During mammary carcinogenesis, the expression of HIF‐1, a regulatory subunit of the hypoxia‐induced factor (HIF), increases proportionally to the progression from ductal hyperplastic lesion to ductal in situ carcinoma and invasive carcinoma 2, contextually to a growing expression of proangiogenic factors, including family members of vascular endothelial growth factors (VEGFs), fibroblast growth factors (FGF), transforming growth factor (TGF)‐B1, and thymidine phosphorylase (TP) 3. This evidence concerns the gene TYMP and ductal breast carcinoma in situ.