Loss of SFRP1 protein expression is associated with poor overall survival (OS) in patients with early breast cancer (pT1 tumours); this indicates that SFRP1 may be a putative tumor suppressor gene.  SFRP1 methylation has been shown to be an independent risk factor for OS. Veeck and colleagues demonstrate, via Kaplan-Meier analysis, that clear SFRP1 promoter methylation is associated with unfavourable prognosis.  Furthermore, a correlation between SFRP1 methylation and OS in breast cancer is dependent on a gene dose effect.  In order for the OS to be affected, a sufficient amount of tumour cells may be required to lose SFRP1 expression due to promoter methylation.