Immunomagnetic Quantification of Circulating Tumor Cells as a Prognostic Factor of Androgen Deprivation Responsiveness in Patients With Hormone Naive Metastatic Prostate Cancer

Metastatic hormone-naïve prostate cancer: a distinct biological entity

Metastatic hormone-naïve prostate cancer (mHNPC) is often the initial form of presentation for metastatic prostate cancer and encompasses a heterogeneous patient population with high inter-patient heterogeneity in prognosis and response to therapy. A more precise treatment of mHNPC, guided by evidence-based biomarkers, remains an unmet medical need. In addition, the limited number of representative laboratory models of mHNPC hampers the translation of basic research into clinical applications. We provide a comprehensive overview of the clinical and biological features that characterize mHNPC, highlight molecular data that could explain the unique prognostic characteristics of mHNPC, and identify key open questions.

Perioperative change of circulating tumor cells in cytoreductive radical prostatectomy for oligometastatic hormone-sensitive prostate cancer: the preliminary safety evidence from long-term oncologic outcomes

Surgical manipulation has a risk of triggering the shedding of circulating tumor cells (CTCs) in patients with malignancies, However, perioperative change of circulating tumor cells in cytoreductive radical prostatectomy (CRP) for patients with oligometastatic hormone-sensitive prostate cancer (omHSPC) has not yet been well documented. This study aimed to assess whether CRP is a safe procedure for patients with omHSPC by monitoring the perioperative change of CTCs and investigating its impact on long-term oncologic outcomes. We have observed a significant decrease between the median CTC counts before and after surgery (6 vs. 4, p = 0.026). Comparing preoperative and postoperative CTC levels, seven patients increased (CTC increase group), one did not change and nineteen decreased (CTC non-increase group). PSA response rates in CTC increase group were lower than those in CTC non-increase group (73.0% vs 99.8%, p = 0.162), and nadir PSA was higher in CTC increase group (0.043 vs 0.003, p = 0.072). The CTC increase was positively correlated with the nadir PSA (r = 0.386, p = 0.047). The median follow-up period was 71.6 months, we found that there was no significant difference in clinical-pathological, operative variables or long-term oncologic outcomes between perioperative CTC increase and non-increase groups. In the entire cohort, the CTC level significantly decreased after surgery. There was no significant differences in long-term oncologic outcomes between the CTC increase and non-increase groups, implying that CRP potentially represents a safe procedure for the treatment of patients with omHSPC. The results need to be confirmed in a prospective large-scale clinical trial.

Nurturing the marriages of urinary liquid biopsies and nano-diagnostics for precision urinalysis of prostate cancer

Prostate cancer remains the second-most common cancer diagnosed in men, despite the increasingly widespread use of serum prostate-specific antigen (PSA) screening. The controversial clinical implications and cost benefits of PSA screening have been highlighted due to its poor specificity, resulting in a high rate of overdiagnosis and underdiagnosis. Thus, the development of novel biomarkers for prostate cancer detection remains an intriguing challenge. Urine is emerging as a source for prostate cancer biomarker discovery. Currently, new urine biomarkers already outperform serum PSA in clinical diagnosis. Meanwhile, the advances in nanotechnology have provided a suite of diagnostic tools to study prostate cancer in more detail, sparking a new era of biomarker discoveries. In this review, we envision that future prostate cancer diagnosis will probably integrate multiplex nano-diagnostic approaches to detect novel urinary biomarkers. However, challenges remain in differentiating indolent from aggressive cancers to better inform treatment decisions, and clinical translation still needs to be overcome.

Overcoming Obstacles in Liquid Biopsy Developments for Prostate Cancer

Prostate cancer is one of the most common malignancies in men. Over time, it can metastasize and become lethal once it exhausts hormonal therapies and transitions into castration-resistant prostate cancer (CRPC). Several therapies have been recently approved for advanced prostate cancer, but identifying biomarkers for current treatments and searching for more effective treatments are urgently needed. Liquid biopsy is a powerful tool for isolating genetic material, proteins, and whole tumor cells from the blood. In recent decades, this technology has rapidly advanced, allowing for better insights into the pathogenesis and treatment response in different stages of prostate cancer. In this review, we summarize important clinical studies involving liquid biopsies in prostate cancer with a focus on advanced disease, notably regarding circulating tumor DNA, circulating tumor cells, and exosomes. We highlight the progress and the challenges that still exist for these technologies. Finally, we discuss promising avenues that will further expand the importance of liquid biopsy in the care for prostate cancer patients.

Presence of CD133-positive circulating tumor cells predicts worse progression-free survival in patients with metastatic castration-sensitive prostate cancer

Objective

To investigate the clinical significance of the expression of the stemness marker CD133 in circulating tumor cells of newly diagnosed metastatic castration‐sensitive prostate cancer patients.

Methods

For this study, 104 metastatic castration‐sensitive prostate cancer patients treated at the Fudan University Shanghai Cancer Center from September 2015 to February 2017 were considered. After enrollment, the patients received androgen deprivation therapy (bicalutamide + goserelin). Circulating tumor cells were isolated and identified using the CanPatrol system, which can identify not only traditional epithelial markers but also mesenchymal markers in cells that have undergone epithelial mesenchymal transition. CD133 was used to characterize the circulating tumor cells. The primary endpoint of this research was to evaluate progression to castration resistance.

Results

Among the 104 patients enrolled, 89 patients were circulating tumor cell positive at baseline, and the median circulating tumor cell count was four. The median follow‐up was 24 months, and at the end of follow‐up, the proportion of patients who progressed to castration‐resistant prostate cancer in the CTC+CD133+ group was 93.3%, which was significantly higher than that of the circulating tumor cell negative group (73.3%) and the CTC+CD133− group (75.0%), with P = 0.043. After follow‐up, progression‐free survival for CTC+CD133+, CTC+CD133−, and circulating tumor cell patients was 10.0, 13.0, and 14.0 months, respectively, with P = 0.022. Univariate and multivariate analyses also confirmed that the characterization of circulating tumor cells using CD133 can independently predict progression‐free survival in metastatic castration‐sensitive prostate cancer patients after receiving androgen deprivation therapy (P = 0.042; hazard ratio 1.396).

Conclusion

Baseline CTC+CD133+ was a poor independent prognostic factor for metastatic castration‐sensitive prostate cancer patients to progress to castration‐resistant prostate cancer after receiving androgen deprivation therapy.

Multigene Profiling of Circulating Tumor Cells (CTCs) for Prognostic Assessment in Treatment-Naïve Metastatic Hormone-Sensitive Prostate Cancer (mHSPC)

The substantial biological heterogeneity of metastatic prostate cancer has hindered the development of personalized therapeutic approaches. Therefore, it is difficult to predict the course of metastatic hormone-sensitive prostate cancer (mHSPC), with some men remaining on first-line androgen deprivation therapy (ADT) for several years while others progress more rapidly. Improving our ability to risk-stratify patients would allow for the optimization of systemic therapies and support the development of stratified prospective clinical trials focused on patients likely to have the greatest potential benefit. Here, we applied a liquid biopsy approach to identify clinically relevant, blood-based prognostic biomarkers in patients with mHSPC. Gene expression indicating the presence of CTCs was greater in CHAARTED high-volume (HV) patients (52% CTC_high) than in low-volume (LV) patients (23% CTC_high; * p = 0.03). HV disease (p = 0.005, q = 0.033) and CTC presence at baseline prior to treatment initiation (p = 0.008, q = 0.033) were found to be independently associated with the risk of nonresponse at 7 months. The pooled gene expression from CTCs of pre-ADT samples found AR, DSG2, KLK3, MDK, and PCA3 as genes predictive of nonresponse. These observations support the utility of liquid biomarker approaches to identify patients with poor initial response. This approach could facilitate more precise treatment intensification in the highest risk patients.

Clinical Relevance of Circulating Tumor Cells in Prostate Cancer Management

Given the low specificity of the routinely used biomarker prostate-specific antigen, circulating tumor cell (CTC) enumeration seems to be particularly useful in the monitoring of prostate cancer. In this review, we focused on a few aspects of CTC enumeration in prostate malignancies: prognostic value in metastatic and non-metastatic tumors, role in the monitoring of treatment outcomes, use as a surrogate marker for survival, and other applications, mostly for research purposes. CTC enumeration, without a doubt, offers an attractive perspective in the management of prostate cancer. However, the vast majority of available data about the role of CTC in this malignancy originate from randomized studies of anticancer agents and do not necessarily translate into real-world clinical practice. Further, most studies on the application of CTC in prostate cancer patients were limited to advanced stages of this malignancy. Meanwhile, the role of CTC in the early stages of prostate cancer, in which some patients may present with occult disseminated disease, is still relatively poorly understood, and should thus be studied extensively. Other obstacles in the widespread application of CTC enumeration in routine clinical practice include considerable discrepancies in the number of cells determined with various commercially available systems.

Baseline Circulating Tumor Cell Count as a Prognostic Marker of PSA Response and Disease Progression in Metastatic Castrate-Sensitive Prostate Cancer (SWOG S1216)

PURPOSE

In metastatic castrate-sensitive prostate cancer (mCSPC), combined androgen axis inhibition is a standard of care. Noninvasive biomarkers that guide initial therapy decisions are needed. We hypothesized that CellSearch circulating tumor cell (CTC) count, an FDA-cleared assay in metastatic castrate-resistant prostate cancer (mCRPC), is a relevant biomarker in mCSPC.

EXPERIMENTAL DESIGN

SWOG S1216 is a phase III prospective randomized trial of androgen deprivation therapy (ADT) combined with orteronel or bicalutamide for mCSPC. CellSearch CTC count was measured at registration (baseline). Prespecified CTC cut-off points of 0, 1-4, and ≥5 were correlated with baseline patient characteristics and, in a stratified subsample, were also correlated with two prespecified trial secondary endpoints: 7-month PSA ≤0.2 ng/mL versus 0.2-4.0 versus >4.0 (intermediate endpoint for overall survival); and progression-free survival (PFS) ≤ versus >2 years.

RESULTS

A total of 523 patients submitted baseline samples, and CTCs were detected (median 3) in 33%. Adjusting for two trial stratification factors (disease burden and timing of ADT initiation), men with undetectable CTCs had nearly nine times the odds of attaining 7-month PSA ≤ 0.2 versus > 4.0 [OR 8.8, 95% confidence interval (CI), 2.7-28.6, P < 0.001, N = 264] and four times the odds of achieving > 2 years PFS (OR 4.0, 95% CI, 1.9-8.5, P < 0.001, N = 336) compared with men with baseline CTCs ≥5.

CONCLUSIONS

Baseline CTC count in mCSPC is highly prognostic of 7-month PSA and 2-year PFS after adjusting for disease burden and discriminates men who are likely to experience poor survival outcomes.

Increased tumor-associated macrophages in the prostate cancer microenvironment predicted patients' survival and responses to androgen deprivation therapies in Indonesian patients cohort

BACKGROUND

Tumor-associated macrophages (TAMs) and microvessel density (MVD) play an essential role for tumor progression in prostate cancer (PCa). In this study, we evaluated the association between TAMs, the infiltration with tumor angiogenesis and the response to androgen deprivation therapies (ADTs) in PCa to evaluate TAM infiltration as a predictive factor for PCa survival.

MATERIALS AND METHODS

Fifty-four specimens were collected and stained with CD 68 antibody to investigated TAM infiltration in tumor. Von Willebrand factor was stained to evaluate MVD around the cancer foci. We assessed the association between patient's age, preoperative serum prostate-specific antigen, pathologic Gleason sum (GS), TAM infiltration, MVD, and the response to ADT for 5 years after PCa diagnosis.

RESULTS

The median TAM was observed in 28 (6-76)/high power field (x400). Increasing TAM correlated with increasing tumor angiogenesis (P < 0.001, r = 0.61), and the response to ADT was significantly better in patients with fewer TAMs (<28) than in patients with higher TAMs (>28) (P = 0.003). TAM infiltration was significantly higher in those with higher serum prostate-specific antigen, higher GS, and metastasis. Multivariate analysis showed that GS, ADT type, and MVD number were significant prognostic factors for response to ADT in PCa (P < 0.0001). An increased infiltration of TAM [hazards ratio (HR) = 4.47; 95% confidence interval (CI): 1.97-10.15], MVD (HR = 2.66; 95% CI: 1.27-5.61), metastatic status (HR = 2.29; 95% CI: 0.14-0.60), and prostate volume (HR = 2.19; 95% CI: 1.27-3.12) significantly correlated with shorter survival in PCa patients by univariate analysis (P < 0.05). Multivariate analyses revealed that TAM and metastatic status significantly correlated with poor overall survival.

CONCLUSIONS

TAM infiltration is associated with response to ADT and increased tumor angiogenesis in PCa. GS, ADT type, and MVD in PCa specimens are useful predictive factors for poor response to ADT. Increasing TAM and positive metastatic status were prognostic factors for a poorer survival in PCa patients.

The biology and clinical potential of circulating tumor cells

Background Tumor cells can shed from the tumor, enter the circulation and travel to distant organs, where they can seed metastases. These cells are called circulating tumor cells (CTCs). The ability of CTCs to populate distant tissues and organs has led us to believe they are the primary cause of cancer metastasis. The biological properties and interaction of CTCs with other cell types during intravasation, circulation in the bloodstream, extravasation and colonization are multifaceted and include changes of CTC phenotypes that are regulated by many signaling molecules, including cytokines and chemokines. Considering a sample is readily accessible by a simple blood draw, monitoring CTC levels in the blood has exceptional implications in oncology field. A method called the liquid biopsy allows the extraction of not only CTC, but also CTC products, such as cell free DNA (cfDNA), cell free RNA (cfRNA), microRNA (miRNA) and exosomes. Conclusions The clinical utility of CTCs and their products is increasing with advances in liquid biopsy technology. Clinical applications of liquid biopsy to detect CTCs and their products are numerous and could be used for screening of the presence of the cancer in the general population, as well as for prognostic and predictive biomarkers in cancer patients. With the development of better CTC isolation technologies and clinical testing in large prospective trials, increasing clinical utility of CTCs can be expected. The understanding of their biology and interactions with other cell types, particularly with those of the immune system and the rise of immunotherapy also hold great promise for novel therapeutic possibilities.

Phenotypes of circulating tumour cells predict time to castration resistance in metastatic castration-sensitive prostate cancer

OBJECTIVES

To identify biomarkers that predict the response to standard androgen deprivation therapy (ADT) of patients newly diagnosed with metastatic castration-sensitive prostate cancer (CSPC) in order to improve therapeutic decision-making, and to investigate whether the characterization of baseline circulating tumour cells (CTCs) would predict the effective period of standard ADT.

MATERIALS AND METHODS

The study included 108 patients newly diagnosed with high-volume metastatic CSPC. Enumeration and characterization of patients' baseline CTCs (CTCs+ and CTCs-, indicating detectable and undetectable CTCs, respectively) were performed using the CanPatrol technique, which detects markers of the epithelial to mesenchymal transition (EMT) in CTCs, and classifies CTCs into epithelial, biophenotypic and mesenchymal phenotypes.

RESULTS

After a median follow-up of 24 months, 90 patients (83.3%) progressed to castration-resistant prostate cancer (CRPC), 93 patients (86.1%) had detectable CTCs, and the median number of CTCs was 4. The rate of progression to CRPC was significantly higher for patients with mesenchymal CTCs+ than for patients with CTCs+/mesenchymal CTCs- and CTCs- (93.1% vs 71.4% and 73.3%; P = 0.013). The median time to CRPC for patients with mesenchymal CTCs+ was significantly shorter than for those with CTCs+/mesenchymal CTCs- and CTCs- (10.5 months vs 18.0 and 14.0 months; P = 0.003). Multivariate Cox regression analysis suggested that the CTC phenotype was the only independent prognostic factor influencing the progression of disease from CSPC to CRPC.

CONCLUSIONS

Characterization of baseline CTCs according to the EMT phenotype predicted the effective period of standard ADT for patients newly diagnosed with metastatic CSPC. These findings are important for counselling patients and designing clinical trials.

Initial detection of circulating tumor cells from metastatic prostate cancer patients with a novel small device

Background

Various devices for isolating and detecting circulating tumor cells (CTCs) have been developed, whereas the CellSearch® system has been clinically used in numerous prostate CTC studies. CTCs might become more useful surrogate markers of prostate cancer, and they should be measured in all settings, but a smaller, low-cost CTC capture system is required.

Methods

An inexpensive and highly sensitive microfluidic CTC-capture polymeric chip, developed by the Toyama Industrial Technology Center, as described in the following text, was used to assess the number of CTCs from patients with metastatic prostate cancer. After verifying that cultured human prostate cancer cells (PC3 and LNCaP) could be captured with the chip coated with anti–epithelial cell adhesion molecule (CD326) antibody, whole blood samples of 14 patients with prostate cancer were screened.

Results

The average capture efficacy of PC3 cells was 94.60% in phosphate-buffered saline (PBS) and 83.82% in whole blood. The average capture efficacy of LNCaP cells was 82.73% in PBS and 75.78% in whole blood. CTCs were detected by the chip device in all 14 patients with metastatic prostate cancer using 2-mL blood samples. Although fewer CTCs were detected in patients with oligometastases, all patients with multiple distant metastases had CTCs. The average CTC count was 48 cells/mL (range 1–81 cells/mL).

Conclusion

This CTC-chip will be able to capture CTCs and be useful to check CTCs as a surrogate marker in prostate cancer with smaller samples and lower cost in any small institution.

Circulating Tumor Cells in Prostate Cancer: From Discovery to Clinical Utility

BACKGROUND

Prostate cancer represents the most common non–skin cancer type in men. Unmet needs include understanding prognosis to determine when intervention is needed and what type, prediction to guide the choice of a systemic therapy, and response indicators to determine whether a treatment is working. Over the past decade, the “liquid biopsy,” characterized by the analysis of tumor cells and tumor cell products such as cell-free nucleic acids (DNA, microRNA) or extracellular vesicles circulating in the blood of cancer patients, has received considerable attention.

CONTENT

Among those biomarkers, circulating tumor cells (CTCs) have been most intensively analyzed in prostate cancer. Here we discuss recent studies on the enumeration and characterization of CTCs in peripheral blood and how this information can be used to develop biomarkers for each of these clinical contexts. We focus on clinical applications in men with metastatic castration-resistant prostate cancer, in whom CTCs are more often detected and at higher numbers, and clinical validation for different contexts of use is most mature.

SUMMARY

The overall goal of CTC-based liquid biopsy testing is to better inform medical decision-making so that patient outcomes are improved.

Clinical applications of the CellSearch platform in cancer patients

The CellSearch® system (CS) enables standardized enrichment and enumeration of circulating tumor cells (CTCs) that are repeatedly assessable via non-invasive "liquid biopsy". While the association of CTCs with poor clinical outcome for cancer patients has clearly been demonstrated in numerous clinical studies, utilizing CTCs for the identification of therapeutic targets, stratification of patients for targeted therapies and uncovering mechanisms of resistance is still under investigation. Here, we comprehensively review the current benefits and drawbacks of clinical CTC analyses for patients with metastatic and non-metastatic tumors. Furthermore, the review focuses on approaches beyond CTC enumeration that aim to uncover therapeutically relevant antigens, genomic aberrations, transcriptional profiles and epigenetic alterations of CTCs at a single cell level. This characterization of CTCs may shed light on the heterogeneity and genomic landscapes of malignant tumors, an understanding of which is highly important for the development of new therapeutic strategies.

Liquid Biopsy in Prostate Cancer: Circulating Tumor Cells and Beyond

Prostate cancer is a common malignancy impacting countless men without curative options in the advanced state. Numerous therapies have been introduced in recent years improving survival and symptom control, yet optimal methods for predicting or monitoring response have not been developed. In the era of precision medicine, characterization of individual cancers is necessary to inform treatment decisions. Liquid biopsies, through evaluation of various blood-based analytes, provide a method of patient evaluation with potential applications in virtually all disease states. In this review, we will describe current approaches with a particular focus on demonstrated clinical utility in the evaluation and management of prostate cancer.

The evolution of chemotherapy for the treatment of prostate cancer

Chemotherapy has been explored as a treatment option for metastatic prostate cancer since the early 1980s. Docetaxel, a taxane chemotherapeutic, was approved for the treatment of men with metastatic castration-resistant prostate cancer in 2004, and is now standard of care for late stage disease. Recent clinical studies demonstrated that patients with metastatic castration-sensitive disease, and possibly those with high-risk localized prostate cancer also benefit from docetaxel administration, expanding the role of chemotherapy in the prostate cancer treatment landscape. Another taxane, cabazitaxel, is approved for post-docetaxel metastatic castration-resistant prostate cancer. Taxanes and other chemotherapeutics, such as carboplatin, are now being tested in combination regimens. This review presents an outline of recent and ongoing clinical studies assessing docetaxel and its derivative cabazitaxel at different stages of the disease, and in various combinations with other agents. We summarize current knowledge on biomarkers predictive of response to chemotherapy, which may in future be used to guide individualized treatment decisions.

Circulating Tumor Cells as a Marker for Progression-free Survival in Metastatic Castration-naïve Prostate Cancer

BACKGROUND

Analysis of circulating tumor cells (CTC) is a promising prognostic marker in castration-resistant prostate cancer (CRPC). The aim of this study was to investigate CTC detection and phenotyping as prognostic biomarkers for response to primary androgen deprivation therapy (ADT) of metastatic prostate cancer (PC).

METHODS

PC patients presenting with a prostate specific antigen (PSA) >80 ng/ml and/or metastatic disease, intended for ADT were enrolled in the study. CTCs were analysed for expression of PSA prostate specific membrane antigen (PSMA) and epidermal growth factor receptor (EGFR) before and three months after ADT and related to progression.

RESULTS

At inclusion, 46 out of 53 patients (87%) were CTC-positive with a sensitivity and specificity for distant metastases (M1) of 98% and 75%, respectively. In patients with M1-disease, EGFR-detection in CTC was an independent prognostic marker for progression-free survival, whereas PSA and alkaline phosphatase serum levels, Gleason score, or T-stage were not. EGFR-positive patients had significantly shorter time to progression (5 months) compared to EGFR-negative patients (11 months) (P < 0.05).

CONCLUSIONS

In this explorative study, CTCs were detected in 98% of M1 patients and detection of EGFR in CTCs was strongly associated with poor outcome, which indicated that phenotypical analysis of CTC could be a promising prognostic marker of ADT-response in castration-naïve metastatic PC patients. Prostate 77:849-858, 2017. © 2017 Wiley Periodicals, Inc.

Circulating Tumor Cells in Genitourinary Malignancies: An Evolving Path to Precision Medicine

Precision medicine with molecularly directed therapeutics is rapidly expanding in all subspecialties of oncology. Molecular analysis and treatment monitoring require tumor tissue, but resections or biopsies are not always feasible due to tumor location, patient safety, and cost. Circulating tumor cells (CTCs) offer a safe, low-cost, and repeatable tissue source as an alternative to invasive biopsies. "Liquid biopsies" can be collected from a peripheral blood draw and analyzed to isolate, enumerate, and molecularly characterize CTCs. While there is deserved excitement surrounding new CTC technologies, studies are ongoing to determine whether these cells can provide reliable and accurate information about molecular drivers of cancer progression and inform treatment decisions. This review focuses on the current status of CTCs in genitourinary (GU) cancer. We will review currently used methodologies to isolate and detect CTCs, their use as predictive biomarkers, and highlight emerging research and applications of CTC analysis in GU malignancies.

Epidermal Growth Factor Receptor Status in Circulating Tumor Cells as a Predictive Biomarker of Sensitivity in Castration-Resistant Prostate Cancer Patients Treated with Docetaxel Chemotherapy

Objective: We examined whether epidermal growth factor receptor (EGFR) expression in circulating tumor cells (CTCs) can be used to predict survival in a population of bone-metastatic castration-resistant prostate cancer (mCRPC) patients treated with docetaxel chemotherapy. Methods: All patients with mCRPC who had experienced treatment failure with androgen-deprivation therapy and had received docetaxel chemotherapy were eligible. CTCs and EGFR expression in CTCs were enumerated with the CellSearch System in whole blood. This system is a semi-automated system that detects and enriches epithelial cells from whole blood using an EpCAM antibody-based immunomagnetic capture. In addition, the EGFR-positive CTCs were assessed using CellSearch^® Tumor Phenotyping Reagent EGFR. Results: The median CTC count at baseline before starting trial treatment was eight CTCs per 7.5 mL of blood (range 0–184). There were 37 patients (61.7%) who had ≥5 CTCs, with median overall survival of 11.5 months compared with 20.0 months for 23 patients (38.3%) with <5 CTCs (p < 0.001). A total of 15 patients (40.5%, 15/37) with five or more CTCs were subjected to automated immunofluorescence staining and cell sorting for EGFR protein. Patients with EGFR-positive CTCs had a shorter overall survival (OS) (5.5 months) than patients with EGFR-negative CTCs (20.0 months). CTCs, EGFR-positive CTCs, and alkaline phosphatase (ALP) were independent predictors of overall survival time (p = 0.002, p < 0.001, and p = 0.017, respectively). Conclusion: CTCs may be an independent predictor of OS in CRPC treated with docetaxel chemotherapy. The EGFR expression detected in CTCs was important for assessing the response to chemotherapy and predicting disease outcome.

Centrifugal Filter Device for Detection of Rare Cells With Immuno-Binding

Many investigations have shown circulating tumor cells (CTCs) to serve as a significant biomarker of cancer progression and for cancer treatment. Multiple blood samples detection of CTCs during a course of treatment might facilitate a choice by a medical doctor of an effective drug and a treatment for particular patients. A simple and cost-effective method to identify the trend of decreasing CTCs during a treatment with various therapies is in great demand. A novel multilayer, concentric filter device combined with an immune-binding method enables the enrichment and detection of rare cells in a mass cell population with a separation based on size. Such separation implemented with a filter is among the most efficient, simple and inexpensive methods to isolate cells, but its main disadvantages are clogging, deformation of cells, and a requirement of a significant difference of size between targeted rare cells and normal cells. We designed a concentric filter device and an immune-binding method to create a significant size difference of target cells, and increased the efficiency of separation to identify rare cells with a simple miniature centrifuge in the laboratory. The enrichment of target rare cells from a mass cell population and the detection were demonstrated on mixing targeted MCF-7 blast cancer cells and Jurkat blood cells in ratio 1:1 000 000. The device is prospectively applicable for the detection of circulating tumor cells in a clinical application.

Categorical versus continuous circulating tumor cell enumeration as early surrogate marker for therapy response and prognosis during docetaxel therapy in metastatic prostate cancer patients

Background

Circulating tumor cell (CTCs) counts might serve as early surrogate marker for treatment efficacy in metastatic castration-resistant prostate cancer (mCRPC) patients. We prospectively assessed categorical and continuous CTC-counts for their utility in early prediction of radiographic response, progression-free (PFS) and overall survival (OS) in mCRPC patients treated with docetaxel.

Methods

CTC-counts were assessed in 122 serial samples, as continuous or categorical (<5 vs. ≥5 CTCs) variables, at baseline (q0) and after 1 (q1), 4 (q4) and 10 (q10) cycles of docetaxel (3-weekly, 75 mg/m2) in 33 mCRPC patients. Treatment response (TR) was defined as non-progressive (non-PD) and progressive disease (PD), by morphologic RECIST or clinical criteria at q4 and q10. Binary logistic and Cox proportional hazards regression analyses were used as statistical methods.

Results

Categorical CTC-count status predicted PD at q4 already after one cycle (q1) and after 4 cycles (q4) of chemotherapy with an odds ratio (OR) of 14.9 (p = 0.02) and 18.0 (p = 0.01). Continuous CTC-values predicted PD only at q4 (OR 1.04, p = 0.048). Regarding PFS, categorical CTC-counts at q1 were independent prognostic markers with a hazard ratio (HR) of 3.85 (95 % CI 1.1-13.8, p = 0.04) whereas early continuous CTC-values at q1 failed significance (HR 1.02, 95 % CI 0.99-1.05, p = 0.14). For OS early categorical and continuous CTC-counts were independent prognostic markers at q1 with a HR of 3.0 (95 % CI 1.6-15.7, p = 0.007) and 1.02 (95 % CI 1.0-1.040, p = 0.04).

Conclusions

Categorical CTC-count status is an early independent predictor for TR, PFS and OS only 3 weeks following treatment initiation with docetaxel whereas continuous CTC-counts were an inconsistent surrogate marker in mCRPC patients. For clinical practice, categorical CTC-counts may provide complementary information towards individualized treatment strategies with early prediction of treatment efficacy and optimized sequential treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1478-4) contains supplementary material, which is available to authorized users.

Circulating tumor cells versus objective response assessment predicting survival in metastatic castration-resistant prostate cancer patients treated with docetaxel chemotherapy

PURPOSE

Circulating tumor cell (CTC) counts might display a superior prognostic value for overall survival (OS) compared to objective response criteria (OR) in metastatic castration-resistant prostate cancer (mCRPC) patients.

METHODS

CTCs were detected using the CellSearch™ System out of 122 samples during docetaxel chemotherapy (75 mg/m(2)) at baseline (q0) and after 1 (q1), 4 (q4) and 10 (q10) cycles, in mCRPC patients (n = 33). OR was evaluated by morphologic RECIST and clinical criteria after 4 (q4) and 10 (q10) cycles.

RESULTS

For OS, analyses revealed a significant prognostic value for categorical (<5 vs. ≥5) CTC counts (q0, p = 0.005; q1, p = 0.001; q4, p < 0.001; q10, p = 0.002), RECIST (q4, p < 0.001; q10, p = 0.02) and clinical criteria (q4, p < 0.001; q10, p = 0.02). Concordance of CTC counts with OR revealed a sensitivity of 83.3-87.5 % and a specificity of 68.0-76.5 % with complementary discriminatory power for OS. Comparing CTC counts with concomitant OR at q4 in multivariate analyses, an independent prognostic value for OS was found for CTC counts (HR 3.3; p = 0.02) similar to clinical (HR 4.9; p = 0.02) and radiologic response (HR 3.4; p = 0.051). Comparing the predictive value for death, early post-treatment CTC counts at q1 demonstrated significant accuracy with an area under the curve of 79.5 % (p = 0.004) similar to CTC counts at q4 (76.7 %; p = 0.009). Radiologic and clinical response at q4 displayed accuracy similar to early CTC counts at q1 (72.2 %; p = 0.03 and 75.0 %; p = 0.02) despite low sensitivities.

CONCLUSIONS

CTC counts appear to be an earlier and more sensitive predictor for survival and treatment response than current OR approaches and may provide complementary information toward individualized treatment strategies.

Prognostic role of circulating tumor cells and disseminated tumor cells in patients with prostate cancer: a systematic review and meta-analysis

Circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) displayed their roles in prognosis prediction in prostate cancer. The objective of the present study was to conduct a systematic review and meta-analysis of published literature while investigating the correlation between survival outcome and CTCs or DTCs counts in patients with prostate cancer. Relevant literature was searched in Pubmed and Embase. Survival data of included study were extracted. Forrest plots were used to estimate the effect of CTCs/DTCs on the survival of patients. Publication bias was evaluated using Begg's test. The estimated HRs and 95 % confidence interval for the effect of CTCs/DTCs on overall survival (OS) and biochemical relapse-free survival (bRFS) or disease-free survival (DFS) were 2.43 [2.07, 2.86] (p<0.00001) and 2.15 [1.69, 2.73] (p<0.00001), respectively. Subgroup analysis revealed that CTCs were also relevant to poor prognosis (hazard ratio (HR) 2.43 [2.05, 2.89] for OS, HR 2.46 [2.08, 2.90] for bRFS/DFS). A similar result was yielded in DTCs (1.47 [1.21, 1.80] for DFS). CTCs/DTCs could also predict poor OS in metastatic prostate cancer (2.37 [1.99, 2.82], p<0.00001) and in localized stage (HR 1.84 [1.47, 2.28], p<0.00001). In addition, CTCs/DTCs detected by different methods, especially by CellSearch system (HR for OS 2.36 [1.95, 2.85] and HR for bRFS/DFS 2.53 [1.66, 3.85]), were relevant to poor prognosis. Available evidence supported the notion of the strong prognostic value of CTCs. CTCs are promising biomarkers that are clinically implemented in the therapeutic decision-making process in patients with prostate cancer.

Rapid translation of circulating tumor cell biomarkers into clinical practice: technology development, clinical needs and regulatory requirements

The great hope in circulating tumor cell (CTC) research lies in the use of these rare cells as an accessible "fluid biopsy" that would permit frequent, minimally invasive sampling of tumor cells for similar molecular assays that are performed on traditional biopsies. Given the rarity of CTCs in peripheral circulation, microscale methods show great promise and superiority to capture and analyze these cells from patients with solid tumors. Novel technologies that produce validated CTC biomarkers may finally provide medical oncologists the tools needed to provide precise, personalized medical care for patients with advanced cancer. However, few CTC technologies demonstrate both experimental and clinical evidence of an accurate, reliable and reproducible assay that also meets the regulatory requirements to enter routine clinical practice. Many opportunities exist to incorporate clinical needs and regulatory benchmarks into technology development to more quickly garner FDA approval to direct decisions on patient care. This review will address: 1) device development tailored to address predictive, prognostic and/or therapeutic needs across the multitude of malignancies and disease stages; 2) validation benchmarks for clinical assay development; 3) early establishment of standard operating procedures for sample acquisition and analysis; 4) demonstration of clinical utility; 5) clinical qualification of a novel biomarker; and 6) integration of a newly validated and qualified technology into routine clinical practice. Early understanding and incorporation of these regulatory requirements into assay development can simplify and speed the integration of these novel technologies into patient care. Meeting these benchmarks will lead to the true personalization of cancer therapies, directing initial and subsequent treatments for each individual based on initial tumor characteristics while monitoring for emerging mechanisms of resistance in these continually evolving tumors.

Enrichment, detection and clinical significance of circulating tumor cells

Circulating Tumor Cells (CTCs) are shed from primary or secondary tumors into blood circulation. Accessing and analyzing these cells provides a non-invasive alternative to tissue biopsy. CTCs are estimated to be as few as 1 cell among a few million WBCs and few billion RBCs in 1 ml of patient blood and are rarely found in healthy individuals. CTCs are FDA approved for prognosis of the major cancers, namely, Breast, Colon and Prostate. Currently, more than 400 clinical trials are ongoing to establish their clinical significance beyond prognosis, such as, therapy selection and companion diagnostics. Understanding the clinical relevance of CTCs typically involves isolation, detection and molecular characterization of cells, ideally at single cell level. The need for highly reliable, standardized and robust methodologies for isolating and analyzing CTCs has been widely expressed by clinical thought leaders. In the last decade, numerous academic and commercial technology platforms for isolation and analysis of CTCs have been reported. A recent market report highlighted the presence of more than 100 companies offering products and services related to CTCs. This review aims to capture the state of the art and examines the technical merits and limitations of contemporary technologies for clinical use.

Microsieve lab-chip device for rapid enumeration and fluorescence in situ hybridization of circulating tumor cells

Herein we present a lab-chip device for highly efficient and rapid detection of circulating tumor cells (CTCs) from whole blood samples. The device utilizes a microfabricated silicon microsieve with a densely packed pore array (10(5) pores per device) to rapidly separate tumor cells from whole blood, utilizing the size and deformability differences between the CTCs and normal blood cells. The whole process, including tumor cell capture, antibody staining, removal of unwanted contaminants and immunofluorescence imaging, was performed directly on the microsieve within an integrated microfluidic unit, interconnected to a peristaltic pump for fluid regulation and a fluorescence microscope for cell counting. The latter was equipped with a dedicated digital image processing program which was developed to automatically categorize the captured cells based on the immunofluorescence images. A high recovery rate of >80% was achieved with defined numbers of MCF-7 and HepG2 cancer cells spiked into human whole blood and filtered at a rapid flow rate of 1 mL min(-1). The device was further validated with blood drawn from various cancer patients (8 samples). The whole process, from sample input to result, was completed in 1.5 h. In addition, we have also successfully demonstrated on-microsieve fluorescence in situ hybridization for single cell molecular analysis. This simple method has great potential to supplant existing complex CTC detection schemes for cancer metastasis analysis.

Development of the "Three-step MACS": a novel strategy for isolating rare cell populations in the absence of known cell surface markers from complex animal tissue

To circumvent the difficulty of isolating specific cell populations by MACS from dissociated complex animal tissue, when their proportions reached levels similar to that of the background, we developed the "Three-step MACS" strategy. Cells of interest are defined by their expression of a particular gene(s) of interest rather by than their natural cell surface markers or size. A two-component transgenic cell surface protein, for two sequential rounds of MACS, is expressed under the promoter control of the endogenous gene of interest by means of gene targeting and the generation of transgenic tissue. An initial step to remove dead cells is also used. Here, we describe proof-of-concept experiments, using the biotin acceptor peptide (BAP)-low-affinity nerve growth factor receptor as the two-component protein. The first component, the BAP, can be biotinylated in specific subsets of cells expressing a particular gene by expressing the biotinylating enzyme, hBirA = humanized BirA (hBirA), under the promoter control of another gene defining the specific subpopulation. We showed that a rare population of cells (1.1% of the 13.5 days postcoital mouse embryo) could be enriched to a sufficiently high purity (84.4%). From another sample with 0.1% of our cells of interest, we achieved a 40.3% pure sample. The low cost, speed, and technical ease of the Three-step MACS also make it scalable and hence, an ideal method for preparing sufficient quantities of biological samples for sensitive, high-throughput assays.

Quantitative RT-PCR analysis of PSA and prostate-specific membrane antigen mRNA to detect circulating tumor cells improves recurrence-free survival nomogram prediction after radical prostatectomy

BACKGROUND

Circulating tumor cell (CTC) analysis is a potential new biomarker in prostate cancer. We hypothesize that quantitative detection of CTCs in patients pre- and post-radical prostatectomy (RP) using quantitative TaqMan® fluorogenic RT-PCR will improve the accuracy of the Kattan nomogram to predict the probability of recurrence-free survival (RFS) post-RP.

METHODS

Ninty-two patients who underwent RP between 2004 and 2009 had venous blood samples taken pre- (Day - 1) and post-operatively (Day + 7). We performed quantitative Taqman® RT-PCR to detect circulating prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) mRNA. We calculated both the logarithmic ratio of Day + 7/Day - 1 for PSA (PSAr) and PSMA (PSMAr) expression (log(Day+7/Day-1) ) and the Kattan nomogram predicted probability of disease recurrence for each patient. We then analyzed how the AUC-ROC analysis for the Kattan nomogram prediction alone (K) compared to the addition of the PSAr and PSMAr in predicting 5-year RFS.

RESULTS

The mean age (years), PSA (ng/ml), and follow-up (mo) was 65.1, 9.13, and 72, respectively. The AUCs for K, PSAr + K, and PSMAr + K were 0.752 (95%CI 0.620-0.860), 0.830 (95%CI 0.740-0.911), and 0.837 (95%CI 0.613-0.923), respectively (P = 0.03). The Kattan 5-year PSA RFS was 75%. The actual 5-year PSA RFS survival rate was 77%.

CONCLUSIONS

Data from modern quantitative RT-PCR to detect circulating prostate-derived PSA and PSM mRNA pre- and post-RP improves the accuracy of the Kattan nomogram to predict biochemical recurrence.

Circulating tumor cells as a predictive biomarker in patients with hormone-sensitive prostate cancer

Little information exists regarding the utility circulating tumor cell (CTC) enumeration in hormone sensitive prostate cancer. We enumerated CTC in 33 consecutive patients undergoing androgren deprivation therapy (ADT) at our institution. Multivariate analysis revealed baseline CTC as the only independent predictor of progression to CRPC. These data suggest that baseline CTC may identify those unlikely to benefit from ADT.

INTRODUCTION

Circulating tumor cell (CTC) enumeration by using the Cellsearch platform has established prognostic and predictive value in patients with metastatic castration-resistant prostate cancer (mCRPC). Limited information exists regarding the clinical utility of CTC enumeration in metastatic hormone-sensitive prostate cancer (mHSPC). The goal of this study was to prospectively determine the relative clinical utility of CTCs in mHSPC.

PATIENTS AND METHODS

We analyzed serial CTC in conjunction with other classic biomarkers in 33 consecutive patients treated at the Nevada Cancer Institute with HSPC initiating androgen deprivation therapy and correlated these patients with prognostic prostate-specific antigen (PSA) endpoints and onset of CRPC.

RESULTS

Initial CTC correlated positively with lactate dehydrogenase and alkaline phosphatase, and were unrelated to PSA and testosterone. In univariate analysis, baseline CTC, alkaline phosphatase, lactate dehydrogenase, testosterone, and follow-up CTC were individual predictors of progression to CRPC. In a multivariate Cox regression, only baseline CTC retained independent predictive value. Threshold analysis revealed the cutpoint that optimized specificity and sensitivity of the test to be 3 cells per 7.5 mL whole blood. Baseline CTC also correlated well with PSA nadir benchmarks.

CONCLUSIONS

Initial CTC values predict the duration and magnitude of response to hormonal therapy. CTC enumeration may identify patients at risk of progression to CRPC before initiation of androgen deprivation therapy.

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.

An update on the changing indications for androgen deprivation therapy for prostate cancer

Quality of life has become increasingly more important for men diagnosed with prostate cancer. In light of this and the recognized risks of androgen deprivation therapy (ADT), the guidelines and use of ADT have changed significantly over the last few years. This paper reviews the current recommendations and the future perspectives regarding ADT. The benefits of ADT are evident neoadjuvantly and adjuvantly in patients treated with external beam radiation therapy for intermediate- and high-risk disease, in patients who have undergone prostatectomy with lymph node involvement, in high-risk patients after definitive therapy, and in patients who have developed progression or metastasis. Finally, this paper reviews the risks and benefits of each of these scenarios and the risks of androgen deprivation in general, and it delineates the areas where ADT was previously recommended, but where evidence is lacking for its additional benefit.

Methods of detection of circulating melanoma cells: a comparative overview

Disease dissemination is the major cause of melanoma-related death. A crucial step in the metastatic process is the intravascular invasion and circulation of melanoma cells in the bloodstream with subsequent development of distant micrometastases that is initially clinically undetectable and will eventually progress into clinically apparent metastasis. Therefore, the use of molecular methods to detect circulating melanoma cells may be of value in risk stratification and clinical management of such patients. Herein, we review the currently applied techniques for the detection, isolation, enrichment and further characterization of circulating melanoma cells from peripheral blood samples in melanoma patients. Furthermore, we provide a brief overview of the various molecular markers currently being evaluated as prognostic indicators of melanoma progression.

Infiltration of tumour-associated macrophages in prostate biopsy specimens is predictive of disease progression after hormonal therapy for prostate cancer

OBJECTIVE

• To evaluate tumour-associated macrophage (TAM) infiltration in prostate biopsy specimens as a possible prognostic factor for prostate cancer (PCa) after hormonal therapy.

PATIENTS AND METHODS

• Immunostaining of TAMs in prostate biopsy specimens was performed using a monoclonal antibody CD68 for 71 patients having PCa treated with hormonal therapy. • Six microscopic (×400) fields around the cancer foci were selected for TAM counting.

RESULTS

• The median value of serum prostate-specific antigen (PSA) was 50.1 ng/mL, and the median TAM count was 22. • Recurrence-free survival was significantly better in patients with fewer TAMs (<22) than in those with higher numbers of TAMs (≥22) (P < 0.001). • TAM count was higher in those with higher serum PSA (PSA), higher Gleason score, clinical T stage or those with PSA failure. Cox multivariate analysis showed that TAM count is one of the prognostic factors for PCa treated by hormonal therapy (P < 0.0001).

CONCLUSION

• TAM infiltration in prostate needle biopsy specimens is a useful predictive factor for PSA failure or progression of PCa after hormonal therapy.

Association of circulating tumor cells with tumor-related methylated DNA in patients with hormone-refractory prostate cancer

OBJECTIVES

To assess whether circulating tumor cells with tumor-related methylated DNA can be used to predict survival in patients with hormone-refractory prostate cancer.

METHODS

Blood samples from 76 patients with hormone-refractory prostate cancer were analyzed. Circulating tumor cells were enumerated with the CellSearch System in whole blood. This system was developed using an epithelial cell adhesion molecule antibody-based immunomagnetic capture and automated staining methodology. Hypermethylation at adenomatosis polyposis coli, glutathione-S-transferase-pi, prostaglandin-endoperoxide synthase 2, multidrug resistance 1 and Ras association domain family 1 isoform A was analyzed using a sensitive SYBR green methylation-specific polymerase chain reaction. Patient charts were retrospectively examined.

RESULTS

Median overall survival time was 19.3 months (range 11-48). Of the 76 patients, 47 (62%) had five or more circulating tumor cells, with a median overall survival of 12.0 months compared with 26.0 months for patients with fewer than five circulating tumor cells (P < 0.001). Circulating tumor cells were detected in 36 of 39 (92%) patients with tumor-related methylated DNA but only 11 of 37 (30%) patients without methylated DNA (P < 0.001). Thirty-nine (51%) patients had one or more methylated marker. Their median overall survival time was 12.0 months compared with 48.0 months or more for patients without methylated DNA (P < 0.001). Prostate-specific antigen-doubling time, circulating tumor cells and methylated DNA were independent predictors of overall survival time.

CONCLUSIONS

Hormone refractory prostate cancer patients with circulating tumor cells and/or tumor-related methylated DNA show a significantly poorer outcome than those without these blood markers.

Immunomagnetic quantification of circulating tumor cells in patients with urothelial cancer

OBJECTIVES

To evaluate the relationship between circulating tumor cells (CTC) and clinical parameters in metastatic urothelial cancer (UC).

METHODS

CTC were enumerated with the CellSearch System, which was developed using an EpCAM antibody-based immunomagnetic capture and automated staining methodology. UC cell lines (RT4, T24, TCC, UMUC3 and 253J) and mixed blood from healthy males were analyzed. Blood samples from 16 patients without metastatic UC and 20 patients with metastatic UC were also analyzed.

RESULTS

The accuracy and reliability of the assay were determined using spiked UC cells (RT4 and T24), which showed a strong linear correlation (r = 0.99) and recovery rate of 94% +/- 5% and 84% +/- 6%, respectively. Three UC cell lines (TCC, UMUC3 and 253J) tested negative. The 16 patients without metastatic UC tested negative as well. Eleven (55%) patients with metastatic UC tested positive for at least one CTC. Seven (35%) had two or more CTC. Significantly more CTC were seen in patients with two or more sites of metastasis than those with one site of metastasis (P = 0.004).

CONCLUSIONS

Based on these findings, CTC could represent a potential marker to monitor the response to chemotherapy in patients with metastatic UC.

Update on the management of prostate cancer with goserelin acetate: patient perspectives

The guidelines for the use of androgen deprivation therapy (ADT) have changed significantly over the last 5 years. This paper reviews the current recommendations and documents the reasons for these changes, in a review of the world's literature on ADT over the last 5 years. Special emphasis on randomized controlled trials and high-impact journals was included in the Medline search and review. One hundred articles on this topic written in the last 5 years were reviewed. Fifty-nine contained nonindustry-biased findings in major-impact journals and were available in English. The benefits of ADT are evident in several areas, including neoadjuvantly and adjuvantly in patients treated with external beam radiation therapy for intermediate- and high-risk disease; in patients who have undergone prostatectomy and who are found to have lymph node involvement on surgical resection; in high-risk patients after definitive therapy; and in patients who have developed symptomatic local progression or metastasis. This paper reviews the risks and benefits in each of these scenarios and the risks of androgen deprivation in general, and delineates the areas where ADT was previously recommended, but has been found to no longer be of benefit.

Prognostic value of prostate circulating cells detection in prostate cancer patients: a prospective study

In clinically organ-confined prostate cancer patients, bloodstream tumour cell dissemination generally occurs, and may be enhanced by surgical prostate manipulation. To evaluate cancer-cell seeding impact upon patient recurrence-free survival, 155 patients were prospectively enrolled then followed. Here, 57 patients presented blood prostate cell shedding preoperatively and intraoperatively (group I). Of the 98 preoperatively negative patients, 53 (54%) remained negative (group II) and 45 (46%) became intraoperatively positive (group III). Median biological and clinical recurrence-free time was far shorter in group I (36.2 months, P<0.0001) than in group II (69.6 months) but did not significantly differ in group II and III (69.6 months vs 65.0). Such 5-year follow-up data show that preoperative circulating prostate cells are an independent prognosis factor of recurrence. Moreover, tumour handling induces cancer-cell seeding but surgical blood dissemination does not accelerate cancer evolution.

Prognostic significance of circulating tumor cells in patients with hormone refractory prostate cancer

PURPOSE

Using the CellSearch System we evaluated whether circulating tumor cells predict survival in patients with hormone refractory prostate cancer.

MATERIALS AND METHODS

Circulating tumor cells were counted with the CellSearch System in whole blood. This system was developed using epithelial cell adhesion prostate cancer antibody based, immunomagnetic capture and automated staining methodology. Blood samples from 64 patients with hormone refractory prostate cancer were analyzed.

RESULTS

A threshold of 5 or more circulating tumor cells per 7.5 ml blood was used to evaluate the ability of circulating tumor cells to predict survival. Patient charts were retrospectively examined to determine median overall survival, which was 4 to 27 months (mean +/- SD 14.3 +/- 4.2, median 12.1). Of the 64 patients 32 (50%) had 5 or more circulating tumor cells with a median overall survival of 13.0 months compared with 20.0 months in patients with fewer than 5 (p <0.001). Circulating tumor cells and prostate specific antigen doubling time were significant parameters predicting overall survival on univariate and multivariate analyses. Overall survival in cases that converted from increased to nonincreased circulating tumor cell levels was longer than in cases that converted from nonincreased to increased levels after initiating the circulating tumor cell assay (p = 0.026).

CONCLUSIONS

In this study 5 or more circulating tumor cells in 7.5 ml blood was associated with survival in patients with hormone refractory prostate cancer. Circulating tumor cells may be an independent predictor of overall survival in patients with hormone refractory prostate cancer but they may also complement prostate specific antigen.