Prognostic Impact of Tumor Doubling Time in Patients with Metachronous Lung Cancer

Background: Good prognosis following surgery for metachronous lung cancer has been reported. However, prognostic factors have not been fully investigated. The purpose of this study was to identify the preoperative predictor of survival in metachronous lung cancer. Methods: Patients who underwent a second pulmonary resection for metachronous lung cancer at our institution between 2000 and 2014 were analyzed. Results: A retrospective chart review identified 86 eligible patients (of 6213; 1.4%). The 5-year overall survival was 77%. All 86 cancers met Martini and Melamed’s criteria for second primary cancer. However, on pathological examination based on morphological concordance between the initial and metachronous cancer, 73 (85%) cases were diagnosed as second primary cancer and 13 (15%) as a possible recurrent tumor. The 5-year overall survivals were 82% for second primary cancers and 52% for possible recurrent tumors. Tumor doubling time > 180 days (p < 0.001), pathological diagnosis of second primary cancer (p = 0.013), pathological stage IA (p = 0.016), interval between resections > 2 years (p = 0.040), and consolidation/tumor diameter ratio ≤ 0.5 (p = 0.045) were associated with superior overall survival. Multivariate Cox regression analysis identified tumor doubling time > 180 days as the only independent predictor of overall survival (hazard ratio 3.600, 95% confidence interval 1.226–10.338; p = 0.0196). Conclusions: Surgical resection for metachronous lung cancer is effective and feasible. Particularly, a tumor doubling time > 180 days is associated with superior survival in patients with metachronous lung cancer.