The Oncotype Dx test calculates a gene signature score through taking tissue composition into account by combining markers for both prostate cancer cells and tumor stroma, which includes SFRP4. This demonstrates that even though the evidence connecting SFRP4 mRNA levels to cancer aggressiveness is substantial, tissue composition needs to be accounted for when using SFRP4 as a clinical biomarker. The gene discussed is SFRP4; the disease is prostate cancer.