Since this epigenetic alteration of the Igf1 Pr1 was observed in mammary stromal cells from prepubertal animals, and DNA methylation is a stable epigenetic marker that can be inherited through multiple cell divisions [13,45], our results also indicate that methylation of the Igf1 Pr1 promoter in mammary tissues could be used as an epigenetic biomarker for early breast cancer risk assessment. This evidence concerns the gene TMEM37 and breast carcinoma.