['The role of circulating TGF-beta(1) in prognosis of breast cancer (BC) was investigated with an intention to define TGF-beta(1)-dependent high risk and low risk subsets of patients.', 'Fifty three BC patients of all clinical stages and 37 healthy donors (HD) were analyzed for plasma TGF-beta(1) by the TbetaRII receptor-based Quantikine TGF-beta(1) ELISA kit.', 'The plasma TGF-beta(1) level of Stage I/II disease (median: 0.94 ng/ml; n=10)) remained close to HD (median: 1.30 ng/ml; n=37; p>0.1). In contrast, Stage III/IV disease (median: 2.34 ng/ml; n=43) exhibited highly significant TGF-beta(1) elevation (p<0.001) relative to HD. Further analysis revealed that TGF-beta(1) increase was predominantly attributed to Stage IV, metastatic disease patients (Q3=4.23 ng/ml) rather than to the group Stage III/IV (Q3=3.58 ng/ml). Using the plasma TGF-beta(1) concentration of 3.00 ng/ml as the cut-off value, two subgroups of patients were formed. Overall 2-year survival of the first subgroup, having elevated plasma TGF-beta(1) (>3.00 ng/ml; n=10), was 10%. This was significantly decreased (p<0.05) compared to 52% survival observed for the second subgroup of patients with plasma TGFbeta(1) values close to HD (<3.00 ng/ml, n=19).'] Do elevated plasma TGF-beta1 levels correlate with decreased survival of metastatic breast cancer patients?