Circulating transforming growth factor-β-1 and breast cancer prognosis:: results from the Shanghai Breast Cancer Study

Introduction Studies investigating the prognostic effect of circulating TGF-beta-1 in breast cancer have given inconsistent findings. The purpose of this study is to evaluate whether circulating transforming growth factor beta 1 (TGF-beta-1) is associated with overall and disease-free survival in a cohort of recently diagnosed breast cancer patients. Methods We measured TGF-beta-1 levels in plasma samples of breast cancer patients in the Shanghai Breast Cancer Study, a population-based case-control study. We evaluated the relationship between TGF-beta-1 levels and overall and disease-free survival. The median follow up time was 7.2 years. Results We observed that, compared with the patients with the lowest quartile of plasma TGF-beta-1, patients with the highest quartile of plasma TGF-beta-1 had significantly worse overall survival with hazards ratio (HR) = 2.78, with 95% confidence interval (CI): 1.34-5.79 and disease-free survival with HR = 2.49, 95% CI: 1.15-5.41, while the patients with the second and third quartiles of plasma TGF-beta-1 did not have significantly different overall and disease-free breast cancer survival. The shape of association between plasma TGF-beta-1 levels and breast cancer survival appears to be non-linear. Stratified analysis by stage of disease did not appreciably change the association pattern. Conclusions We conclude that the relationship between circulating levels of TGF-beta-1 and prognosis in breast cancer is complex and non-linear. High levels of TGF-beta-1 are associated with worse survival independent of stage of disease.