Clinical characteristics and prognostic analysis of multiple primary malignant neoplasms in patients with lung cancer.

Retrospective analysis of data from 14,528 lung cancer patients with multiple primary malignant neoplasm (MPMN) revealed that 2.5% (364/14,528) were MPMN cases and 96.2% (350/364) were diagnosed with two primary malignancies, 3.6% (13/364) with three primary malignancies, and 0.3% (1/364) with four primary malignancies. Among 350 lung cancer patients diagnosed with two primary malignancies, 26.6% (93/350) had lung cancer diagnosed first (LCF) and 73.4% (257/350) had other cancers diagnosed initially (OCF), whereas synchronous MPMN (SMPMN) accounted for 21.1% (74/350) and metachronous MPMN (MMPMN) accounted for 78.9% (276/350) of the cases. Detection of first primary neoplasms were at an early stage for LCF patients and the age of the first lung cancer diagnosis was 59.3 years vs. 55.4 years in the OCF group (P = 0.008), whereas the onset age of second primary neoplasm diagnosis was similar in both groups (62.5 and 61.6 years, P = 0.544). Median survival times of MMPMN and SMPMN patients in the LCF group were 6.83 and 2.42 years and in the OCF group 8.67 years and 2.25 years, respectively. Multivariate analysis showed that SMPMN, LCF and the age of the primary cancer diagnosed first ( ≥ 60 years) and NSCL staging  > II were significant independent factors for inferior prognosis of patients.