Lack of association between NOS3 Glu298Asp and breast cancer risk: a case-control study.

Nitric oxide (NO) plays a central role in the physiololgy and pathology of diverse tissues. Different studies provide data suggesting that the endothelial cell nitric oxide synthase (NOS3) expression in peritumoral microvessels might be a prognostic indicator in breast cancer patients. However, the putative contribution of common NOS3 germline variants to breast cancer risk remained unknown. A recent work comprising 269 breast cancer patients and 244 controls suggested that NOS3 Glu298Asp polymorphism is associated to breast cancer risk (OR=1.9). We performed an independent analysis of these results in 440 unrelated patients and 321 controls from Spanish population. Although our study was 90% powered to detect ORs >/=1.55, did not find any significant difference in the Glu298Asp allele distribution between cases and controls (P > 0.42). These putative reasons for this result are discussed.