Prognosis of Synchronous Double Primary Lung Cancer Based on Immunohistochemical Staining

Objective: This study evaluated the prognosis of strictly selected synchronous double primary lung cancer.Methods: The records of patients who underwent complete resection for synchronous double primary lung cancer were reviewed. Only patients who had different histologic types or the same histologies without nodal metastasis or different patterns of immunohistochemical staining were included. For survival analysis, the Kaplan-Meier method was used, and for comparison of the survival rate, a log-rank test was used.Results: Eighteen males and two females with a mean age of 67.0 years were included. Eight patients (40.0%) had the same histology and 12 patients (60.0%) had different histology in each tumor. Of the eight patients with the same histology, five had squamous cell carcinoma and three had adenocarcinoma, and the immunohistochemical staining results of all eight showed different patterns of p53 and epidermal growth factor receptor expression in each tumor. The median follow-up was 33.5 months (range, 6.1–102.3 months) for all patients and 41.6 months (range, 28.9–102.3 months) for the surviving patients. The 1- and 5-year overall survival rate and disease-free survival were 80.0% and 63.3%, and 70.0% and 33.3%, respectively. The 5-year overall and diseasefree survival of patients with identical and different histology was 56.3% and 31.3%, and 66.7% and 35.0%, respectively, which was no significant difference. There were no significant prognostic factors for overall survival and disease-free survival.Conclusion: The prognosis of synchronous double primary lung cancer was good in highly selected patients with any type of surgical resection. A large number of patients is needed for appropriate and standardized selection process.