Microsatellite analysis of serum DNA in patients with oral squamous cell carcinoma

The purpose of this study was to assess the possibility of prognosis of oral squamous cell carcinoma by microsatellite blood assay. Altered microsatellite DNA in the blood of cancer patients may provide a novel method for tumor detection. DNA from normal and tumor tissues and serum obtained at two time-points (preoperatively and postoperatively) in 20 patients with oral squamous cell carcinoma was examined at 9 microsatellite loci on chromosomes 2, 3, and 21 by polymerase chain reaction (PCR)-based analysis of loss of heterozygosity (LOH). Eighteen patients (90%) showed microsatellite alterations in serum DNA identical to those in the corresponding tumor DNA. Among those showing allelic imbalance preoperatively (18 patients, 90%), 8 patients (44%) showed no evidence of allelic imbalance in serum postoperatively, and these showed no recurrence or distant metastasis. In 10 patients, allelic imbalance was detected postoperatively in serum. Seven (70%) out of these 10 patients showed an allelic imbalance at both time-points (preoperatively and postoperatively), and these patients had a poor prognosis. In conclusion, this study suggests that blood testing for circulating tumor genetic markers may provide valuable prognostic information and a guide for future therapy.