If healthy people average 1.04× HL, why is the threshold 1.5× and not lower?

The 1.5× HL threshold was selected based on the actual distribution of scores in healthy and cancer populations in Yenos validation studies. Healthy individuals average 1.04× HL but with individual variation (RSD 0.17) — some healthy people score as high as 1.2–1.3× HL. Cancer patients average 1.83× HL with less variation (RSD 0.09) — most score between 1.6–2.1× HL. The 1.5× threshold was selected because it falls in the gap between the upper end of the healthy distribution and the lower end of the cancer distribution — with zero overlap in published data. Setting the threshold lower (e.g., 1.2×) would include some healthy people above it, creating false positives. The 1.5× threshold maximizes sensitivity while maintaining specificity.