By contrast, expression of SFRP1, 3, and 5 only weakly or conditionally associate with Stromal Scores: for example, SFRP1 expression strongly correlates with Stromal Scores in colorectal cancer, a cancer where SFRP1 promoter methylation has been demonstrated to occur in both cell lines and patient samples13, 14. Here, SFRP1 is linked to colorectal cancer.