Lung cancer as a second primary malignant tumor: prognostic values after surgical resection.

Prognostic values of lung cancers as second primary malignant tumors (LC-as-SPTs) developed after a different type of first primary malignant tumor were analyzed. Forty-three patients underwent surgery for first primary malignant tumors and later for LC-as-SPTs. The most frequent first primary tumors were: 14 laryngo-pharyngeals; 7 lungs; and 5 colons. Only metachronous cases were included in our study, and the disease-free intervals (DFI) between the first and second primary tumors were divided into two groups: shorter than 36 months (DFI<36), and longer than 36 months (DFI>36). The survival was calculated from the time of surgery for LC-as-SPT. The 5-year overall survival rate was 38%. By univariate analysis, the 5-year survival was significantly lower in cases with DFI<36 months (25%) than in cases with DFI>36 months (43%) (P=0.045), and in male (27%) than in female (62%) (P=0.032), and in N1 (31%) and N2 (0%) cases than in N0 (49%) cases (P=0.001). Using multivariate analysis with the previous factors, only the lymph node metastasis (P=0.001) had a significant impact on survival. The survival after LC-as-SPTs was shorter than after first primary lung cancer cases, and lymph node involvement had a significant impact on the postoperative survival based on uni- and multivariate analysis.