Dihydropyrimidine dehydrogenase mRNA expression in peripheral blood of rectal cancer patients is significantly associated with residual tumor and distant metastases following resection.

BACKGROUND: DPD and TS expression have been shown to correlate with response of 5-FU based chemotherapy in colorectal cancer tissue. Little is known about mRNA expression levels of TS and DPD in peripheral blood. The goals of this study were to test the feasibility of DPD and TS detection in blood and their associations to TNM staging and complete surgical resection. METHODS: Whole blood was drawn 1 day pre- and 10 days post-operatively from 23 patients with rectal cancer. Either adjuvant (n = 15) or neoadjuvant (n = 8) treatment was performed. Tumor cells were enriched from whole blood by density gradient centrifugation prior to extraction of total cellular RNA and subsequent direct quantitative reverse transcriptase-PCR assays. RESULTS: DPD was detectable in 21/23 patients (91.3%) and TS in 14/23 (61.7%). Stepwise multiple linear regression models showed a significant association of DPD expression with distant metastases (P = 0.004) and residual tumor categories (P = 0.03). CONCLUSIONS: Quantitative analysis of TS and DPD mRNA expression in peripheral blood of rectal cancer patients is technically feasible. DPD expression levels appear to be associated with residual tumor categories and might serve as a molecular marker for complete tumor resection. Larger studies seem to be warranted to scrutinize our hypothesis.

Methylated DAPK and APC promoter DNA detection in peripheral blood is significantly associated with apparent residual tumor and outcome.

BACKGROUND: Death-associated protein kinase (DAPK) and adenomatous polyposis coli gene (APC) have been recently shown to be associated with outcome in patients with esophageal carcinoma, especially adenocarcinoma. We wanted to validate the correlation of these two markers with outcome by detecting methylated DNA sequences in peripheral blood. METHODS: Circulating cell-free DNA extracted from blood plasma of 59 patients with esophageal cancer was analyzed before and after surgical resection by quantitative real-time methylation-specific RT-PCR (TaqMan) assays. RESULTS: Thirty-six of 59 patients (61.0%) with esophageal cancer had detectable levels of methylated DAPK or APC promoter DNA and preoperative detection was significantly associated with an unfavorable prognosis as revealed by multivariate Cox proportional hazards regression analysis [Exp(b) = 4.578; P = 0.01]. The combination of both markers significantly increased sensitivity and specificity for discriminating between short (<2.5 years) and long survivors (P = 0.04, ROC curve analysis). Postoperative APC detection was significantly different if residual tumor was apparent (P = 0.03). CONCLUSIONS: Preoperative measurement of methylated DAPK and APC promoter DNA in peripheral blood may contribute to better estimate postoperative survival chances of patients with esophageal carcinoma, especially adenocarcinoma. The postoperative detection of methylated APC in peripheral blood might provide crucial information on apparent residual tumor and might be used as a "molecular" R0-Marker in addition to the pathologic examination.