NSCLC) are asymptomatic, their lesions are detected by cancer screenings or routine checkups for other diseases. Incidences of multiple malignancies have been reported to be 27% in patients with stage I-III NSCLC. Some patients have treatment histories for other malignancies, and their small-sized NSCLC was incidentally detected during follow-up. There is no established report regarding the influence of multiple malignancies on small-sized NSCLC prognosis. Therefore, we investigated the correlation between multiple malignancies and surgical outcomes in patients with small-sized NSCLC. In total, 44 patients underwent definitive pulmonary resection for NSCLC of 1 cm or smaller between January 2003 and December 2012. Tumor size was measured by macroscopic findings of the resected specimens, and we then retrospectively investigated their clinical courses. One patient had hemoptysis symptoms, whereas 43 patients were asymptomatic; among them, NSCLC was detected by examinations for other diseases in 31 patients and by cancer screening in 12 patients. In total, 20 patients (45%) had multiple malignancies. The median follow-up period was 68 months. One patient had a recurrence from current NSCLC. No patients died of current NSCLC. The overall 5-year survival rate was 90% for all patients. Patients with multiple malignancies had significantly poorer prognoses compared with those without multiple malignancies (P = 0.016). However, patients with treatment intervals of more than 5 years had prognoses equivalent to those of patients without multiple malignancies (P = 0.829). Only the presence of multiple malignancies was a significantly poor prognostic factor in univariate and multivariate analyses. NSCLC of 1 cm or smaller showed good prognoses. The presence of multiple malignancies was a significantly poor prognostic factor, and short treatment intervals also correlated with poor prognosis.