[Distinguishing second primary tumors from lung metastasis in patients with postoperative non-small cell lung cancer by microsatellite analysis]

Abstract

Objective: In patients with resected early stage non-small cell lung cancer (NSCLC), intrapulmonary solitary tumor represents either second primary tumor (SPT) or a metastasis. This study is to discern SPT from lung metastasis in patients with postoperative NSCLC followed a solitary intrapulmonary tumor by microsatellite analysis.

Methods: Twenty-one patients with stage I - III(A) NSCLC resected by surgery during 1994.1 - 2002.8 were studied. Paired tumors from 21 patients with NSCLC and a solitary lung nodule were analyzed for their loss of heterozygosity (LOH) on chromosomal arms 3p, 9p and 17p. DNA from microdissected tumors and non-malignant lung tissues was subjected to polymerase chain reaction-based microsatellite analysis using 8 microsatellite markers. An effort was also made to distinguish SPT from lung metastasis on the basis of clinical and histopathologic features.

Results: The paired tumors from 7 patients had concordant patterns of LOH at all microsatellite loci suggesting the same clonal origin, and supporting metastatic spread, where 4 paired tumors had discordant patterns of at all loci suggesting independent tumor origin. These observations were supported by the clinical and pathologic findings. Additional 6 paired tumors had concordant allelic loss on 3p and discordant loss on the other, clinical characteristics supporting metastatic disease. In contrast, 2 paired tumors had concordant allelic loss on 9p or 17p but discordant loss on the 3p, clinical data supporting SPT.

Conclusions: The paired tumors from 7 patients had concordant patterns of LOH at all microsatellite loci suggesting the same clonal origin, and supporting metastatic spread, where 4 paired tumors had discordant patterns of at all loci suggesting independent tumor origin. These observations were supported by the clinical and pathologic findings. Additional 6 paired tumors had concordant allelic loss on 3p and discordant loss on the other, clinical characteristics supporting metastatic disease. In contrast, 2 paired tumors had concordant allelic loss on 9p or 17p but discordant loss on the 3p, clinical data supporting SPT.