CPT® Code 81327

The CPT® Code 81327 refers to a laboratory test specifically designed to analyze the methylation status of the SEPT9 gene, which is associated with colorectal cancer (CRC). This test detects circulating methylated SEPT9 gene DNA in plasma, providing valuable information regarding the presence of colorectal cancer. The SEPT9 gene is located on the long arm of chromosome 17 at position 25 (17q25) and plays a crucial role in cellular processes such as cytoplasmic division, growth regulation, and tumor suppression. In the early stages of tumor development, particularly in colonic mucosal tissue, the V2 region of the SEPT9 promoter undergoes methylation. This hypermethylation leads to the silencing of DNA transcription, resulting in the inactivation of the gene's tumor suppression properties. Consequently, this allows for tumor cell migration and invasion, which are critical steps in the progression of colorectal cancer. During the carcinogenesis of CRC, SEPT9 DNA is released into the bloodstream from necrotic and apoptotic cancer cells, making it a significant biomarker for the disease. The sensitivity and specificity of the SEPT9 promoter methylation analysis are comparable to traditional stool sample tests for occult blood or fecal immunochemical testing. This test is particularly useful for screening adults aged 50 and older who are at average risk for colorectal cancer, especially in cases where patients have opted out of recommended colonoscopy or fecal testing. The procedure involves obtaining a blood sample through a separately reported venipuncture, followed by testing the plasma for methylated SEPT9 gene DNA using real-time polymerase chain reaction (RT-PCR) with a fluorescent hydrolysis probe. The results are reported as quantitative, indicating either a positive or negative result based on the level of SEPT9 DNA methylation detected in the blood sample. A positive result typically leads to a referral for further evaluation via colonoscopy.