SFRP2 and breast cancer: The hypermethylation in promoters of APC, SFRP1, SFRP2, SFRP5, WIF1, DKK3, ITIH5, and RASSF1A [17] are associated with the development of breast cancer, and studies have found that APC and RASSF1A are common epigenetic biomarkers for early detection of breast cancer [20–22].