Sensitivity of the SEPT9 Blood-Based Test in Clinical Case-Control Study of 144 Subjects. Methylated SEPT9 DNA was measured in plasma specimens donated by CRC patients and colonoscopy-confirmed control subjects. The percent of specimens with detectable methylated SEPT9 DNA is illustrated by the solid bars. The test has been maximized for sensitivity by only requiring one out of three of the PCR replicates to have methylated SEPT9 DNA detected. The specificity of the assay is 88% under these parameters. CRC, colorectal cancer; PCR polymerase chain reaction.