p16 Methylation is frequently detected in the serum of metastatic colorectal cancer patients.

ABSTRACT

For the purpose of detection of colorectal cancers, we tried to detect p16 methylation in the serum of colorectal cancer patients using quantitative methylation-specific polymerase chain reaction (qMSP). Out of 211 serum samples derived from colorectal cancer patients, 14 (7%) exhibited p16 methylation in their serum DNA by qMSP. After completion of qMSP analysis in all specimens, clinicopathological data were correlated with the molecular analysis. Interestingly, a significant difference was observed in the presence of distant metastasis (P = 0.0420). Moreover, a trend was shown toward preferentially developing lymph node metastasis (P = 0.0547), thus suggesting that p16 methylation in serum could be detected more frequently in metastatic colorectal cancer patients. High sensitivity of qMSP makes it possible to detect smaller amounts of tumor DNA in the serum. In principle, the methylation status of a primary tumor is not required in advance to detect circulating tumor DNA, suggesting that qMSP can be used as a screening method for cancer.