Analysis on the Prognostic and Survival Factors of Synchronous Multiple Primary Lung Cancer

Background and objective Synchronous multiple primary lung cancer (sMPLC) is a sparse disease in the past, but there has been a gradual increase in the morbidity of sMPLC recently. However, studies on large sample have never been undertaken. The purpose of this study is to investigate the diagnosis, treatment and prognosis of sMPLC through analyzing the clinical data, and provide supports for the management of sMPLC. Methods According to Martini-Melamed criteria, 357 patients were diagnosed sMPLC. The pathological staging is on the basis of the 8th edition tumor-node-metastasis (TNM) staging from International Association for the Study of Lung Cancer (IASLC). Results There were 269 patients with double primary lung cancer, 65 patients with triple primary lung cancer and 23 patients with four or more primary lung cancer. Lesions (68.55%, 571/833) were frequently in upper lobe, especially the right upper lobe. Adenocarcinoma (95.56%, 796/833) was the mainly pathological type, followed by squamous cell carcinoma (2.40%, 20/833). The acinar predominant subtype was the main part (70.81%, 313/442) of the all adenocarcinoma specimens. Most of the lesions (68.35%, 244/357) were stage Ib or low. Among the initial lesion and the following lesions ,patients who had the same pathological type (92.72%, 331/357) were more than the different (7.28%, 26/357), of which adenocarcinoma-adenocarcinoma occupied the major proportion (99.40%, 329/331). The 3-year overall survival (OS) and 5-year overall survival were respective 91.93% and 84.37%. Multivariate analysis found that smoking history (P=0.012), the diameter of the maximum lesion (P=0.027), lymph node metastasis (P=0.015) and pleural invasion (P