Venesection needle coring increases positive results with RT-PCR for detection of circulating cells expressing CEA mRNA

Diversity of assessing circulating tumor cells (CTCs) emphasizes need for standardization: a CTC Guide to design and report trials

Hematogenous spreading of tumor cells from primary tumors is a crucial step in the cascade to metastasis, the latter being the most limiting factor for patients' survival prognosis. Therefore, circulating tumor cells (CTCs) have become a field of intensive research. However, the process of isolation and identification of CTCs lacks standardization. This article presents an overview of 71 CTC studies reported in PUBMED since 2000 and focusing on colorectal cancer. These studies are evaluated regarding standardization of CTC isolation and identification, marker proteins used, study population and blood sample quality management, clinical performance, and quality measures. Overall, standardization of CTC assessment seems insufficient. Thus, comparability of CTC studies is hampered and results should be interpreted carefully. We here propose a standardized CTC guideline (CTC Guide) to prospectively design and report studies/trials in a harmonized form. Despite the current interstudy heterogeneity, the data indicate that CTC detection is of clinical relevance and CTCs should be considered as a surrogate prognostic marker. Many studies indicate the high potential for CTCs as prognostic markers, e.g., in colorectal cancer treatment. However, standardized, large-scale multicenter validation studies are still needed to pave the way for clinical implementation of CTC detection that could ameliorate individualized medicine regimes.

Development of a quantum-dot-labelled magnetic immunoassay method for circulating colorectal cancer cell detection

AIM: To detect of colorectal cancer (CRC) circulating tumour cells (CTCs) surface antigens, we present an assay incorporating cadmium selenide quantum dots (QDs) in these paper.

METHODS: The principle of the assay is the immunomagnetic separation of CTCs from body fluids in conjunction with QDs, using specific antibody biomarkers: epithelial cell adhesion molecule antibody, and monoclonal cytokeratin 19 antibody. The detection signal was acquired from the fluorescence signal of QDs. For the evaluation of the performance, the method under study was used to isolate the human colon adenocarcinoma cell line (DLD-1) and CTCs from CRC patients’ peripheral blood.

RESULTS: The minimum detection limit of the assay was defined to 10 DLD-1 CRC cells/mL as fluorescence was measured with a spectrofluorometer. Fluorescence-activated cell sorting analysis and Real Time RT-PCR, they both have also been used to evaluate the performance of the described method. In conclusion, we developed a simple, sensitive, efficient and of lower cost (than the existing ones) method for the detection of CRC CTCs in human samples. We have accomplished these results by using magnetic bead isolation and subsequent QD fluorescence detection.

CONCLUSION: The method described here can be easily adjusted for any other protein target of either the CTC or the host.

Role of circulating tumour cells in predicting recurrence after excision of primary colorectal carcinoma

BACKGROUND

This study assessed the potential for reverse transcriptase-polymerase chain reaction (RT-PCR)-based circulating tumour cell identification to predict colorectal cancer recurrence.

METHODS

mRNA for carcinoembryonic antigen and cytokeratin 20 was identified by RT-PCR in blood from patients with colorectal cancer, before and after primary tumour resection. Cancer recurrence was assessed at follow-up, and the accuracy of RT-PCR and primary tumour lymph node positivity in predicting recurrence was estimated.

RESULTS

One hundred and ninety-six patients with colorectal cancer were studied over a median follow-up of 1393 days from surgery. Regression analysis selected 24-h post-resection RT-PCR positivity (hazard ratio for a positive test in predicting recurrence 8.66 (95 per cent confidence interval (c.i.) 3.08 to 24.33)) before lymph node involvement (hazard ratio 7.92 (95 per cent c.i. 3.26 to 19.20)). When 24-h post-resection RT-PCR was combined with lymph node positivity, the hazard ratio increased to 18.54 (95 per cent c.i. 4.01 to 85.11), attributing a 3 per cent recurrence risk to 52 per cent, and a 50 per cent recurrence risk to 48 per cent, of patients with colorectal cancer resected with curative intent.

CONCLUSION

RT-PCR positivity within 24 h of primary colorectal cancer resection is a strong predictor of colorectal cancer recurrence, and may be useful clinically.

Detection and evaluation of epithelial cells in the blood of colon cancer patients using RT-PCR

BACKGROUND

As a mode of colorectal cancer recurrence, liver metastasis plays an important role. One of the factors reported to predict liver metastasis is the detection of trace amounts of tumor cells in the blood. For this purpose, cancer cell-induced cytokeratins (CKs) are generally identified, using the reverse transcriptase-polymerase chain reaction (RT-PCR). In the present study, we aimed to detect trace amounts of tumor cells, based on CK20, in the circulating venous blood, and we examined pathological factors, liver metastasis, and prognosis.

METHODS

The subjects were 57 colorectal cancer patients who had undergone operation. We examined the cancer-induced marker (CK20) in circulating venous blood by RT-PCR and investigated the relationships between this marker, pathological factors, and prognosis.

RESULTS

Detection ratio of CK20 mRNA was 42.1%, and CK20 was significantly correlated with the pathological factor of lymph node metastasis (P = 0.037). The 5-year survival rate for CK20-positive patients was 62.5% and that for the CK20-negative patients was 87.5%; there was a significant difference (P = 0.048) between the two groups. Recurrence was recognized in six patients; two were positive for CK20 and four were negative for CK20.

CONCLUSIONS

These findings indicate that CK20 is strongly related to lymph node metastasis and prognosis, suggesting its usefulness for the diagnosis of colorectal cancer recurrence. However, CK20 did not predict liver metastasis.

Immunobead multiplex RT-PCR detection of carcinoembryonic genes expressing cells in the blood of colorectal cancer patients

Circulating cell detection using reverse transcriptase-polymerase chain reaction (RT-PCR) techniques has been studied as a new prognostic factor in colorectal cancer patients. With the view of enhancing detection sensitivity, we developed a new multiplex RT-PCR assay for circulating cell detection based on the expression of carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5; formerly CEA) and CEACAM7 (formerly CGM2). Between November 2002 and December 2003, 45 stage III-IV, 39 stage I-II colorectal cancer patients, 32 non-colorectal cancer patients and 41 healthy individuals were included. Positive selection using HEA-125 immunobeads was applied to blood samples before mRNA extraction, cDNA synthesis and a multiplex CEACAM5/CEACAM7 RT-PCR assay. For both CEACAM5 and CEACAM7, the limit of detection was found to be as low as 1 expressing cell in 10(6) nucleated blood cells. The multiplex RT-PCR assay was negative for the 41 healthy individuals and the 32 non-colorectal cancer patients. The test was positive in 53/84 (63%) of the colorectal cancer patients for CEACAM5 and/or CEACAM7, whereas 32/84 (38%) were positive for both markers. Colorectal cancer patients were positive for one of the two markers in 80% of cases (36/45) for stage III-IV patients (CEACAM5 73%, CEACAM7 51%) and in 44% of cases (17/39) for stage I-II patients. This multiplex RT-PCR assay with two markers proved to be more sensitive than use of a single marker in detecting circulating tumour cells. The discrepant expression of CEACAM5 and CEACAM7 may label circulating tumour cells that have different levels of differentiation and subsequent aggressive behaviour.

Colorectal cancer metastasis: in the surgeon's hands?

Background

Lymphovascular ligation before tumour manipulation during colorectal cancer resection is termed the 'no-touch isolation' technique. It aims to reduce the intra-operative dissemination of colorectal cancer cells. Recently, the detection of circulating tumour cells has been enhanced by molecular biology techniques. This paper reviews the evidence for the no-touch isolation technique in light of the recent developments in circulating tumour cell detection.

Methods

Studies investigating the effect of colorectal cancer surgery on circulating tumour cells were identified by a Medline search using the subject headings colorectal neoplasms and neoplasm circulating cells together with the map term 'no-touch isolation technique'. Further references were obtained from key articles.

Results

Molecular biological techniques have improved the detection of circulating colorectal cancer cells. There is a trend towards reduced tumour cell dissemination with the no-touch technique compared with the conventional method. However the benefit in terms of improved patient survival remains unproven.

Conclusion

The no-touch isolation technique reduces circulating tumour cell dissemination but further work is needed to determine the significance of this with regards to patient survival.

Relevance of disseminated tumour cells in blood and bone marrow of patients with solid epithelial tumours in perspective

Currently-used systems to predict prognosis in patients with solid epithelial tumours after surgical resection of the tumour do not give any guarantees for the individual patient. In this respect the clinical relevance of the presence of disseminated tumour cells in blood and bone marrow has been frequently studied. Because of growing awareness that information on merely the presence of disseminated tumour cells is not sufficient for prognostic and therapeutic purposes, attention for characterization of disseminated tumour cells has increased. Numerous reviews have already been published on the detection and clinical relevance of disseminated tumour cells. Therefore, this paper will mainly focus on the biological significance of these cells and discusses the (in)efficiency of the metastatic process, the genotypic and phenotypic characteristics of disseminated tumour cells, and their structure of appearance. Despite the fact that information gained on the several individual aspects is substantial, it did not render any solid solutions for individual patient management yet. Hence, a combined approach of several aspects of disseminated tumour cells together with characteristics and behaviour of the primary tumour is needed to substantially improve our knowledge on the role of disseminated tumour cells in the complex process of tumour metastasis.

Flow cytometry correlates with RT-PCR for detection of spiked but not circulating colorectal cancer cells

The aim of this study was to determine whether flow cytometry (FACS) could detect spiked or circulating colorectal cancer cells. A flow cytometric assay was developed and its sensitivity compared with the reverse transcription polymerase-chain reaction (RT-PCR), using carcinoembryonic antigen (CEA) and cytokeratin (CK) 20 mRNA as target markers. Sensitivity limits for RT-PCR and flow cytometry (FACS) were established using spiked blood, and pre-operative blood samples from 20 colorectal cancer patients and 16 healthy no-cancer controls were analysed for circulating tumour cells (CTC) using both methods. Blood samples for FACS analysis were immuno-magnetically enriched using ferrofluid particles. CTC were defined as positive for pan-cytokeratin and negative for CD45 pan-leucocyte antigen (CK+/CD45- events). There was a significant (P < 0.0001) correlation between the number of spiked cancer cells and their recovery using FACS. The lowest detectable concentration was 20 spiked cancer cells in 14 ml blood for both RT-PCR and FACS. A positive FACS result significantly (P < 0.05) concurred with a positive RT-PCR result in spiked blood. The number of CK+/CD45- events detected in the blood of colorectal cancer patients was not significantly greater (P = 0.07) than in blood taken from 'no cancer' controls and furthermore there was no concordance (P = 1) between RT-PCR and FACS positivity in cancer patients' blood. FACS detection of tumour cells was feasible in vitro, and correlated with RT-PCR. However, its sensitivity in vivo was poor and did not correlate with RT-PCR detection of CTC. Uncertainties about antigen expression on normal circulating cells and about CTC phenotype need to be resolved, before FACS can be developed for detection of tumour cells within the circulation.

Clearance of circulating tumor cells after excision of primary colorectal cancer

OBJECTIVE

To establish whether the prevalence of positive reverse transcriptase-polymerase chain reaction (RT-PCR) results decreased during the first 3 months after colorectal cancer excision, and to assess whether persistence of RT-PCR positivity after primary colorectal cancer excision was related to tumor stage or locally advanced and metastatic disease.

METHODS

Systemic venous blood was collected from patients with colorectal cancer before and at intervals up to 12 weeks after surgery. RNA was extracted from the mononuclear cell fraction of the blood samples and subjected to RT-PCR using specific primers for carcinoembryonic antigen mRNA and cytokeratin-20 mRNA. Healthy individuals with no history of cancer were used as controls.

RESULTS

The results of RT-PCR were positive in 81 of 116 patients with colorectal cancer before surgery, with no significant differences in preoperative prevalence by Dukes stage or presence of locally advanced or metastatic disease. There was a significant decrease in the prevalence of RT-PCR positivity at 24 hours after surgery compared with before surgery. On subgroup analysis by Dukes stage, only the decrease in Dukes A and B patients reached significance. Seven of the 143 controls were RT-PCR positive.

CONCLUSIONS

Circulating tumor cells were present before treatment in most patients with colorectal cancer regardless of tumor stage or metastases. Clearance of circulating tumor cells within 24 hours of colorectal cancer excision was greatest in tumors with the best prognosis.