Matthias Zitt

Methylation changes in faecal DNA: a marker for colorectal cancer screening?

DNA methylation is a common molecular alteration in colorectal cancer cells. We report an assessment of faecal DNA from patients with colorectal cancer and controls to determine the feasibility, sensitivity, and specificity of this approach. By use of MethyLight analysis of faecal DNA from three independent sets of patients, we identified SFRP2 methylation as a sensitive single DNA-based marker for identification of colorectal cancer in stool samples (sensitivity 90% [CI 56-100] and specificity 77% [46-95] in the training set [n=23]; sensitivity 77% [46-95] and specificity 77% [46-95] in an independent test set [n=26]). Whether a combination of genetic and epigenetic markers will identify colorectal cancer at an early stage remains to be shown.

Circulating nucleic acids in plasma or serum (CNAPS) as prognostic and predictive markers in patients with solid neoplasias

It is now widely accepted that there is a need for the development of molecular markers of cancer that can be used for clinical prognostication and monitoring. Approximately a decade ago tumor-derived circulating nucleic acids in the plasma or serum (CNAPS) of cancer patients were introduced as a noninvasive tool for cancer detection. This review focuses on the various types of CNAPS of patients with solid neoplasias (genetic alterations in circulating DNA, microsatellites, methylated DNA, viral DNA, nucleosomes, mitochondrial DNA and cell-free mRNA) and their putative potential as prognostic or predictive parameter or even as a tool for therapy monitoring during follow-up. Additionally, this review aims to point out the difference between a prognostic and a predictive factor in patient bloodstream. However, with rapid technical improvement and well-designed studies we conclude that the next years will see CNAPS analysis integrated in the prognostication and monitoring of cancer patients, thus producing more specific treatment regimens for patients with various stages of neoplastic disease and ultimately longer survival and better quality of life.

Prostate-specific membrane antigen expression in the neovasculature of gastric and colorectal cancers

Prostate-specific membrane antigen (PSMA), a type II transmembrane metallo-peptidase highly overexpressed in prostate cancer cells, has been studied as a targeting molecule in prostate cancer. Recently, PSMA has also been found to be expressed in the neovasculature of multiple nonprostatic solid tumors. Because of its unique expression pattern limited to tumor-associated endothelial cells, PSMA may also be an interesting molecule for vascular targeting. In this study, PSMA expression was determined by immunohistochemistry in 119 cases of primary gastric adenocarcinoma, 130 cases of primary colorectal adenocarcinoma, and 24 metastasis of colorectal adenocarcinoma. Expression data were correlated with clinicopathologic information. PSMA expression was detected in tumor-associated neovasculature of 79 (66%) of 119 gastric and 110 (85%) of 130 colorectal carcinomas. Furthermore, the neovasculatures of 16 (84%) of 19 liver and 4 (80%) of 5 nodal metastases from colorectal carcinomas were prostate-specific membrane antigen positive. There was a trend for high-grade tumors to higher PSMA expression (Spearman r = 0.18, P = .046) in colorectal cancers. No association between PSMA expression and overall- or disease-free survival was observed in gastric or colorectal cancers. This study provides the first in-depth look at PSMA expression in gastric and colorectal cancer. Because of its highly tumor-restricted expression and its accessibility to targeted therapy, PSMA represents a promising therapeutic and diagnostic target in colorectal and gastric cancer.

SFRP2 methylation in fecal DNA—a marker for colorectal polyps

IntroductionDNA methylation of secreted frizzled-related proteins (SFRPs) can be detected in colorectal cancer (CRC) tissue, in tissue of adenomas, and in aberrant crypt foci, whereas in normal colorectal mucosa tissue, SFRP genes are unmethylated. Recently, our study group was able to demonstrate SFRP2 methylation as the most sensitive single DNA-based marker in stool for identification of CRC. The purpose of this study was to clarify whether SFRP2 methylation in fecal DNA can be found in stool of individuals with hyperplastic and adenomatous colorectal polyps.Materials and methodsPatients who were diagnosed with colorectal polyps or showed negative colonoscopy were included in this study. DNA from stool samples was isolated. SFRP2 methylation was assessed by means of MethyLight.ResultsStool samples from 68 individuals were checked for DNA content; 23% of the samples (6 of 26) from healthy controls, 46% of the samples (6 of 13) from patients with hyperplastic polyps, and 45% of the samples (13 of 29) from patients with adenomas were positive for human DNA. SFRP2 methylation in stool samples was found in none of the healthy controls, in 33% (2 of 6) patients with hyperplastic polyps, and in 46% (6 of 13) patients with adenomas. Statistical analysis revealed that the frequency of SFRP2 methylation increased significantly (P = 0.028) from healthy controls to patients with hyperplastic polyps and to patients with adenomas.ConclusionsIn the current study, we report for the first time that SFRP2 methylation in fecal DNA increases significantly from healthy controls to patients with hyperplastic polyps and to patients with adenomas. SFRP2 methylation may serve as a marker for molecular stool-based adenoma and CRC screening.

DNA methylation in colorectal cancer – Impact on screening and therapy monitoring modalities?

Colorectal cancer (CRC) is a common malignancy. It arises from benign neoplasms and evolves into adenocarcinomas through a stepwise histological progression sequence, proceeding from either adenomas or hyperplastic polyps/serrated adenomas. Genetic alterations have been associated with specific steps in this adenoma-carcinoma sequence and are believed to drive the histological progression of CRC. Recently, epigenetic alterations (especially DNA methylation) have been shown to occur in colon polyps and CRC. The aberrant methylation of genes appears to act together with genetic alterations to drive the initiation and progression of colon polyps to CRC. DNA methylation changes have been recognized as one of the most common molecular alterations in human tumors, including CRC. Because of the ubiquity of DNA methylation changes and the ability to detect methylated DNA in several body fluids (blood, stool), this specifically altered DNA may serve, on the one hand, as a possible new screening marker for CRC and, on the other hand, as a tool for therapy monitoring in patients having had neoplastic disease of the colorectum. As many CRC patients present with advanced disease, early detection seems to be one of the most important approaches to reduce mortality. Therefore, an effective screening test would have substantial clinical benefits. Furthermore, early detection of progression of disease in patients having had CRC permits immediate commencement of specific treatment regimens (e.g. curative resection of liver and lung metastases) and probably longer survival and better quality of life.

Circulating cell-free DNA in plasma of locally advanced rectal cancer patients undergoing preoperative chemoradiation: A potential diagnostic tool for therapy monitoring

Circulating cell-free DNA opens up an interesting field for therapy monitoring, in particular during multimodal therapy protocols. The objective of this proof of principle study was to evaluate whether the amount of circulating plasma DNA has the potential to serve as a marker for therapy monitoring during the treatment course of locally advanced rectal cancer patients. We especially focused on kinetics of circulating DNA to assess whether variances in kinetics have the potential to discriminate between therapy responders and nonresponders. The amount of circulating DNA in plasma of rectal cancer patients undergoing preoperative chemoradiation was determined using real-time PCR before chemoradiation, after the end of chemoradiation and at the end of treatment. The study population was divided into responders (ypT0-T2 stage) and nonresponders (ypT3-T4 stage). Both groups showed comparable median plasma DNA values before and after the end of chemoradiation. At the end of treatment responders showed a further decrease in circulating DNA, whereas in nonresponders the circulating DNA manifestly increased (P = 0.006). This study demonstrates that circulating DNA in plasma of rectal cancer patients undergoing preoperative chemoradiation might serve as a surrogate marker to discriminate between responders and nonresponders. Therefore, we hypothesize that quantification of plasma DNA could be of use as an easily accessible tool for therapy monitoring in these patients.

Quantification of circulating endothelial and progenitor cells: comparison of quantitative PCR and four-channel flow cytometry

BackgroundCirculating endothelial cells (CEC) and endothelial precursor cells (CEP) have been suggested as markers for angiogenesis in cancer. However, CEC/CEP represent a tiny and heterogeneous cell population, rendering a standardized monitoring in peripheral blood difficult. Thus, we investigated whether a PCR-based detection method of CEC/CEP might overcome the limitations of rare-event flow cytometry.FindingsTo test the sensitivity of both assays endothelial colony forming cell clones (ECFC) and cord blood derived CD45- CD34+ progenitor cells were spiked into peripheral blood mononuclear cells (PBMNC) of healthy volunteers. Samples were analyzed for the expression of CD45, CD31, CD34, KDR or CD133 by 4-color flow cytometry and for the expression of CD34, CD133, KDR and CD144 by qPCR. Applying flow cytometry, spiked ECFC and progenitor cells were detectable at frequencies ≥ 0.01%, whereas by qPCR a detection limit of 0.001% was achievable. Furthermore, PBMNC from healthy controls (n = 30), patients with locally advanced rectal cancer (n = 20) and metastatic non-small cell lung cancer (NSCLC, n = 25) were analyzed. No increase of CEC/CEP was detectable by flow cytometry. Furthermore, only CD34 and KDR gene expression was significantly elevated in patients with metastatic NSCLC. However, both markers are not specific for endothelial cells.ConclusionQPCR is more sensitive, but less specific than 4-channel flow cytometry for the detection of CEC/CEP cell types. However, both methods failed to reliably detect an increase of CEC/CEP in tumor patients. Thus, more specific CEC/CEP markers are needed to validate and improve the detection of these rare cell types by PCR-based assays.

Preoperative Oxaliplatin, Capecitabine, and External Beam Radiotherapy in Patients with Newly Diagnosed, Primary Operable, cT3NxM0, Low Rectal Cancer

AbstractPurpose:In patients with locally advanced rectal cancer (LARC), preoperative chemoradiation is known to improve local control, and down-staging of the tumor serves as a surrogate for survival. Intensification of the systemic therapy may lead to higher downstaging rates and, thus, enhance survival. This phase II study investigated the efficacy and safety of preoperative capecitabine and oxaliplatin in combination with radiotherapy.Patients and Methods:Patients with LARC of the mid and lower rectum, T3NxM0 staged by MRI received radiotherapy (total dose 45 Gy) in combination with oral capecitabine (825 mg/m2 twice a day on radiotherapy days; weeks 1–4) and oxaliplatin 50 mg/m2 intravenously (days 1, 8, 15, and 22). Efficacy was evaluated as rate of tumor down-categorization at the T level.Results:A total of 59 patients were enrolled (19 women, 40 men; median age of 61 years) and all were evaluable for efficacy and toxicity. Down-categorization at the T level was observed in 53% with pathological complete response in 6 patients (10%). Actual total radiotherapy, oxaliplatin and capecitabine doses received were 97%, 90%, and 93% of the protocol-specified preplanned doses, respectively. Grade 3/4 toxicity was observed in 15 patients (25%). The most frequent was diarrhea (12%).Conclusions:Preoperative chemoradiation with capecitabine and oxaliplatin is feasible in patients with MRI-proven cT3 LARC. The only clinically relevant toxicity was diarrhea. Overall, efficacy of the multimodality treatment was good, but not markedly exceeding that of 5-FU- or capecitabine-based chemoradiation approaches.ZusammenfassungZiel:Eine präoperative Radiochemotherapie verbessert bei Patienten mit einem tief sitzenden Rektumkarzinom (LARC) die lokale Tumorkontrolle und ein so genanntes „down-staging“ dient als Überlebenssurrogatparameter. Von einer Dosisintensivierung der systemischen Therapie kann man sich höhere Down-Staging-Raten erwarten und damit das Überleben verbessern. Diese multizentrische Phase-II-Studie soll die Wirksamkeit und Toxizität einer neoadjuvanten durch Capecitabin und Oxaliplatin intensivierten Radiochemotherapie prüfen.Patienten und Methodik:Patienten mit einem LARC, das mittels MRI als cT3NxM0 klassifizierten wurde, erhielten eine Radiotherapie (45 Gy in konventioneller Fraktionierung) mit konkomitanter Gabe von Capecitabin (oral 2 x täglich 825 mg an den Bestrahlungstagen, Woche 1–4) und Oxaliplatin intravenös 50mg/m2 (an den Tagen 1, 8, 15 und 22). Die Rate an Tumor-Down- Categorization dient als Parameter der Wirksamkeit.Ergebnisse:59 Patienten (davon 68% männlich, mittleres Alter 61 Jahre) wurden in die Studie eingeschlossen. Eine Down- Categorization in der T-Kategorie wurde in 53% der Patienten beobachtet, wobei 6 Patienten (10%) eine komplette pathologische Remission zeigten. Die tatsächlich verabreichte Strahlendosis betrug 97%, die Capecitabindosis 93% und die Oxaliplatindosis 90% der im Protokoll festgelegten Gesamtdosis. Akute Nebenwirkungen CTC-Grad ≥3 (Common Toxicity Criteria) wurden in 15 Patienten (25%) registriert, wobei mit 12% eine Diarrhoe am häufigsten vorkam.Schlussfolgerung:Eine präoperative Radiochemotherapie mit Capecitabin und Oxaliplatin ist bei Patienten mit mittels MRI diagnostiziertem cT3 LARC gut durchführbar. Die einzige klinisch relevante Nebenwirkung war eine Diarrhoe. Allerdings übertrifft die Wirksamkeit nicht wesentlich die bisherigen Erkenntnisse von Studien mit kontinuierlicher 5-Fluorouracil- oder alleiniger Capecitabingabe.

Dickkopf-3 As a New Potential Marker for Neoangiogenesis in Colorectal Cancer: Expression in Cancer Tissue and Adjacent Non-Cancerous Tissue

Gene expression of Dickkopf-3 (Dkk-3) has been shown to be upregulated in tumor endothelium of colorectal cancer (CRC). For the first time, we analyzed Dkk-3 protein expression in CRC and its potential as a marker for neoangiogenesis. We used tissue microarrays (TMAs) to investigate Dkk-3 in microvessels of 403 CRC samples, 318 appropriate adjacent non-cancerous samples and 127 normal colorectal samples. Of cancer samples with CD31-positive microvessels, 67.7% were positive for Dkk-3. Dkk-3 staining was demonstrated in endothelial cells of all microvessels in nearly all cases. Dkk-3-positive samples showed a higher mean microvessel count than did Dkk-3-negative samples (P=0.001). Dkk-3 expression increased with rising numbers of microvessels per sample (P<0.0001). In adjacent samples with CD31-positive microvessels, 56% were Dkk-3-positive in all microvessels. Similar to cancer samples, Dkk-3-positive adjacent samples had a higher mean microvessel count than did Dkk-3-negative samples (P<0.0001), and Dkk-3 expression also increased with rising numbers of microvessels (P<0.0001). All microvessels in normal mucosa samples were negative for Dkk-3. Dkk-3 can be considered a putative pro-angiogenic protein in neovascularization and may possibly be a marker for neoangiogenesis in CRC. Further investigations will elucidate whether Dkk-3 is a target structure for novel therapies.

Ventral Hernia Repair in Bariatric Surgery

Background: Obesity is an important risk factor for perioperative complications including the development of ventral hernias. Methods: This retrospective study comprises patients who underwent abdominal hernia repair simultaneously with or following implantation of a Swedish Adjustable Gastric Band® (SAGB). Results: 9 out of 415 patients (2.2%) who received a SAGB between January 1996 and June 2001 underwent ventral hernia repair. In 6 patients, hernias preexisted from previous abdominal surgery at the time of the bariatric procedure, and another 3 hernias occurred at the median and left upper abdominal trocar position following SAGB placement. Median BMI at time of SAGB implantation was 44 (range 35-52), and at time of hernia repair was 36 (range 25-46). 2 hernias were repaired during SAGB placement, 3 during redo surgery, and 2 during abdominoplasty. In 2 patients, significant weight loss with loss of soft tissue support of the hernia sac led to recurrent episodes of small bowel obstruction necessitating emergency repair. Repair included direct defect closure in 7 patients and sublay polypropylene net implantation in 2 patients. Recoveries have been uneventful without wound infections or recurrence in all patients after a median follow-up of 34 months (range 13-69). Conclusion: In morbidly obese patients, the optimal management and timing of incisional hernia repair should weigh the risk of recurrence and perioperative complications against the risk of hernia-associated complications.