OBJECTIVESTo detect aberrant p16 promoter methylation in serum of patients with colorectal cancer (CRC), and to explore the possibility of using this assay in early detection or as a prognostic marker.

METHODSMethylation-specific PCR was used to detect p16 methylation in DNA extracted from 52 CRCs and corresponding serum samples. Serum samples from 34 patients with adenomatous polyps and 10 healthy individuals were used as controls. The association of p16 hypermethylation in serum DNA of CRC patients with clinicopathological characteristics was analyzed.

RESULTSp16 methylation was found in 38% (20 of 52) of CRC tissues. Among the 20 patients with aberrant methylation in the tumor tissues, similar changes were also detected in the serum of 14 (70%) patients. No methylated p16 sequences were detected in the peripheral serum of the 32 CRC patients without these changes in the tumor, in 34 paitents with adenomatous polyps, or in 10 healthy controls. Clinicopathological analysis revealed that p16 methylation in serum was significantly associated with later Dukes' stage (chi(2) = 5.7, P = 0.03).

CONCLUSIONThis assay offers a potential means for the serum-based detection and/or monitoring of CRC patients.