Prognostic significance of circulating tumor cells in patients with metastatic colorectal cancer

Circulating tumor cells as biomarkers in prostate cancer

Unmet needs in prostate cancer drug development and patient management are the ability to monitor treatment effects and to identify therapeutic targets in a tumor at the time treatment is being considered. This review focuses on establishing analytically valid biomarkers for specific contexts of use in patients with castration-resistant prostate cancer (CRPC), emphasizing a biomarker currently in clinical use, circulating tumor cells (CTC). The FDA Critical Path provides a road map for these investigations, which, if followed, will facilitate the incorporation of these types of assays into clinical decision-making. CTC enumeration at baseline and post-treatment is prognostic of survival, with no threshold effect, and the shedding of cells into the circulation represents an intrinsic property of the tumor, distinct from extent of disease. The clinical utility of monitoring CTC changes with treatment, as an efficacy-response surrogate biomarker of survival, is currently being tested in large phase III trials, with the novel antiandrogen therapies abiraterone acetate and MDV3100. Molecular determinants can be identified and characterized in CTCs as potential predictive biomarkers of tumor sensitivity to a therapeutic modality. Additionally, we discuss novel technologies to enrich and characterize CTCs from more patients, the potential clinical uses of CTCs in determining prognosis and monitoring treatment effects, and CTCs as a source of tissue to identify predictive markers of drug sensitivity to guide treatment selection. Prospective studies, designed around the biomarker itself and the specific clinical context for which it is applied, are needed to further assess the role of these and novel markers in clinical practice.

Phase II trial of the mTOR inhibitor, temsirolimus and evaluation of circulating tumor cells and tumor biomarkers in persistent and recurrent epithelial ovarian and primary peritoneal malignancies: a Gynecologic Oncology Group study

OBJECTIVE

Patients with persistent/recurrent epithelial ovarian cancer/primary peritoneal cancer (EOC/PPC) have limited treatment options. AKT and PI3K pathway activation is common in EOC/PPC, resulting in constitutive activation of downstream mTOR. The GOG conducted a phase II evaluation of efficacy and safety for the mTOR inhibitor, temsirolimus in EOC/PPC and explored circulating tumor cells (CTC) and AKT/mTOR/downstream tumor markers.

METHODS

Eligible women with measurable, persistent/recurrent EOC/PPC who had received 1-3 prior regimens were treated with 25mg weekly IV temsirolimus until progression or intolerable toxicity. Primary endpoints were progression-free survival (PFS) ≥6-months, tumor response, and toxicity. CellSearch® system was used to examine CTC, and AKT/mTOR/downstream markers were evaluated by archival tumor immunohistochemistry. Kendall's tau-b correlation coefficient (r) and Cox regression modeling were used to explore marker associations with baseline characteristics and outcome.

RESULTS

Sixty patients were enrolled in a two-stage sequential design. Of 54 eligible and evaluable patients, 24.1% (90% CI 14.9%-38.6%) had PFS ≥6 months (median 3.1 months), 9.3% (90% CI 3.7%-23.4%) experienced a partial response. Grade 3/4 adverse events included metabolic (8), gastrointestinal (8), pain (6), constitutional (5) and pulmonary (4). Suggested associations were between cyclin D1 and PFS ≥6 months, PFS or survival; positive CTC pre-treatment and lack of response; and high CTC expression of M30 and PFS ≥6 months/longer PFS.

CONCLUSIONS

Temsirolimus appears to have modest activity in persistent/recurrent EOC/PPC; however, PFS is just below that required to warrant inclusion in phase III studies in unselected patients. Cyclin D1 as a selection marker and CTC measures merit further study.

Biomarker-based selection of therapy for colorectal cancer

Colorectal cancer (CRC) has been re-classified based on molecular analyses of various genes and proteins capable of separating morphologic types of tumors into molecular categories. The diagnosis and management of CRC has evolved with the discovery and validation of a wide variety of biomarkers designed to facilitate a personalized approach for the treatment of the disease. In addition, a number of new prognostic and predictive individual genes and proteins have been discovered that are designed to reflect the sensitivity and/or resistance of CRC to existing therapies. Multigene predictors have also been developed to predict the risk of relapse for intermediate-stage CRC after completion of surgical resection. Finally, a number of biomarkers have been proposed as specific predictors of chemotherapy and radiotherapy response and, in some instances, drug toxicity. In this article, a series of novel biomarkers are considered and compared with standard-of-care markers for their potential use as pharmacogenomic and pharmacogenetic predictors of disease outcome.

A glimpse of the future: where will new combinations of diagnostics and therapies take us?

The field of radiation oncology has evolved, especially in the past 20 years. Advances in technology, particularly in computing power, software, and imaging, have fueled contributions to cancer care. It is currently fashionable to say that many of these advances have only served to increase costs of care without clear evidence of benefit, and certainly, efforts to evaluate the value of radiation oncology treatments are needed. However, it is undeniable that the future of radiation oncology depends on discovering such advances and to demonstrate that these increase the therapeutic index of treatment. Across the global radiation oncology community, investigations are proceeding in which innovative means are being used to achieve this goal. We review some of these novel methods to improve the therapeutic index of radiation therapy.

End points and outcomes in castration-resistant prostate cancer: from clinical trials to clinical practice

New therapeutic approaches for castration-resistant prostate cancer (CRPC) introduce new treatment dilemmas: how best to sequence these options to maximally benefit patients, what tests to perform before and after treatment to assess disease status, and how to interpret the test results and use them to guide treatment. New and specific end points for different classes of drugs are needed to provide the information to guide these treatment decisions. In 2008, the Prostate Cancer Working Group 2 consensus criteria for early-phase clinical trials redefined clinical trial end points as first, to control, relieve, or eliminate disease manifestations present when treatment is started and second, to prevent or delay future disease manifestations. Disease manifestations include prostate-specific antigen (PSA), soft-tissue disease (nodes and/or viscera), bone disease (most common site of spread), and symptoms. Recent US Food and Drug Administration (FDA) approvals for CRPC therapies have been based on the prevent/delay end points that reflect unequivocal benefit to a patient: prolongation of life or reduction in skeletal-related events (SREs). For the practicing oncologist, the control/relieve/eliminate outcomes should serve primarily to inform the decision of whether to continue therapy. In this review, we consider individual end points such as PSA, imaging, and patient-reported outcomes in the context of the control/relieve/eliminate and prevent/delay framework. We address the time-to-event end points of metastasis prevention, SRE, time to progression, and overall survival in the context of regulatory approvals. We also discuss circulating tumor cells measured with the CellSearch assay, recently cleared by the FDA for monitoring CRPC.

CGB and GNRH1 expression analysis as a method of tumor cells metastatic spread detection in patients with gynecological malignances

BACKGROUND

Metastasis is a common feature of many advanced stage cancers and metastatic spread is thought to be responsible for cancer progression. Most cancer cells are localized in the primary tumor and only a small population of circulating tumor cells (CTC) has metastatic potential. CTC amount reflects the aggressiveness of tumors, therefore their detection can be used to determine the prognosis and treatment of cancer patients.The aim of this study was to evaluate human chorionic gonadotropin beta subunit (CGB) and gonadoliberin type 1 (GNRH1) expression as markers of tumor cells circulating in peripheral blood of gynecological cancer patients, indicating the metastatic spread of tumor.

METHODS

CGB and GNRH1 expression level in tumor tissue and blood of cancer patients was assessed by real-time RT-PCR. The data was analyzed using the Mann-Whitney U and Spearman tests. In order to distinguish populations with homogeneous genes' expression the maximal likelihood method for one- and multiplied normal distribution was used.

RESULT

Real time RT-PCR results revealed CGB and GNRH1 genes activity in both tumor tissue and blood of gynecological cancers patients. While the expression of both genes characterized all examined tumor tissues, in case of blood analysis, the transcripts of GNRH1 were found in all cancer patients while CGB were present in 93% of patients. CGB and GNRH1 activity was detected also in control group, which consisted of tissue lacking cancerous changes and blood of healthy volunteers. The log-transformation of raw data fitted to multiplied normal distribution model showed that CGB and GNRH1 expression is heterogeneous and more than one population can be distinguished within defined groups.Based on CGB gene activity a critical value indicating the presence of cancer cells in studied blood was distinguished. In case of GNRH1 this value was not established since the results of the gene expression in blood of cancer patients and healthy volunteers were overlapping. However one subpopulation consists of cancer patient with much higher GNRH1 expression than in control group was found.

CONCLUSIONS

Assessment of CGB and GNRH1 expression level in cancer patients' blood may be useful for indicating metastatic spread of tumor cells.

Circulating tumor cells: advances in detection methods, biological issues, and clinical relevance

BACKGROUND

Circulating tumor cells (CTCs) have long been considered a reflection of tumor aggressiveness. Hematogenous spreading of CTCs from a primary tumor is a crucial step in the metastasis cascade, which leads ultimately to the formation of overt metastases. However, owing to the rarity of CTCs in peripheral blood, detecting these cells requires methods combined with high sensitivity and specificity, which sets tremendous challenges for the implementation of these assays into clinical routine.

METHODS

Generally, CTCs detection methods are composed of the following two steps: enrichment (isolation) process (morphological and immunological techniques) and detection (identification) process (cytometric and nucleic acid techniques), which may or may not be separate from enrichment. Genetic and molecular characterization of CTCs carried out by fluorescent in situ hybridization (FISH), comparative genomic hybridization (CGH), PCR-based techniques, and biomarker immunofluorescent staining extract more information about malignant profile, metastatic potential of CTCs, and the extent to which CTCs are genetically identical to the primary tumor.

RESULTS

Recent technical advances made it possible to detect CTCs. The efficacy of circulating tumor cell (CTC) detection among patients with solid malignancy has been investigated, which shows great potential to become a tool for real-time parameter of prognosis and serve as an early marker to assess the therapeutic response in overt cancers. Improvements in detection and characterization of CTCs will hopefully lead to refinement of clinical management of cancer patients.

CONCLUSION

This review addresses the majority of assays that have been published thus far, including the enrichment and detection steps and the markers used in these assays, accompanied by some biological issues of CTC and the results of clinical application harvested.

Chemotaxis in cancer

Chemotaxis of tumour cells and stromal cells in the surrounding microenvironment is an essential component of tumour dissemination during progression and metastasis. This Review summarizes how chemotaxis directs the different behaviours of tumour cells and stromal cells in vivo, how molecular pathways regulate chemotaxis in tumour cells and how chemotaxis choreographs cell behaviour to shape the tumour microenvironment and to determine metastatic spread. The central importance of chemotaxis in cancer progression is highlighted by discussion of the use of chemotaxis as a prognostic marker, a treatment end point and a target of therapeutic intervention.

Usefulness of transcription-reverse transcription concerted reaction method for detecting circulating tumor cells in patients with colorectal cancer

PURPOSE

The CellSearch system (Veridex, LLC) is useful for detecting circulating tumor cells (CTCs) in various carcinomas, including colorectal cancer (CRC); however, there are some problems associated with its clinical use. A transcription-reverse transcription concerted reaction (TRC) method, which is a PCR-based technique producing more stable and reliable results, because it is a more simplified process compared with the conventional techniques, has been introduced for detecting micrometastasis in some carcinomas. We aimed to demonstrate the effectiveness of TRC method in the CTC detection.

METHODS

We compared the two methods for the sensitivity for CTC detection using the colon cancer cell line and 42 whole-blood samples from patients with advanced or metastatic CRC. Furthermore, 25 patients with metastatic CRC were enrolled to investigate the correlation between CTC detection and prognosis in both methods.

RESULTS

The sensitivity of the TRC method was similar to that of the CellSearch system. The overall survival rate was significantly worse in the patients diagnosed as CTC-positive by the TRC method than in those diagnosed as CTC-negative; this finding was similar to the prognosis indicated by the CellSearch system. However, clinically, the TRC method could detect CTCs more rapidly and at a reduced cost compared with the CellSearch system.

CONCLUSIONS

The TRC method seems to be a useful alternative to the CellSearch system for clinically detecting CTCs in patients with metastatic CRC.

Decreased incidence of isolated tumor cells in lymph nodes after laparoscopic resection for colorectal cancer

Background

Laparoscopic surgery has potential for less tumor cell spread because of the no-touch technique. We assessed the effect of the surgical approach (open versus no-touch laparoscopic) on the presence of tumor cells in sentinel lymph nodes (SN) of patients with stage I and II colorectal cancer.

Methods

A single-center consecutive prospective series of patients operated on for colorectal cancer was analyzed. After conventional hematoxylin and eosin (H&E) staining, 107 patients without lymphatic metastases were included; 59 patients had open surgery, and 48 patients underwent laparoscopic resection. Patients in the laparoscopic group underwent a no-touch medial to lateral approach, whereas the conventional lateral to medial approach was applied in open surgery. A SN procedure was performed in all patients. The SNs were immunohistochemically analyzed for presence of occult tumor cells (OTC). According to the American Joint Committee on Cancer (AJCC) these tumor cells were divided into micrometastases (0.2–2 mm) or isolated tumor cells (ITC, < 0.2 mm).

Results

In ten patients micrometastases were found, equally distributed between the two groups. However, ITC were more often found after open surgery (18 versus 5 patients, p = 0.03). Presence of OTC was related to depth of tumor invasion and tumor diameter > 3.5 cm. Logistic regression analysis identified lymphovascular invasion as a predictor for micrometastases [odds ratio (OR) 18.4], whereas open resection was predictive for presence of ITC (OR 3.3).

Conclusions

No-touch medial to lateral laparoscopic surgery results in less isolated tumor cells in lymph nodes compared with open lateral to medial surgery in patients with stage I and II colorectal cancer.

Disseminated and circulating tumor cells in gastrointestinal oncology

Circulating (CTCs) and disseminated tumor cells (DTCs) are two different steps in the metastatic process. Several recent techniques have allowed detection of these cells in patients, and have generated many results using different isolation techniques in small cohorts. Herein, we review the detection results and their clinical consequence in esophageal, gastric, pancreatic, colorectal, and liver carcinomas, and discuss their possible applications as new biomarkers.

Circulating tumor cells in prostate cancer: a potential surrogate marker of survival

Prostate-specific antigen (PSA) levels in blood are widely used in prostate cancer (PCa) for the management of this disease at every stage of progression. Currently, PSA levels combined with clinical stage and Gleason score provide the best predictor of survival and the main element to monitor treatment efficiency. However, these areas could be improved by utilizing emerging biomarkers. Recently, circulating tumor cells (CTCs) and disseminating tumor cells (DTCs) have been detected in PCa and may be a new surrogate candidate. Here we provide a systematic review of the literature in order to describe the current evidence of CTC/DTC surrogacy regarding outcome of prostate cancer patients. We also discuss several markers that could be used to increase the sensitivity and specificity of CTC/DTC detection. CTC/DTC detection is performed using a wide variety of techniques. Initially, reverse transcriptase polymerase chain reaction (RT-PCR) based methods were utilized with weak correlation between their positive detection and patients' outcome. More recent immunological techniques have indicated a reproducible correlation with outcome. Such surrogate markers may enable clinicians to provide early detection for inefficient treatments and patients with poor prognosis that are candidates for treatment intensification. Dissecting the micrometastasis phenomenon in CTCs/DTCs is a key point to increase surrogacy of this biomarker.

Circulating tumor cells predict progression free survival and overall survival in patients with relapsed/recurrent advanced ovarian cancer

OBJECTIVE

Serial circulating tumor cell (CTC) counts have demonstrated predictive and prognostic value in patients with metastatic breast, colorectal, and prostate cancer. In a phase III study of pegylated liposomal doxorubicin (PLD) with trabectedin vs. PLD for relapsed ovarian cancer, we evaluated the correlation, if any, between numbers of CTCs and progression free survival, (PFS) and overall survival (OS).

METHODS

CTCs were isolated from peripheral blood (10 mL) using the CellSearch system and reagents (Veridex). A CTC is defined as EpCAM+, cytokeratin+, CD45-, and is positive for the nuclear stain DAPI. The normal reference range for CellSearch is <2 CTC/7.5 mL of blood. Hazard ratios adjusted for known prognostic factors were estimated by Cox regression.

RESULTS

Two-hundred sixteen patients had baseline CTC measurements of which 111 (51.4%) were randomized to the trabectedin+PLD arm; 143/216 patients (66.2%) were platinum-sensitive. Thirty-one of 216 patients (14.4%) had 2 or more CTCs detected prior to the start of therapy (range 2-566). Univariate Cox regression analyses indicated that patients with ≥2 CTCs prior to therapy had 1.89- (p=0.003) and 2.06-fold (p=0.003) higher risk for progression and death respectively. Multivariate analyses that include baseline CA-125, platinum sensitivity status, largest diameter lesion, number of tumor lesions, ECOG PS, and tumor grade show that patients with elevated baseline CTC had 1.58- (p=0.058) and 1.54-fold (p=0.096) higher risk for progression and death respectively.

CONCLUSIONS

Results from this study indicate that elevated numbers of CTCs impart an unfavorable prognosis for ovarian cancer patients.

Personalized colon cancer care in 2010

Colon cancer (CC) therapies have improved patient outcomes significantly over the last decades in both the adjuvant and metastatic settings. With the introduction of a number of novel agents, both traditional chemotherapies and biologically targeted agents, the need to identify subgroups that are likely and not likely to respond to a particular treatment regimen is paramount. This will allow patients who are likely to benefit to receive optimal care, while sparing those unlikely to benefit from unnecessary toxicity and cost. With the identification of several novel biomarkers and a variety of technologies to interrogate the genome, we already are able to rapidly study patient tumor or blood samples and normal tissues to generate a large dataset of aberrations within the cancer. How to digest this complex information to obtain accurate, reliable, and meaningful results that will allow us to provide truly personalized care for CC patients is just starting to be addressed. In this article, we briefly review the history of CC treatment, with an emphasis on current clinical standards that incorporate a "personalized medicine" approach. We then review strategies that will potentially improve our ability to individualize therapy in the future.

Detection of the circulating tumor cells in cancer patients

As the presence of tumor cells circulating in the blood is associated with systemic disease and shortened survival, the establishment of a method to detect circulating tumor cells (CTCs) is of critical importance for a more concise staging and follow-up of cancer patients. Recently, the most robust strategies for the determination of CTCs are the PCR-based methods and the CellSearch® system that exploits the immunofluorescent characterization and isolation of cancer cells. Herein, we analyzed the experimental strategies used for determining CTCs with respect to accuracy, sensitivity and reproducibility in cancers of the breast, colon, prostate and melanoma.

Predictive and prognostic factors in colorectal cancer: a personalized approach

It is an exciting time for all those engaged in the treatment of colorectal cancer. The advent of new therapies presents the opportunity for a personalized approach to the patient. This approach considers the complex genetic mechanisms involved in tumorigenesis in addition to classical clinicopathological staging. The potential predictive and prognostic biomarkers which have stemmed from the study of the genetic basis of colorectal cancer and therapeutics are discussed with a focus on mismatch repair status, KRAS, BRAF, 18qLOH, CIMP and TGF-β.

Detection of circulating tumor cells: Clinical relevance of a novel metastatic tumor marker

Most cancer-related deaths are caused by the hematogenous spread of cancer cells to distant organs and their subsequent metastasis. During the early stages of the metastatic cascade, cancer cells disseminate from the primary site via the lymphatic vessels and/or by hematogenous routes. Circulating tumor cells (CTCs), cancer cells that have disseminated into the systemic circulation, may be a predictor of poor prognosis in several carcinomas. An understanding of the molecular mechanisms involved in the blood-borne dissemination of cancer cells may help to clarify the process of metastasis and provide a powerful and non-invasive approach for anticancer treatments that are tailored to individual patients.

Evaluation and prognostic significance of circulating tumor cells in patients with non-small-cell lung cancer

PURPOSE

Lung cancer is the leading cause of cancer-related death worldwide. Non-small-cell lung cancer (NSCLC) lacks validated biomarkers to predict treatment response. This study investigated whether circulating tumor cells (CTCs) are detectable in patients with NSCLC and what their ability might be to provide prognostic information and/or early indication of patient response to conventional therapy.

PATIENTS AND METHODS

In this single-center prospective study, blood samples for CTC analysis were obtained from 101 patients with previously untreated, stage III or IV NSCLC both before and after administration of one cycle of standard chemotherapy. CTCs were measured using a semiautomated, epithelial cell adhesion molecule-based immunomagnetic technique.

RESULTS

The number of CTCs in 7.5 mL of blood was higher in patients with stage IV NSCLC (n = 60; range, 0 to 146) compared with patients with stage IIIB (n = 27; range, 0 to 3) or IIIA disease (n = 14; no CTCs detected). In univariate analysis, progression-free survival was 6.8 v 2.4 months with P < .001, and overall survival (OS) was 8.1 v 4.3 months with P < .001 for patients with fewer than five CTCs compared with five or more CTCs before chemotherapy, respectively. In multivariate analysis, CTC number was the strongest predictor of OS (hazard ratio [HR], 7.92; 95% CI, 2.85 to 22.01; P < .001), and the point estimate of the HR was increased with incorporation of a second CTC sample that was taken after one cycle of chemotherapy (HR, 15.65; 95% CI, 3.63 to 67.53; P < .001).

CONCLUSION

CTCs are detectable in patients with stage IV NSCLC and are a novel prognostic factor for this disease. Further validation is warranted before routine clinical application.

Scan? Cure? Sure!

Presentation of The Case

A 61-year-old man undergoes a sigmoid colectomy for a T3N1 (two of 18 nodes) adenocarcinoma of the sigmoid colon. He recovers well and receives 6 months of adjuvant FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) uneventfully. At his first follow-up visit, the oncologist recommended every 3 month visits for a physical, liver function tests, and carcinoembryonic antigen (CEA) measurement; every 6 month chest, abdomen, and pelvic computed tomography (CT) scans for 3 years; and aspirin, vitamin D supplementation, and exercise. Is CT scanning appropriate in the follow-up of colon cancer patients? (This case was presented at Massachusetts General Hospital Cancer Center.)

Circulating tumor cells in colorectal cancer: past, present, and future challenges

Recent advances in immunomagnetic separation and flow cytometry have made the detection and characterization of circulating tumor cells (CTC) a reality. This technology has already demonstrated prognostic significance in breast and prostate cancer. In the current review, we will review the historical and current data regarding the enumeration and identification of CTC in colorectal cancer. With immunomagnetic separation techniques, CTC can reliably and reproducibly be identified within 1 to 2 cells in a 7.5 mL sample of peripheral blood. Prospective studies have demonstrated a significant adverse impact on survival with the presence of > or = 3 CTC per 7.5 mL blood. Approximately one quarter of patients with metastatic disease will be categorized in this poor prognosis group. In addition, change in number of cells on treatment has prognostic significance. While CTC enumerated through immunomagnetic separation are a clear prognostic factor for patients with mCRC, the future challenge is to study whether treatment decision-making should be impacted by their level. Low cell yield in mCRC is a potential hinderance to answering these important clinical questions at present. CTC can also be isolated and studied with flow cytometry, FISH, and RT-PCR, allowing real-time assessment of tumor biology. Future advances in this field will improve both the detection and manipulation of these cells. Improvements in detection and characterization of CTC will hopefully lead to refinement of the surgical and chemotherapeutic treatment of colorectal cancer.

Circulating Tumor Cells and Colorectal Cancer

The significance of circulating tumor cells (CTCs) has been discussed for more than a century. The advent of modern technology has allowed for more reliable detection of CTCs, and recent studies have provided compelling evidence that CTCs predict clinical response in metastatic colorectal cancer (mCRC). Combination of CTC analysis with independent prognostic factors has demonstrated powerful synergy in some studies. The ability of CTCs to predict metastasis and therapy-specific response has high potential clinical utility, with early studies showing promising results in colorectal cancer (CRC). Reliable CTC detection has also allowed for examination of tumor cell dissemination during surgery, and there appears to be a heavy dependence on the approach chosen. This review discusses the evidence for CTC significance, with particular focus on detection methods, novel markers, and clinical outcomes in CRC. Numerous opportunities exist for preclinical, clinical, and translational studies to explore molecular determinants within CTCs, as well as the value of CTCs in directing targeted therapeutics.

All circulating EpCAM+CK+CD45- objects predict overall survival in castration-resistant prostate cancer

BACKGROUND

Presence of five or more circulating tumor cells (CTC) in patients with metastatic carcinomas is associated with poor survival. Although many objects positive for epithelial cell adhesion molecules and cytokeratin (EpCAM+CK+) are not counted as CTC, they may be an important predictor for survival. We evaluated the association between these objects and survival in patients with prostate cancer.

PATIENTS AND METHODS

Included in this follow-up study were 179 patients with castration-resistant prostate cancer. CellSearch was used to isolate EpCAM+ objects and to stain DNA, cytokeratin and CD45. All EpCAM+CK+ objects were subdivided into seven classes on the basis of predefined morphological appearance in 63 independent samples. Association of each class with survival was studied using Kaplan-Meier and Cox regression analyses.

RESULTS

Each EpCAM+CK+CD45- class showed a strong association with overall survival (P < 0.001). This included small tumor microparticles (S-TMP), which did not require a nucleus and thus are unable to metastasize. A higher number of objects in any class was associated with decreased survival. A good prediction model included large tumor cell fragments (L-TCF), age, hemoglobin and lactate dehydrogenase. Models with S-TMP or CTC instead of L-TCF performed similarly.

CONCLUSION

EpCAM+CK+CD45- that do not meet strict definitions for CTC are strong prognostic markers for survival.

Detection of circulating tumor cells: recent progress in clinical applications

During the process of cancer metastasis, some cancer cells, termed circulating tumor cells (CTCs), are liberated from primary tumor tissue. New techniques have been developed to isolate and characterize these cells. The early detection of CTCs represents not only a powerful diagnostic tool for cancer but also an important predictive and prognostic marker for evaluation of disease progression and treatment response. In this article, we discuss the clinical utility of CTCs detection in breast, prostate, and colon cancer, and explore the future directions in this field.

Circulating tumor cells in metastatic colorectal cancer: efficacy and feasibility of different enrichment methods

Comprehensive in vitro and in vivo studies comparing EpCAM-based methods with other cytometric CTC enrichment technologies in metastatic colorectal cancer (mCRC) patients are lacking. We compare four manual cytometric methods to detect CTCs in vitro and in mCRC patients. The EpCAM-based technology, MACS HEA MicroBeads((R)), showed a significant better tumor cell recovery rate compared to other cytometric methods (p-value<0.0001). CTCs of 38 mCRC patients were enriched with MACS HEA MicroBeads(R). Progression-free survival did significantly differ between mCRC patients without detectable and with >or= 1 CTCs (p=0.007). CTC enrichment with EpCAM coupled antibodies is superior to other cytometric methods and is a feasible method for CTC detection in mCRC patients.

Clinical relevance associated to the analysis of circulating tumour cells in patients with solid tumours

The distant growth of tumour cells escaping from primary tumours, a process termed metastasis, represents the leading cause of death among patients affected by malignant neoplasias from breast and colon. During the metastasis process, cancer cells liberated from primary tumour tissue, also termed circulating tumour cells (CTCs), travel through the circulatory and/or lymphatic systems to reach distant organs. The early detection and the genotypic and phenotypic characterisation of such CTCs could represent a powerful diagnostic tool of the disease, and could also be considered an important predictive and prognostic marker of disease progression and treatment response. In this article we discuss the potential relevance in the clinic of monitoring CTCs from patients suffering from solid epithelial tumours, with emphasis on the impact of such analyses as a predictive marker for treatment response.

Circulating tumor cells

Circulating tumor cells (CTCs) can be separated and characterized from normal hematopoietic cellular constituents by a variety of methods. Different strategies have included separation by physical characteristics, such as size or weight, or by biological characteristics, such as expression of epithelial or cancer-specific markers. Of the latter, rtPCR for epithelial-related gene message, such as cytokeratin, and immunoseparation techniques using monoclonal antibodies against epithelial cellular adhesion molecule, have gained the most widespread use in investigational and standard clinical application to date. Detection and monitoring of CTCs might be useful for screening, prognosis, prediction of response to therapy, or monitoring clinical course in patients with primary or metastatic cancer. Currently, monitoring patients with metastatic disease is the most practical application of CTCs. In this regard, several studies have demonstrated that approximately 50-70% of patients with metastatic breast, colon, and prostate cancers have elevated CTC levels, when evaluated using a highly automated immunomagnetic CTC assay system, designated CellSearch®. These studies demonstrate that elevated CTC levels prior to initiation of a new systemic therapy are associated with a worse prognosis than those that do not, and that persistently elevated or subsequent rising CTC levels strongly suggest that the therapeutic regimen with which the patient is being treated is not working. Similar results have been shown with rtPCR assays, although they are not as widely available for routine clinical use. New areas of research are directed toward developing more sensitive means of CTC detection and generating a variety of methods to characterize the molecular and biologic nature of CTCs, such as the status of hormone receptors, epidermal, and other growth factor receptor family members, and indications of stem-cell characteristics.

The presence of circulating tumor cells does not predict extravesical disease in bladder cancer patients prior to radical cystectomy

OBJECTIVE

Due to imprecise clinical staging, the finding of extravesical and node-positive disease at the time of radical cystectomy (RC) for patients with clinically localized bladder cancer is not uncommon. Circulating tumor cells (CTCs) have been shown to be present in the peripheral blood of patients with metastatic urothelial carcinoma. The object of this study was to evaluate the ability of CTCs to predict extravesical disease in bladder cancer patients prior to RC.

MATERIALS AND METHODS

Peripheral blood samples from 43 patients with bladder cancer were evaluated using the CellSearch (Veridex, LLC, Raritan, NJ) CTC assay prior to RC. The sensitivity, specificity, and positive predictive value (PPV) of CTC status in predicting extravesical disease was calculated. Receiver operating characteristic (ROC) curves were generated to quantify the ability of CTCs to predict extravesical and node-positive disease.

RESULTS

CTCs were detected in 9 (21%) patients prior to RC. The sensitivity, specificity, and PPV of CTC status in predicting extravesical disease were 27%, 88% and 78%, respectively. The accuracy of CTC status in predicting extravesical (≥pT3 or node-positive) disease for the entire cohort was 0.576. In a model incorporating preoperative hydronephrosis, CTC status did not improve the predictive accuracy for extravesical disease (0.576 vs. 0.585, P = 0.915).

CONCLUSION

CTCs were detected in low numbers in a small percentage (21%) of patients prior to undergoing RC at our institution. CTC status was not a robust predictor of extravesical or node-positive disease in this cohort. CTC status is not likely to be a clinically useful parameter for directing therapeutic decisions in patients with ≤cT2 bladder cancer.

Significance of Circulating Tumor Cells Detected by the CellSearch System in Patients with Metastatic Breast Colorectal and Prostate Cancer

The increasing number of treatment options for patients with metastatic carcinomas has created a concomitant need for new methods to monitor their use. Ideally, these modalities would be noninvasive, be independent of treatment, and provide quantitative real-time analysis of tumor activity in a variety of carcinomas. Assessment of circulating tumor cells (CTCs) shed into the blood during metastasis may satisfy this need. We developed the CellSearch System to enumerate CTC from 7.5 mL of venous blood. In this review we compare the outcomes from three prospective multicenter studies investigating the use of CTC to monitor patients undergoing treatment for metastatic breast (MBC), colorectal (MCRC), or prostate cancer (MPC) and review the CTC definition used in these studies. Evaluation of CTC at anytime during the course of disease allows assessment of patient prognosis and is predictive of overall survival.

Modeling the relationship between circulating tumour cells number and prognosis of metastatic breast cancer

Circulating tumor cell (CTC) count has been shown to be an independent predictor of progression in metastatic breast, prostate, and colorectal cancer. A cutpoint is generally used to identify favorable and unfavorable response groups. In this study, we propose an approach in which the number of CTCs is analyzed as a continuous predictor, to detect the shape of the relationship between CTCs and prognosis of metastatic breast cancer. We evaluated the association of baseline CTC with progression-free survival (PFS) and overall survival (OS) in a series of 80 patients treated for advanced breast cancer at the European Institute of Oncology, Milan. The association between CTCs and prognosis was analyzed with standard categorical survival analysis and spline regression models. At baseline, median age was 55 years; 33 patients were newly diagnosed with metastatic breast cancer (41%), while 28 (35%) and 19 (24%) were pretreated with one and two previous chemotherapy lines, respectively. After a median follow-up of 28 months, 76 disease progressions and 44 deaths were observed. Kaplan-Meier curves showed a clear association between CTCs and PFS (P-value 0.03) and OS (P-value < 0.01). Patients with no CTC at baseline had a significantly better prognosis. When analyzing the CTCs as a continuous variable, we found an increase in risk with increasing number of CTCs, for both PFS and OS. The increase rate lessened after approximately 5 CTCs. CTCs represent a robust prognostic factor in the metastatic breast cancer setting. A nonlinear increase in risk of both progression and death with increasing number of CTCs was observed, with a lessening increase after approximately 5 CTCs. If distinct prognostic groups are to be identified, women with no CTC could plausibly represent a distinct favorable one.

Circulating tumor cells: evolving evidence and future challenges

Circulating tumor cells (CTCs) are rare malignant cells found in the peripheral blood that originate from the primary tumor or metastatic sites. New techniques have been developed to isolate and characterize these cells. CTC enumeration has been incorporated into different fields of oncology as a prognostic marker, a tool to monitor therapy response, and a method to understand basic tumor characteristics. This review covers the different techniques available for isolation of CTCs, the clinical utility of CTCs in breast, prostate, and colon cancer, and future directions in this field.

Circulating tumor cells in gastrointestinal malignancies: current techniques and clinical implications

Since their introduction more than 50 years by Engell, circulating tumor cells (CTCs) have been evaluated in cancer patients and their detection has been correlated with clinical outcome, in esophageal, gastric, and colorectal cancer. With the availability of refined technologies, the identification of CTCs from peripheral blood is emerging as a useful tool for the detection of malignancy, monitoring disease progression, and measuring response to therapy. However, increasing evidence suggests a variety of factors to be responsible for disease progression. The analysis of a single CTC marker is therefore unlikely to accurately predict progression of disease with sufficient resolution and reproducibility. Here we discuss the current concept of CTCs, summarize the available techniques for their detection and characterization, and aim to provide a comprehensive update on the clinical implications of CTCs in gastrointestinal (GI) malignancies.

Circulating tumour cells early predict progression-free and overall survival in advanced colorectal cancer patients treated with chemotherapy and targeted agents

BACKGROUND

Early predictive markers for response are needed for advanced colorectal cancer (ACC) patients. We assessed the value of circulating tumour cells (CTC) in ACC patients treated with chemotherapy plus targeted agents (CAIRO2 phase III trial) and compared the results with computed tomography (CT) imaging.

MATERIALS AND METHODS

CTC were determined at baseline and at different time points during treatment. Patients were stratified into low (less than three CTC per 7.5 ml of blood) or high CTC (three or more CTC per 7.5 ml of blood).

RESULTS

A total of 467 patients were assessable for CTC analysis. Among them, 129 patients (29%) with high baseline CTC had a significantly decreased progression-free survival [PFS; hazard ratio (HR) 1.5] and overall survival (OS; HR 2.2) compared with 322 patients with low baseline CTC. This difference remained statistically significant during treatment. The sensitivity and specificity of high CTC at baseline for the prediction of progressive disease on CT imaging were 16.7% and 70.1%, respectively, and of high CTC at 1-2 weeks after the start of treatment 20.0% and 95.1%, respectively. The combined analysis of CTC and CT imaging provided a more accurate outcome assessment than either modality alone.

CONCLUSIONS

The CTC count before and during treatment independently predicts PFS and OS in ACC patients treated with chemotherapy plus targeted agents and provides additional information to CT imaging.