Metastasis is responsible for determining the fate of many patients with cancer, but little is known about the molecular events by which tumor cells acquire metastatic capacity. In an Advanced Online Publication in
Comparison of 12 metastatic adenocarcinoma nodules with expression profiles of 64 primary adenocarcinomas identified 128 genes that were differentially expressed. Analysis of additional primary tumor samples revealed that the metastasis-associated genes were detectable in a subset of primary lung tumors. These patients had a poorer clinical outcome. The metastasis-linked gene set could be reduced to a 17-gene signature with good diagnostic potential. Thus, metastatic potential appears to be contained within the primary tumor gene program, rather than residing in a few rare cells within the tumor mass.