Surgical results of synchronous multiple primary lung cancers: Similar to the stage-matched solitary primary lung cancers?

Background Treatment for synchronous multiple primary lung cancers (SMPLC) remains controversial. Some surgeons treat SMPLC like advanced lung cancer, whereas other surgeons treat SMPLC as separate primary lung cancers. In this study, survival of SMPLC patients and matched-stage solitary primary lung cancer (SPLC) patients after surgical treatment were compared. Methods Prospective medical records between 2001 and 2011 were retrospectively reviewed. Results A total of 1,995 patients underwent pulmonary resection for lung cancer in a tertiary referral center. Only 97 patients met the modified criteria of Martini and Melamed for SMPLC. The median follow-up time was 38.3 months. The 3-year and 5-year overall survival rates were 83.1% and 69.6%, respectively. In the univariate analysis, males, smokers, and tumor size greater than 3 cm demonstrated significantly worse survival. After multivariate analysis, only tumor size (p = 0.018; hazard ratio 3.199) was identified as an independent predictor of survival. In addition, there was no significant difference in overall survival between the matched-stage SMPLC and SPLC without mediastinal lymph node involvement. Subgroup analysis in the multiple synchronous adenocarcinoma (n = 78) group demonstrated no significant difference between similar and different comprehensive histologic subtyping with respect to overall survival (61.3% versus 68.8%, p = 0.474). Conclusions The surgical results for SMPLC were compatible and acceptable with those for SPLC even with similar histologic subtyping, instead of T4 or M1 stages in the current TNM classification system. Preoperatively, tumor size was the only independent prognostic factor for SMPLC with surgical intervention.