Review: Biological relevance of disseminated tumor cells in cancer patients

Circulating tumor cells measurements in hepatocellular carcinoma

Liver cancer is the fifth most common cancer in men and the seventh in women. During the past 20 years, the incidence of HCC has tripled while the 5-year survival rate has remained below 12%. The presence of circulating tumor cells (CTC) reflects the aggressiveness nature of a tumor. Many attempts have been made to develop assays that reliably detect and enumerate the CTC during the development of the HCC. In this case, the challenges are (1) there are few markers specific to the HCC (tumor cells versus nontumor cells) and (2) they can be used to quantify the number of CTC in the bloodstream. Another technical challenge consists of finding few CTC mixed with million leukocytes and billion erythrocytes. CTC detection and identification can be used to estimate prognosis and may serve as an early marker to assess antitumor activity of treatment. CTC can also be used to predict progression-free survival and overall survival. CTC are an interesting source of biological information in order to understand dissemination, drug resistance, and treatment-induced cell death. Our aim is to review and analyze the different new methods existing to detect, enumerate, and characterize the CTC in the peripheral circulation of patients with HCC.

Application of conditional probability analysis to distant metastases from lung cancer

The aim of this study was to reveal whether there was non-randomness in the occurrence of metastasis and, if the non-randomness was denied, whether there were specific metastatic patterns in lung cancer patients. Patients who presented with pathologically diagnosed lung cancer between January 1986 and March 2009 at our hospitals were included. A statistical method and conditional probability analysis were used to analyze the data. Under the condition of one metastatic organ A (lung, bone, brain, liver or adrenal gland; the 5 most common metastatic organs), we determined the conditional probability of distant metastasis to a specific organ B, which was written as P(B | A), and compared it with the probability of distant metastasis P(B). The study group consisted of 1,994 patients. Of the 1,994 patients, 839 (42.1%) had distant metastases at the time of the initial diagnosis of lung cancer. With the exception of the comparisons between P(lung) and P(lung | adrenal gland) and between P(adrenal gland) and P(adrenal gland | lung), there were statistically significant differences between P(B | A) and P(B) in the 5 metastatic organs. In addition, P(B | A) and P(C | B | A) varied according to each organ and P(confined to A), P(confined to A and B) and P(confined to A, B and C) were different in each metastatic organ. In lung cancer patients, distant metastasis occurred non-randomly and there may be certain specific patterns of distant metastasis. The accumulation of knowledge of specific patterns of metastasis may aid the approach to individualized treatments.

Organ-specific markers in circulating tumor cell screening: an early indicator of metastasis-capable malignancy

Circulating tumor cells (CTCs) represent an important biological link in the spread of primary solid tumors to the metastatic disease responsible for most cancer mortality. Their detection in the peripheral blood of patients with many different carcinomas has shown that tumor-cell dissemination can proceed at an early stage of tumor development and their presence is associated with poor clinical outcomes, particularly in metastatic disease. In this article we describe how the increasingly sensitive isolation and detailed molecular characterization of CTCs has greatly improved our understanding of metastatic proliferation. We focus on how CTC detection and knowledge of the molecular architecture of these cells can serve as biomarkers to signal metastasis-capable disseminating cells and predict therapy-specific response. This has marked clinical utility for improved selection of systemic therapies to the individual needs of a cancer patient, real-time monitoring of metastatic disease treatments and the development of new targeted therapies.

Cell-permeable NM23 blocks the maintenance and progression of established pulmonary metastasis

Occult metastases are a major cause of cancer mortality, even among patients undergoing curative resection. Therefore, practical strategies to target the growth and persistence of already established metastases would provide an important advance in cancer treatment. Here, we assessed the potential of protein therapy using a cell permeable NM23-H1 metastasis suppressor protein. Hydrophobic transduction domains developed from a screen of 1,500 signaling peptide sequences enhanced the uptake of the NM23 protein by cultured cells and systemic delivery to animal tissues. The cell-permeable (CP)-NM23 inhibited metastasis-associated phenotypes in tumor cell lines, blocked the establishment of lung metastases, and cleared already established pulmonary metastases, significantly prolonging the survival of tumor-bearing animals. Therefore, these results establish the potential use of cell-permeable metastasis suppressors as adjuvant therapy against disseminated cancers.

Update on HER2 testing for breast and upper gastrointestinal tract cancers

With the regulatory approvals in Europe and the USA of trastuzumab-based anti-HER2 targeted therapy for upper gastrointestinal cancers in 2010, HER2 testing has now become universal for newly diagnosed cases of both breast cancer and adenocarcinomas of esophagus, stomach and gastroesophageal origin. In the 12 years or more since the approval of trastuzumab for breast cancer, general refinements in approaches to HER2 testing, including a greater understanding of the implications of preanalytic factors impacting the test results and the application of standardization of reporting of HER2 test results, have taken place. There has also been continuing development in breast cancer with the introduction of new HER2 tests, including non-FISH tests, dimerization assays, phosphorylated HER2 receptor tests, mRNA-based tests, HER2 gene sequencing tests and the application of HER2 testing to circulating tumor cells. Most recently, the introduction of HER2 testing for upper gastrointentinal malignancies has emphasized the need for performing and interpreting slide-based assays in a manner unique to these specimens and not to apply the breast cancer testing protocols to esophageal and gastric adenocarcinomas.

Role of Src in breast cancer cell migration and invasion in a breast cell/bone-derived cell microenvironment

The preferential metastasis of breast cancer cells to bone comprises a complex set of events including homing and preferential growth, which may require unique factors produced by bone or other cells in the immediate microenvironment. In this study, an in vitro co-culture system composed of bone mesenchymal stem cells and breast cancer cell lines is used to examine the role of Src kinase on breast cancer cell migration and invasion in the presence of bone-derived cells. This research shows that Src kinase activity in breast cancer cell lines with either high or low levels of endogenous Src activity is increased by bone-derived cell-conditioned medium but not HS68 fibroblast-conditioned medium. Breast cancer cells exhibit enhanced migration in co-culture with bone-derived cells but not HS68 fibroblasts or no co-cultured cells. Inhibition of Src kinase activity using the inhibitors PP2 or saracatinib or using siRNA abrogates the preferential migration of the breast cancer cell lines in response to bone-derived cells. Inhibition of Src activity with saracatinib does not have any significant effect on breast cancer cell invasion in the presence of bone-derived cells. Factors are identified that are produced preferentially by bone-derived cells over HS68 cells that may impact breast cancer cell behavior. This research implicates Src kinase as an important effector of bone-derived cell signals on breast cancer cell migration.

Mechanism of the mesenchymal-epithelial transition and its relationship with metastatic tumor formation

Cancer metastasis consists of a sequential series of events, and the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are recognized as critical events for metastasis of carcinomas. A current area of focus is the histopathological similarity between primary and metastatic tumors, and MET at sites of metastases has been postulated to be part of the process of metastatic tumor formation. Here, we summarize accumulating evidence from experimental studies that directly supports the role of MET in cancer metastasis, and we analyze the main mechanisms that regulate MET or reverse EMT in carcinomas. Given the critical role of MET in metastatic tumor formation, the potential to effectively target the MET process at sites of metastasis offers new hope for inhibiting metastatic tumor formation.

Pharmacogenomics and cancer stem cells: a changing landscape?

Pharmacogenomics in oncology holds the promise to personalize cancer therapy. However, its clinical application is still limited to a few genes, and, in the large majority of cancers, the correlation between genotype and clinical outcome has been disappointing. One possible explanation is that current pharmacogenomic studies do not take into account the emerging role of cancer stem cells (CSCs) in drug sensitivity and resistance. CSCs are a subpopulation of cells driven by specific signal-transduction pathways, but genetic variants affecting their activity are generally neglected in current pharmacogenomic studies. Moreover, in several malignancies, CSCs represent a rare sub-population; therefore, whole tumor profiling might mask CSC gene expression patterns. This article reviews current evidence on CSC chemoresistance and shows how common genetic variations in CSC-related genes may predict individual response to anti-cancer agents. Furthermore, we provide insights into the design of pharmacogenomic studies to address the clinical usefulness of CSC genetic profiling.

Circulating tumour cells in peripheral blood: potential impact on breast cancer outcome

INTRODUCTION

In breast cancer, the metastatic process may involve the dissemination of circulating tumour cells (CTCs) through the blood and lymphatic system prior to the colonisation of distant organs. Here we demonstrate the predictive capacity of CTCs for detecting risk of death in breast cancer patients during established time intervals.

METHODS

CTCs were identified by immunocytochemical methods following isolation by selective immunomagnetic cell separation of cytokeratin-positive cells. Serial blood samples from 65 patients were collected at roughly monthly intervals for up to 50 months. Follow-up was conducted at different intervals: 1-5, >5-12, >12-24 and >24-50 months.

RESULTS

Both presence and number of CTCs were correlated to risk of death: patients with CTCs at any time during follow-up had a higher risk of death (p=0.035) than patients without CTCs. Furthermore, during the first 5 months of therapy, patients with >5 CTCs had a higher risk of death than patients with <5 CTCs (p=0.002).

CONCLUSIONS

Our results show that the persistence of CTCs after chemotherapy, particularly during the first 5 months, could define a group of patients with a high risk of relapse.

The interrelating dynamics of hypoxic tumor microenvironments and cancer cell phenotypes in cancer metastasis

The interrelating dynamics of the primary tumor cells and their surrounding microenvironment might determine phenotypic characteristics of disseminated tumor cells and contribute to cancer metastasis. Cytoprotective mechanisms (e.g., energy metabolism control, DNA damage response, global translation control and unfolded protein response) exert selective pressure in the tumor microenvironment. In particular, adaptation to hypoxia is vital for survival of malignant cells in the tumor and at distant sites such as the bone marrow. In addition to the stress response, the ability of tumor cells to undergo certain cellular re-differentiation programmes like the epithelial-mesenchymal transition (EMT), which is linked to cancer stemness, appears to be important for successful cancer cell spread. Here we will discuss the selection pressures that eventually lead to the formation of overt metastases. We will focus the properties of the microenvironment including (i) metabolic and cytoprotective programs that ensure survival of disseminated tumor cells, (ii) blood vessel structure, and (iii) the hypoxia-normoxia switch as well as intrinsic factors affecting the evolvement of novel tumor cell populations.

Prognostic relevance of circulating tumor cells in metastatic uveal melanoma

OBJECTIVE

Uveal melanoma primarily metastasizes hematogenously with metastases often confined to the liver. The aim of this study was to investigate the presence of circulating tumor cells (CTC) in patients with metastatic disease as a marker for systemic disease and to determine their prognostic relevance.

METHODS

Blood samples from 68 patients were collected at the time of initial treatment of metastases. mRNA expression of tyrosinase and MelanA/MART1 as a surrogate marker for the presence of CTC was analyzed by real-time RT-PCR and compared with patient characteristics.

RESULTS

CTC were detected in 63% of all patients and in 67% of the 48 patients with only liver metastases. Univariate and multivariate analyses revealed PCR results and serum lactate dehydrogenase as independent prognostic factors for progression-free (hazard ratios 2.2/3.5) and overall survival (hazard ratios 4.0/6.5). Combination of PCR and lactate dehydrogenase divided the patient cohort into 3 groups with distinct prognosis.

CONCLUSION

CTC as evidence for systemic disease can be found in the majority of patients with metastatic uveal melanoma, including patients with visible disease confined to the liver. Detection of CTC-specific mRNA transcripts for tyrosinase and MelanA/MART1 by PCR is a poor prognostic factor for progression-free and overall survival. Characterization of CTC could improve the understanding of their biology.

Circulating tumor cells as a window on metastasis biology in lung cancer

Circulating tumor cell (CTC) number in metastatic cancer patients yields prognostic information consistent with enhanced cell migration and invasion via loss of adhesion, a feature of epithelial-to-mesenchymal transition (EMT). Tumor cells also invade via collective migration with maintained cell-cell contacts and consistent with this is the circulating tumor microemboli (CTM; contiguous groups of tumor cells) that are observed in metastatic cancer patients. Using a blood filtration approach, we examined markers of EMT (cytokeratins, E-cadherin, vimentin, neural cadherin) and prevalence of apoptosis in CTCs and CTM to explore likely mechanism(s) of invasion in lung cancer patients and address the hypothesis that cells within CTM have a survival advantage. Intra-patient and inter-patient heterogeneity was observed for EMT markers in CTCs and CTM. Vimentin was only expressed in some CTCs, but in the majority of cells within CTM; E-cadherin expression was lost, cytoplasmic or nuclear, and rarely expressed at the surface of the cells within CTM. A subpopulation of CTCs was apoptotic, but apoptosis was absent within CTM. This pilot study suggests that EMT is not prosecuted homogeneously in tumor cells within the circulation of lung cancer patients and that collective migration and enhanced survival of cells within CTM might contribute to lung cancer metastasis. Multiplex analysis and further detailed exploration of metastatic potential and EMT in CTCs/CTM is now warranted in a larger patient cohort.

Lung-residing metastatic and dormant neuroblastoma cells

The mechanism by which dormant tumor cells can begin growing after long periods of inactivity and accelerate disease recurrence is poorly understood. The present study characterizes dormant neuroblastoma (NB) cells, as well as metastatic cells, which reside in the same organ microenvironment. A xenograft model of human NB consisting of variants that generate nonmetastatic local tumors in the orthotopic inoculation site and variants that generate lung metastatic NB (MetNB) cells was developed in our laboratory. The present study shows that lungs of mice inoculated with nonmetastatic NB variants contain disseminated neuroblastoma (DisNB) human cells. Both DisNB and MetNB variants expressed a similar tumorigenicty phenotype in vivo, whereas the MetNB variants produced a heavy metastatic load and the DisNB variants produced no or little metastasis. A comparative in vitro characterization of MetNB and DisNB cells revealed similarities and differences. DisNB, but not MetNB cells, expressed the minimal residual disease markers PHOX2B and TH. MetNB cells demonstrated higher migratory capacity, an elevated matrix metalloproteinase (MMP) secretion, and a higher constitutive phosphorylation of extracellular signal-regulated kinase (ERK) than DisNB cells. We suggest that characteristics common to both MetNB and DisNB cells were acquired relatively early in the metastatic process and the characteristics that differ between these variants were acquired later. We hypothesize that the DisNB cells are metastasis precursors, which may progress toward metastasis under certain microenvironmental conditions.

Multiple biomarker expression on circulating tumor cells in comparison to tumor tissues from primary and metastatic sites in patients with locally advanced/inflammatory, and stage IV breast cancer, using a novel detection technology

Patients with locally advanced/inflammatory breast cancer (LABC/IBC) face a high likelyhood of recurrence and prognosis for relapsed, or de novo stage IV metastatic breast cancer (MBC) remains poor. Estrogen (ER) and HER2 receptor expression on primary or MBC allow targeted therapies, but an estimated 10-18% of tumors do not exhibit these biomarkers and survival in these cases is even poorer. Variations in discordance rates for the expression of ER and HER2 receptors have been observed between primary and metastatic tumors and such discordances may lead to suboptimal treatment. Circulating tumor cells (CTCs) are considered the seeds of residual disease and distant metastases and their characterization could help guide treatment selection. To explore this possibility, we used multiple biomarker assessment of CTCs in comparison to primary and metastatic tumor sites. Thirty-six patients with LABC/IBC, or stage IV MBC were evaluated. Blood samples were procured prior to initiating or changing therapy. CTCs were identified based on presence of cytokeratin and nucleus staining, and the absence of CD45. A multimarker assay was developed to simultaneously quantify expression of HER2, ER, and ERCC1, a DNA excision repair protein. Novel fiber-optic array scanning technology (FAST) was used for sensitive location of CTCs. CTCs were detected in 82% of MBC and 62% LABC/IBC cases. Multiplex marker expression was successfully carried out in samples from18 patients with MBC and in 8 patients with LABC/IBC that contained CTCs. In MBC, we detected actionable discordance rates of 40 and 23%, respectively for ER and HER2 where a biomarker was negative in the primary or metastatic tumor and positive in the CTCs. In LABC/IBC, actionable discordances were 60 and 20% for ER and HER2, respectively. Pilot trials evaluating the effectiveness of treatment selections based on actionable discordances between biomarker expression patterns on CTCs and primary or metastatic tumor sites may allow for a prospective assessment of CTC-based individualized targeted therapies.

Do all roads lead to Rome? Routes to metastasis development

Metastasis, the life-threatening aspect of cancer, is a systemic disease process. Considerable progress has been made in recent years regarding how tumor cells circulating in the blood and lymphatic systems interact with and extravasate into secondary sites, and what determines whether these disseminated tumors cells survive, remain dormant or go on to form macrometastases. New insights into the routes that tumor cells take once leaving the primary tumor have emerged. Novel concepts regarding early seeding of metastases coupled to parallel progression, self-seeding of primary tumors by circulating tumor cells and the induction of premetastatic niches in distant organs by primary tumors have come to the fore. The perceived role of the lymphatic system in determining patterns of metastasis formation in distant organs has been reassessed. Together these new insights have the potential to offer new therapeutic options. In particular, the regulation of tumor cell dormancy emerges as a key event in metastasis formation, and therapeutic control of dormancy holds the promise of rendering cancer a chronic rather than life-threatening disease.

Clinical significance of circulating tumor cells, including cancer stem-like cells, in peripheral blood for recurrence and prognosis in patients with Dukes' stage B and C colorectal cancer

PURPOSE

Using multiple genetic markers, including cancer stem-like cells, we evaluated the clinical significance of circulating tumor cells (CTCs) as a prognostic factor for overall survival (OS) and disease-free survival (DFS) in the peripheral blood (PB) of patients with colorectal cancer (CRC) who had undergone curative surgery.

PATIENTS AND METHODS

In a multi-institutional study, 735 patients with CRC were assigned to a retrospective training set (n = 420) or prospective validation set (n = 315). CTCs that expressed carcinoembryonic antigen (CEA), cytokeratin (CK) 19, CK20, and/or CD133 (CEA/CK/CD133) mRNA in PB were detected using real-time reverse transcription polymerase chain reaction assay.

RESULTS

In the training sets, OS and DFS of patients who were positive for CEA/CK/CD133 were significantly worse than those of patients who were negative for these markers (P < .001). At each staging analysis, OS and DFS of patients with Dukes' stage B or C cancer who were positive for CEA/CK/CD133 were significantly worse than those of patients who were negative for these markers (P < .003 and P < .001 in Dukes' stage B; P < .001 in Dukes' stage C). In contrast, in patients with Dukes' stage A, no significant differences were seen between patients who were positive for these markers and those who were negative. Cox multivariate analysis demonstrated that CEA/CK/CD133 was a significant prognostic factor for OS (hazard ratio [HR], 3.84; 95% CI, 2.41 to 6.22; P < .001) and DFS (HR, 3.02; 95% CI, 1.83 to 5.00; P < .001). In particular, in patients with Dukes' stage B and C cancer, CEA/CK/CD133 demonstrated significant prognostic value. In validation sets, similar results were confirmed in patients with Dukes' stage B and C cancer.

CONCLUSION

In patients with Dukes' stage B and C CRC who require adjuvant chemotherapy, detection of CEA/CK/CD133 mRNA in PB is a useful tool for determining which patients are at high risk for recurrence and poor prognosis.

Gap junction-mediated import of microRNA from bone marrow stromal cells can elicit cell cycle quiescence in breast cancer cells

Bone marrow (BM) metastasis of breast cancer (BC) can recur even decades after initial diagnosis and treatment, implying the long-term survival of disseminated cancer cells in a dormant state. Here we investigated the role of microRNAs (miRNA) transmitted from BM stroma to BC cells via gap junctions and exosomes in tumor cell quiescence. MDA-MB-231 and T47D BC cells arrest in G(0) phase of the cell cycle when cocultured with BM stroma. Analyses of miRNA expression profiles identified numerous miRNAs implicated in cell proliferation including miR-127, -197, -222, and -223 targeting CXCL12. Subsequently, we showed that these CXCL12-specific miRNAs are transported from BM stroma to BC cells via gap junctions, leading to reduced CXCL12 levels and decreased proliferation. Stroma-derived exosomes containing miRNAs also contributed to BC cell quiescence, although to a lesser degree than miRNAs transmitted via gap junctions. This study shows that the transfer of miRNAs from BM stroma to BC cells might play a role in the dormancy of BM metastases.

[Long-term survival of personalized surgical treatment of locally advanced non-small cell lung cancer based on molecular staging]

BACKGROUND AND OBJECTIVE

Approximately 35%-40% of patients with newly diagnosed non-small cell Lung cancer have locally advanced disease. The average survival time of these patients only have 6-8 months with chemotherapy. The aim of this study is to explore and summarize the probability of detection of micrometastasis in peripheral blood for molecular staging, and for selection of indication of surgical treatment, and beneficiary of neoadjuvant chemotherapy and postoperative adjuvant therapy in locally advanced lung cancer; to summarize the long-time survival result of personalized surgical treatment of 516 patients with locally advanced non-small cell lung cancer based on molecular staging methods.

METHODS

CK19 mRNA expression of peripheral blood samples was detected in 516 lung cancer patients by RT-PCR before operation for molecular diagnosis of micrometastasis, personalized molecular staging, and for selection of indication of surgical treatment and the beneficiary of neoadjuvant chemotherapy and postoperative adjuvant therapy in patients with locally advanced nonsmall cell lung cancer invaded heart, great vessels or both. The long-term survival result of personalized surgical treatment was retrospectively analyzed in 516 patients with locally advanced non-small cell lung cancer based on molecular staging methods.

RESULTS

There were 322 patients with squamous cell carcinoma and 194 cases with adenocarcinoma in the series of 516 patients with locally advanced lung cancer involved heart, great vessels or both. There were 112 patients with IIIA disease and 404 cases with IIIB disease according to P-TNM staging. There were 97 patients with M-IIIA disease, 278 cases with M-IIIB disease and 141 cases with III disease according to our personalized molecular staging. Of the 516 patients, bronchoplastic procedures and pulmonary artery reconstruction was carried out in 256 cases; lobectomy combined with resection and reconstruction of partial left atrium was performed in 41 cases; Double sleeve lobectomy combined with resection and reconstruction of super vena cava was carried out in 90 cases; Lobectomy combined with resection and reconstruction of diaphragm was performed in 3 cases; Double sleeve lobectomy combined with resection and reconstruction of partial left atrium was performed in 30 cases; Bronchoplastic procedures and pulmonary artery reconstruction combined with reconstruction of aorta sheath was carried out in 10 cases; Right pneumonectomy combined with resection and reconstruction partial left atrium, total right diaphragm with Dacron, and post cava and right liver vein was performed in one case; Lobectomy combined with resection and reconstruction of carina was carried out in 10 cases; Bronchoplastic procedures and pulmonary artery reconstruction combined with resection and reconstruction of carina and superior vane cava, or combined with superior vena cava and left atrium, or with carina and left atrium was performed in 55 cases in this series. Five patients died of operative complications and the operative mortality was 0.97%. CK19 mRNA expression was found in 141 patients. The positive rate of CK19 mRNA expression was 27.3% in peripheral blood samples in the 516 cases. The positive rates of micrometastasis in peripheral blood was significantly related to histological classification, P-TNM staging and N staging of the cancer (P < 0.05), but not to age, sex, smoking status of the patients, and size of primary tumor, and locations of the tumor (P > 0.05). The median survival time was 43.74 months. The 1, 3, 5 and 10 year survival rates of the 516 cases was 89.1%, 39.3%, 19.8% and 10.4%, respectively. The postoperative survival rate was remarkably correlated with micrometastasis in peripheral blood, histological classification of the tumor, size of primary cancer and lymph mode involvement (P < 0.05). The results of multivariable Cox model analysis showed that "personalized molecular P-TNM staging", micrometastasis in peripheral blood, pathological types of the tumor and mediastinal lymph node metastasis of the cancer were the most significant factors for predicting prognosis in the patients with locally advanced nonsmall lung cancer.

CONCLUSIONS

(1) Micrometastasis was existed in peripheral blood of patients with lung cancer, which can not be detected with conventional methods. (2) Detecting of CK19 mRNA expression in peripheral blood in lung cancer patients can be used for diagnosis of micrometastasis of lung cancer and "molecular staging" and "molecular P-TNM staging" for lung cancer patients. It will be helpful for selection of surgical treatment indication, the beneficiary of neoadjuvant chemotherapy and postoperative adjuvant therapy in the patients with locally advanced non-small cell lung cancer. (3) Personalized surgical treatment can significantly improve prognosis and increase curative rate and long-term survival rate of locally advanced nonsmall cell lung cancer based on personalized molecular staging.

Clinicopathological factors are predictors of distant metastasis from major salivary gland carcinomas

The risk of distant metastasis of salivary gland cancers has usually been associated with histological type, tumour size, and site. The aim of this study was to evaluate a series of patients with major salivary gland carcinomas in order to identify potential risk factors associated with distant metastasis. 255 patients treated for major salivary gland carcinoma in Brazil from 1953 to 2004 were reviewed. Clinical and treatment data were obtained from the medical records and histological features reviewed. 57 (22%) of 255 patients had distant metastasis. The lungs were the most common metastatic site (40 cases, 65%) and adenoid cystic carcinoma the most frequent histological type involved (27 cases, 47%). The percentage of tumours in the submandibular, parotid, and sublingual glands that presented distant metastasis was 42%, 20%, and 17%, respectively. These results provide evidences that clinicopathological factors (tumour site and histology) are significant predictors of distant metastasis in patients with major salivary gland carcinomas.

Cytoplasmic accumulation of connexin32 expands cancer stem cell population in human HuH7 hepatoma cells by enhancing its self-renewal

Although the connexin32 (Cx32)-mediated gap junction is abolished in hepatocellular carcinoma (HCC), the expression of cytoplasmic Cx32 tends to increase in correspondence with the grade of malignancy. Establishing a Tet-off expression system in human nonmetastatic HuH7 HCC cells where cytoplasmic Cx32 was overexpressed by doxycycline (Dox) withdrawal, we previously demonstrated that overexpression of cytoplasmic Cx32 made HuH7 cells metastatic in mice. In our study, hypothesizing that the cytoplasmic Cx32-induced metastasis may involve expansion of the cancer stem cell (CSC) population, we examined whether cytoplasmic Cx32 controlled the size of the side population (SP) in HuH7 Tet-off Cx32 cells. Fluorescence-activated cell sorting revealed that SP was expanded in a Dox-free medium compared with a Dox-supplemented one. Although cytoplasmic Cx32 did not block maturation from SP to non-SP, purified SP reconstituted a larger SP fraction in the Dox-free medium than in the Dox-supplemented one. Furthermore, although SP from HuH7 Tet-off mock cells formed a similar number of CSC spheres of a similar size whether with or without Dox, SP from HuH7 Tet-off Cx32 cells developed a greater number of larger CSC spheres in the Dox-free medium than in the Dox-supplemented one. Taken together, these results suggest that accumulation of cytoplasmic Cx32 should enhance self-renewal of CSC to expand the CSC population in HCC.

Optical techniques for tracking multiple myeloma engraftment, growth, and response to therapy

Multiple myeloma (MM), the second most common hematological malignancy, initiates from a single site and spreads via circulation to multiple sites in the bone marrow (BM). Methods to track MM cells both in the BM and circulation would be useful for developing new therapeutic strategies to target MM cell spread. We describe the use of complementary optical techniques to track human MM cells expressing both bioluminescent and fluorescent reporters in a mouse xenograft model. Long-term tumor growth and response to therapy are monitored using bioluminescence imaging (BLI), while numbers of circulating tumor cells are detected by in-vivo flow cytometry. Intravital microscopy is used to detect early seeding of MM cells to the BM, as well as residual cancer cells that remain in the BM after the bulk of the tumor is eradicated following drug treatment. Thus, intravital microscopy provides a powerful, albeit invasive, means to study cellular processes in vivo at the very early stage of the disease process and at the very late stage of therapeutic intervention when the tumor burden is too small to be detected by other imaging methods.

Long-term follow-up of bladder cancer patients with disseminated tumour cells in bone marrow

BACKGROUND

The clinical relevance of polymerase chain reaction (PCR)-based techniques for detection of disseminated tumour cells (DTCs) in the bone marrow of bladder cancer (BCa) patients is still under debate, as data on long-term follow-up analysis have not yet been published.

OBJECTIVE

The aim of the present prospective study was to assess the prognostic significance of DTCs detected by cytokeratin-20 (CK20) reverse-transcriptase PCR in bone marrow from BCa patients undergoing radical cystectomy (RC).

DESIGN, SETTING, AND PARTICIPANTS

Bone marrow samples from 51 BCa patients with high-risk non-muscle-invasive or muscle-invasive urothelial carcinoma were drawn from the anterior iliac crest prior to RC. CK20-positive cells in bone marrow were detected by qualitative RT-PCR.

MEASUREMENTS

BCa patients with CK20 status were analysed with respect to the end points tumour progression and cancer death. A multivariate Cox regression analysis was performed to determine independent prognostic factors for progression-free survival (PFS), tumour-specific survival (TSS), and overall survival (OS).

RESULTS AND LIMITATIONS

CK20-positive cells were detected in 16 of 51 (31.4%) BCa patients of all stages. BCa patients with CK20-negative status displayed a 7-yr PFS rate of 64% versus 35.2% for CK20-positive patients (p=0.007). TSS was significantly shorter in the CK20-positive group, with a 7-yr survival rate of 46.9% compared to CK20-negative patients with 70.2% (p=0.012). The 7-yr OS rate of 37.5% for CK20-positive patients was significantly <65.7% in the CK20-negative group (p=0.006). A subgroup analysis of lymph node-negative patients (pN0) discriminated by CK20 status revealed significant differences in PFS, TSS, and OS. In a multivariate analysis, CK20-status provides independent prognostic information with respect to all three survival end points.

CONCLUSIONS

BCa patients with positive CK20 status in bone marrow represent a high-risk subgroup reflected by an unfavourable outcome in the long-term analysis.

Advancing personalized cancer therapy by detection and characterization of circulating carcinoma cells

Early dissemination, blood circulation, or homing of single tumor cells in bone marrow and other organs is usually undetectable at primary diagnosis, even by high resolution imaging technologies. However, ultrasensitive approaches now enable the detection of "occult" tumor cells. Many researchers are currently focusing on circulating tumor cells (CTC) in peripheral blood, and several publications have described associations of CTC in patients with metastatic cancer and worse prognosis. However, evidence has emerged that the currently used detection methods lack sensitivity or specificity to track all CTC, especially those that have lost characteristic epithelial features. Therefore, new developments in this field are of utmost interest and will be reviewed here. Moreover, molecular CTC analysis will provide insights into the selection of tumor cells and resistance mechanisms in patients undergoing systemic therapies. This information might support assessing individual prognosis, stratifying patients at risk to systemic therapies, and monitoring therapeutic efficacy.

Quantum dot loaded immunomicelles for tumor imaging

Background

Optical imaging is a promising method for the detection of tumors in animals, with speed and minimal invasiveness. We have previously developed a lipid coated quantum dot system that doubles the fluorescence of PEG-grafted quantum dots at half the dose. Here, we describe a tumor-targeted near infrared imaging agent composed of cancer-specific monoclonal anti-nucleosome antibody 2C5, coupled to quantum dot (QD)-containing polymeric micelles, prepared from a polyethylene glycol/phosphatidylethanolamine (PEG-PE) conjugate. Its production is simple and involves no special equipment. Its imaging potential is great since the fluorescence intensity in the tumor is twofold that of non-targeted QD-loaded PEG-PE micelles at one hour after injection.

Methods

Para-nitrophenol-containing (5%) PEG-PE quantum dot micelles were produced by the thin layer method. Following hydration, 2C5 antibody was attached to the PEG-PE micelles and the QD-micelles were purified using dialysis. 4T1 breast tumors were inoculated subcutaneously in the flank of the animals. A lung pseudometastatic B16F10 melanoma model was developed using tail vein injection. The contrast agents were injected via the tail vein and mice were depilated, anesthetized and imaged on a Kodak Image Station. Images were taken at one, two, and four hours and analyzed using a methodology that produces normalized signal-to-noise data. This allowed for the comparison between different subjects and time points. For the pseudometastatic model, lungs were removed and imaged ex vivo at one and twenty four hours.

Results

The contrast agent signal intensity at the tumor was double that of the passively targeted QD-micelles with equally fast and sharply contrasted images. With the side views of the animals only tumor is visible, while in the dorsal view internal organs including liver and kidney are visible. Ex vivo results demonstrated that the agent detects melanoma nodes in a lung pseudometastatic model after a 24 hours wash-out period, while at one hour, only a uniform signal is detected.

Conclusions

The targeted agent produces ultrabright tumor images and double the fluorescence intensity, as rapidly and at the same low dose as the passively targeted agents. It represents a development that may potentially serve to enhance early detection for metastases.

New advances on critical implications of tumor- and metastasis-initiating cells in cancer progression, treatment resistance and disease recurrence

Accumulating lines of experimental evidence have revealed that the malignant transformation of multipotent tissue-resident adult stem/progenitor cells into cancer stem/progenitor cells endowed with a high self-renewal capacity and aberrant multilineage differentiation potential may be at origin of the most types of human aggressive and recurrent cancers. Based on new cancer stem/progenitor cell concepts of carcinogenesis, it is suggested that a small subpopulation of highly tumorigenic and migrating cancer stem/progenitor cells, also designated as cancer- and metastasis-initiating cells, can provide critical roles for primary tumor growth, metastases at distant tissues and organs, treatment resistance and disease relapse. Particularly, cancer initiation and progression to locally invasive and metastatic stages is often associated with a persistent activation of distinct developmental signaling pathways in these immature cells during epithelial-mesenchymal transition program. The signaling cascades that are often deregulated in cancer stem/progenitor cells include hedgehog, epidermal growth factor receptor (EGFR), Wnt/beta-catenin, NOTCH, polycomb gene product BMI-1 and/or stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor 4 (CXCR4). Importantly, the results from recent investigations have also indicated that different cancer subtypes may harbor distinct subsets and/or number of cancer-initiating cells during cancer progression as well as before or after therapy initiation and disease recurrence. Therefore, the identification of the molecular transforming events that frequently occur in cancer- and metastasis-initiating cells versus their differentiated progenies is of immense interest to develop new targeting approach for improving current therapies against aggressive, metastatic, recurrent and lethal cancers.

EGFR signaling in breast cancer: bad to the bone

The epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptor tyrosine kinases. This family includes EGFR/ErbB1/HER1, ErbB2/HER2/Neu ErbB3/HER3, and ErbB4/HER4. For many years it was believed that EGFR plays a minor role in the development and progression of breast malignancies. However, recent findings have led investigators to revisit these beliefs. Here we will review these findings and propose roles that EGFR may play in breast malignancies. In particular, we will discuss the potential roles that EGFR may play in triple-negative tumors, resistance to endocrine therapies, maintenance of stem-like tumor cells, and bone metastasis. Thus, we will propose the contexts in which EGFR may be a therapeutic target.

EGFR signaling in breast cancer: bad to the bone

The epidermal growth factor receptor (EGFR) is a member of the ErbB family of receptor tyrosine kinases. This family includes EGFR/ErbB1/HER1, ErbB2/HER2/Neu ErbB3/HER3, and ErbB4/HER4. For many years it was believed that EGFR plays a minor role in the development and progression of breast malignancies. However, recent findings have led investigators to revisit these beliefs. Here we will review these findings and propose roles that EGFR may play in breast malignancies. In particular, we will discuss the potential roles that EGFR may play in triple-negative tumors, resistance to endocrine therapies, maintenance of stem-like tumor cells, and bone metastasis. Thus, we will propose the contexts in which EGFR may be a therapeutic target.

Imaging and 'omic' methods for the molecular diagnosis of cancer

Molecular imaging methods can noninvasively detect specific biological processes that are aberrant in cancer, including upregulated glycolytic metabolism, increased cellular proliferation and altered receptor expression. PET using the glucose analogue 18F-fluoro-2-deoxyglucose, which detects the increased glucose uptake that is a characteristic of tumor cells, has been widely used in the clinic to detect tumors and their responses to treatment; however, there are many new PET tracers being developed for a wide range of biological targets. Magnetic resonance spectroscopy (MRS), which can be used to detect cellular metabolites, can also provide prognostic information, particularly in brain, breast and prostate cancers. An emerging technique, which by hyperpolarizing 13C-labeled cell substrates dramatically enhances their sensitivity to detection, could further extend the use of MRS in molecular imaging in the clinic. Molecular diagnostics applied to serum samples or tumor samples obtained by biopsy, can measure changes at the individual cell level and the underlying changes in gene or protein expression. DNA microarrays enable high-throughput gene-expression profiling, while mass spectrometry can detect thousands of proteins that may be used in the future as biomarkers of cancer. Probing molecular changes will aid not only cancer diagnosis, but also provide tumor grading, based on gene-expression analysis and imaging measurements of cell proliferation and changes in metabolism; staging, based on imaging of metastatic spread and elevation of protein biomarkers; and the detection of therapeutic response, using serial molecular imaging measurements or monitoring of serum markers. The present article provides a summary of the molecular diagnostic methods that are currently being trialed in the clinic.

Dynamic reversibility of hydrodynamic focusing for recycling sheath fluid

The phenomenon of "unmixing" has been demonstrated in microfluidic mixers, but here we manipulate laminar flow streams back to their original positions in order to extend the operational utility of an analytical device where no mixing is desired. Using grooves in the channel wall, we passively focus a sample stream with two sheath streams to center it in a microchannel for optical analysis. Even though the sample stream is completely surrounded by sheath fluid, reversing the orientation of the grooves in the channel walls returns the sample stream to its original position with respect to the sheath streams. We demonstrate the separation of the sample stream from the contiguous sheath streams and the recycling of the sheath fluid using the reversibility of laminar flow. Polystyrene microspheres and fluorescent dye were used to quantify the performance of the unsheathing process. We found that the maximum numbers of microspheres and all of the fluorescent dye were recaptured at sheath recycling levels <92%. The use of this sheathing technique has previously been demonstrated in a sensitive microflow cytometer; the unsheathing capability now provides the opportunity to recover particles from the sensor with minimal dilution or to recycle the sheath fluid for long-term unattended operation.

Circulating tumour cells in cancer patients: challenges and perspectives

Ultrasensitive methods have been recently developed to detect circulating tumour cells (CTCs) in the peripheral blood and disseminated tumour cells (DTCs) in the bone marrow (BM) of cancer patients. Studies with these new methods indicate that BM is a common homing organ and a reservoir for DTCs derived from various organ sites including breast, prostate, lung and colon. Peripheral blood analyses, however, are more convenient for patients than invasive BM sampling and many research groups are currently assessing the clinical utility of CTCs for prognosis and monitoring response to systemic therapies. Moreover, molecular analyses of CTCs/DTCs have provided new insights into the biology of metastasis with important implications for the clinical management of cancer patients.

The prognostic value of lymph node ratio in a population-based collective of colorectal cancer patients

OBJECTIVE

We analyzed 3 previously identified cut-off values of lymph node ratios (0.17, 0.41, and 0.69) in a large population-based collective of patients with colorectal cancer for their prognostic value.

SUMMARY BACKGROUND DATA

The lymph node ratio (LNR) (relation of tumor-infiltrated to total examined lymph nodes) has a high prognostic impact, but the relevant cut-off values are not determined.

METHODS

Patients (N = 27,803) with a primary colorectal cancer diagnosed and operated in the Munich region between 1991 and 2006 were registered in the Munich Cancer Registry. Lymph node numbers and survival data were available for 17,309 patients with a mean follow-up of 5.9 years.

RESULTS

The mean number (+/-SD) of resected lymph nodes was 16.8 +/- 8.4. Twelve or more lymph nodes were resected in 76.8%. Estimated 5-year overall survival decreased significantly with increasing LNR: LNR = 0 in 71.4%, LNR 0.01 to 0.17 in 52.4%, LNR 0.18 to 0.41 in 33.3%, LNR 0.42 to 0.69 in 19.8%, and LNR > or = 0.70 in 8.3% (P < 0.001). Multivariable survival analyses identified separately both LNR and pN- category, as well as number of resected lymph nodes, patient's age, tumor location, pT-category, pM-status, R-status, tumor grade, and year of operation as independent prognostic factors.

CONCLUSION

: The 3 cut-off values of LNRs had strong independent prognostic value in a population-based collective of patients with colorectal cancer. The LNR should be routinely reported and included in the American Joint Committee on Cancer staging system. Nevertheless, the benefit of lymphadenectomy on survival is still unclear.

Novel therapies against aggressive and recurrent epithelial cancers by molecular targeting tumor- and metastasis-initiating cells and their progenies

A growing body of experimental evidence has revealed that the highly tumorigenic cancer stem/progenitor cells endowed with stem cell-like properties might be responsible for initiation and progression of numerous aggressive epithelial cancers into locally invasive, metastatic and incurable disease states. The malignant transformation of tissue-resident adult stem/progenitor cells or their progenies into tumorigenic and migrating cancer stem/progenitor cells and their resistance to current cancer therapies have been associated with their high expression levels of specific oncogenic products and drug resistance-associated molecules. In this regard, we describe the tumorigenic cascades that are frequently activated in cancer stem/progenitor cells versus their differentiated progenies during the early and late stages of the epithelial cancer progression. The emphasis is on the growth factor signaling pathways involved in the malignant behavior of prostate and pancreatic cancer stem/progenitor cells and their progenies. Of clinical interest, the potential molecular therapeutic targets to eradicate the tumor- and metastasis-initiating cells and their progenies and develop new effective combination therapies against locally advanced and metastatic epithelial cancers are also described.

Epithelial-to-mesenchymal transitions and circulating tumor cells

Epithelial-to-mesenchymal transition (EMT) phenomena endow epithelial cells with enhanced migratory and invasive potential, and as such, have been implicated in many physiological and pathological processes requiring cell migration/invasion. Although their involvement in the metastatic cascade is still a subject of debate, data are accumulating to demonstrate the existence of EMT phenotypes in primary human tumors, describe enhanced metastatic potential of EMT derivatives in animal models, and report EMT attributes in circulating tumor cells (CTCs). The relationships between EMT and CTCs remain largely unexplored, and we review here in vitro and in vivo data supporting a putative role of EMT processes in CTC generation and survival.

Marker expression in circulating cancer cells of pancreatic cancer patients

BACKGROUND

By the time patients are diagnosed with pancreatic cancer, circulating cancer cells probably exist. Therefore, the detection of pancreatic cancer cells in the peripheral circulation could be used to diagnose early pancreatic cancer, which would otherwise not be detected by current imaging methods.

METHODS

The expression levels of h-TERT, CK20, CEA, and C-MET were detected in a model of circulating micrometastasis in pancreatic cancer that were enriched using immune-magnetic separation of the circulating cancer cells. The sensitivity and specificity of the measurements were evaluated. The expression of the above genes was measured in the circulating cancer cells of pancreatic cancer patients. We compared their expression rate in pancreatic cancer patients at different stages to screen for the indicator with highest sensitivity and specificity for the detection of circulating pancreatic cancer cells.

RESULTS

Immuno-magnetic nanoparticles combined with RT-PCR enabled the detection of one tumor cell per 1×10(7) peripheral blood mononuclear cells. The positive expression rates of C-MET, h-TERT, CK20, and CEA in the pancreatic cancer group were 80% (20/25), 100% (25/25), 84% (21/25), and 80% (20/25), respectively, while in the benign disease control group the rates were 0% (0/15), 0% (0/15), 6.77% (1/15), and 0% (0/15), respectively. There was a significant difference in the positive expression rate between the two groups (P<0.05). The specificity of h-TERT, CEA, and C-MET was higher than that of CK20. The positive expression rate of the four genes was not related to gender, age, tumor size, CA 19-9, or CEA serum levels (P>0.05). However, the positive expression of C-MET, CK20, and CEA closely correlated with tumor stage (P<0.05). Immuno-magnetic nanoparticles combined with RT-PCR were specific and sensitive for the detection of circulating cancer cells.

CONCLUSIONS

The positive expression of C-MET, h-TERT, CK20, and CEA in the circulation of pancreatic patients could be used as an indicator for circulating cancer cells. The combined detection of the four genes improved the specificity and sensitivity to 100%, which may be attributable to the use of immuno-magnetic separation and enrichment of the circulating pancreatic cancer cells. Our results suggest the clinical utility of this approach.

Understanding micrometastatic disease and Anoikis resistance in ewing family of tumors and osteosarcoma

Detection of micrometastatic tumor cells in the bone marrow or peripheral blood of patients with Ewing family of tumors (EFTs) and osteosarcoma has been shown to correlate with poor outcome. Although one of the aims of chemotherapy is eradication of micrometastatic disease, these cells vary phenotypically from primary tumor cells and appear to be more resistant to chemotherapy. As a barrier to metastasis, cells normally undergo a form of cell death termed anoikis after they lose contact with the extracellular matrix or neighboring cells. Tumor cells that acquire malignant potential have developed mechanisms to resist anoikis and thereby survive after detachment from their primary site and while traveling through the circulation. Investigating mechanisms of resistance to anoikis, therefore, provides a valuable model to investigate regulation of micrometastatic disease. This review focuses on the current understanding of the mechanisms involved in mediating cell survival and resistance to anoikis in EFTs and osteosarcoma and discusses future studies that may help to identify novel therapeutics targeted at micrometastatic disease.

Transmission of donor melanoma by organ transplantation

Transplant-related malignancies are a major contributor to morbidity and mortality in the organ-recipient population, and most often develop de novo in the immunosuppressed recipient or as recurrent malignancy after transplantation. The least common scenario, and a rare event, is a recipient malignancy derived from the donor organ. Melanoma is one of the most often reported and lethal donor-derived malignancies with a high transmission rate. Donor transmission of melanoma might be related to the biology of melanoma, with regard to tumour dormancy, late recurrence, circulating tumour cells, and the destiny of some micrometastases. Melanoma-cell dormancy explains the late recurrence that can occur after the initial treatment of melanoma, and may be relevant to our understanding and management of some melanoma micrometastasis in the sentinel node. The high incidence of circulating tumour cells in early melanoma should be considered in the context of the transmission of melanoma by apparent disease-free organ donors following removal of a primary melanoma up to 32 years before. This scenario suggests that melanoma cells can remain dormant at distant sites for decades (and possibly forever) in immunocompetent patients, only to reactivate after transplantation into an immunosuppressed recipient. Potential organ donors should be carefully screened for a history of melanoma, and excluded. The current recommendation for treatment of donor-related melanoma includes withdrawal of immunosuppression, graft rejection, and explantation of the allograft after rejection has been established. In non-renal transplant patients with life-sustaining organs, withdrawal of immunosuppression and graft rejection is not feasible, and reduction of immunosuppression or urgent retransplantation are the only possible salvage strategies. The transmission of malignancy by organ donation could be considered "nature's own experiment", but raises questions that our current understanding of the biology of melanoma cannot answer.

Stem cells as vectors for antitumour therapy

Recent research suggests that mesenchymal stem cells (MSCs) are able to migrate specifically to tumours and their metastases throughout the body. This has led to considerable excitement about the possibility of modifying these cells to express anticancer molecules and using them as specific targeted anticancer agents. However, there are concerns that systemically delivered MSCs may have non-desirable effects, and there are also many unanswered questions including the mechanism of tumour homing. This review investigates the different MSC-delivered anticancer agents, addresses the questions and concerns, and tries to place this potential therapy in future cancer management.

Meta-analysis shows that detection of circulating tumor cells indicates poor prognosis in patients with colorectal cancer

BACKGROUND & AIMS

The prognostic significance of circulating (CTCs) and disseminated tumor cells in patients with colorectal cancer (CRC) is controversial. We performed a meta-analysis of available studies to assess whether the detection of tumor cells in the blood and bone marrow (BM) of patients diagnosed with primary CRC can be used as a prognostic factor.

METHODS

We searched the Medline, Biosis, Science Citation Index, and Embase databases and reference lists of relevant articles (including review articles) for studies that assessed the prognostic relevance of tumor cell detection in the peripheral blood (PB), mesenteric/portal blood (MPB), or BM of patients with CRC. Meta-analyses were performed using a random effects model, with hazard ratio (HR) and 95% confidence intervals (95% CIs) as effect measures.

RESULTS

A total of 36 studies, including 3094 patients, were eligible for final analyses. Pooled analyses that combined all sampling sites (PB, MPB, and BM) associated the detection of tumor cells with poor recurrence-free survival (RFS) (HR = 3.24 [95% CI: 2.06-5.10], n = 26, I(2) = 77%) and overall survival (OS) (2.28 [1.55-3.38], n = 21, I(2) = 66%). Stratification by sampling site showed that detection of tumor cells in the PB compartment was a statistically significant prognostic factor (RFS: 3.06 [1.74-5.38], n = 19, I(2) = 78%; OS: 2.70 [1.74-4.20], n = 16, I(2) = 59%) but not in the MPB (RFS: 4.12 [1.01-16.83], n = 8, I(2) = 75%; OS: 4.80 [0.81-28.32], n = 5, I(2) = 82%) or in the BM (RFS: 2.17 [0.94-5.03], n = 4, I(2) = 78%; OS: 1.50 [0.52-4.32], n = 3, I(2) = 84%).

CONCLUSION

Detection of CTCs in the PB indicates poor prognosis in patients with primary CRC.

Clinical impact of different detection methods for disseminated tumor cells in bone marrow of patients undergoing surgical resection of colorectal liver metastases: a prospective follow-up study

Background

Large number of patients with colorectal liver metastasis show recurrent disease after curative surgical resection. Identification of these high-risk patients may guide therapeutic strategies. The aim of this study was to evaluate whether the presence of disseminated tumor cells in bone marrow from patients undergoing surgical resection of colorectal liver metastases can predict clinical outcome.

Methods

Sixty patients with colorectal liver metastases were planned for a curative resection between 2001 and 2007. All patients underwent bone marrow aspiration before surgery. Detection of tumor cells was performed using immunocytochemical staining for cytokeratin (CK-ICC) combined with automated microscopy or indirectly using reverse transcription-polymerase chain reaction (RT-PCR).

Results

Disseminated tumor cells were found in 15 of the 46 patients (33%) using CK-ICC and in 9 of 44 of the patients (20%) using RT-PCR. Patients with negative results for RT-PCR had a significant better disease-free survival after resection of their liver metastases (p = 0.02). This group also showed significant better overall survival (p = 0.002). CK-ICC did not predict a worse clinical outcome.

Conclusions

The presence of disseminated tumor cells in bone marrow detected using RT-PCR did predict a worse clinical outcome. The presence of cells detected with CK-ICC did not correlate with poor prognosis.

Prognostic significance of circulating tumour cells following surgical resection of colorectal cancers: a systematic review

Background:

The role of adjuvant chemotherapy after resection of colorectal cancers (CRCs) is well understood for patients with stage-I or stage-III disease. Its efficacy for those with stage-II disease remains much less clear. Many investigators have sought to identify prognostic markers that might clarify which patients have the highest risk of recurrence and would, therefore, be most likely to benefit from chemotherapy. This systematic review examines evidence for the use of peripherally sampled, circulating tumour cells (CTCs) as such a prognostic marker.

Methods:

A comprehensive literature search was used to identify studies reporting on the significance of CTCs in the postoperative blood of CRC patients.

Results:

Fourteen studies satisfied the inclusion criteria. Six of the nine studies that took blood samples 24 h or more postoperatively found detection of postoperative CTCs to be an independent predictor of cancer recurrence.

Conclusion:

The presence of CTCs in peripheral blood at least 24 h after resection of CRCs is an independent prognostic marker of recurrence. Further studies are needed to clarify the optimal time point for blood sampling and determine the benefit of chemotherapy in CTC-positive patients with stage-II disease.

Molecular mechanisms underlying tumor dormancy

Evidence suggests that dormant, microscopic tumors are not only common, but are highly prevalent in otherwise healthy individuals. Due to their small size and non-invasive nature, these dormant tumors remain asymptomatic and, in most cases, undetected. With advances in diagnostic imaging and molecular biology, it is now becoming clear that such neoplasms can remain in an asymptomatic, dormant stage for considerable periods of time without expanding in size. Although a number of processes may play a role in thwarting the expansion of microscopic tumors, one critical mechanism behind tumor dormancy is the ability of the tumor population to induce angiogenesis. Although cancer can arise through multiple pathways, it is assumed that essentially most tumors begin as microscopic, non-angiogenic neoplasms which cannot expand in size until vasculature is established. It is now becoming clear that cancer does not progress through a continuous exponential growth and mass expansion. Clinical cancer is usually manifested only in late, unavoidably symptomatic stages of the disease when tumors are sufficiently large to be readily detected. While dormancy in primary tumors is best defined as the time between the carcinogenic transformation event and the onset of inexorable progressive growth, it can also occur as minimal residual or occult disease from treated tumors or as micro-metastases. The existence of dormant tumors has important implications for the early detection and treatment of cancer. Elucidating the regulatory machinery of these processes will be instrumental in identifying novel early cancer biomarkers and could provide a rationale for the development of dormancy-promoting tumor therapies. Despite the high prevalence of microscopic, dormant tumors in humans and the significant clinical implications of their early detection, this area in cancer research has, to date, been under-investigated. In this mini review observations, models and experimental approaches to study tumor dormancy are summarized. Additionally, analogies and distinctions between the concepts of "tumor dormancy" and that of the "cellular dormancy" of tumor cells, as well as between the "exit from tumor dormancy" and the "onset of the angiogenic switch" are discussed.

Blood and tissue biomarkers in prostate cancer: state of the art

The prevalence of prostate cancer (PCa) is high and increases with age. PCa is the most common cutaneous cancer in American men. Prostate-specific antigen (PSA) screening has impacted the detection of PCa and is directly responsible for a dramatic decrease in stage at diagnosis. Gleason score and stage at the time of diagnosis remain the mainstay to predict prognosis, in the absence of more accurate and reliable tissue or blood biomarkers. Despite extensive research efforts, very few biomarkers of PCa have been introduced to date in clinical practice. Even screening with PSA has recently been questioned. A thorough analysis of all tissue and serum biomarkers in prostate cancer research cannot be easily synthesized, and goes beyond the scope of the present article. Therefore the authors focus here on the most recently reported tissue and circulating biomarkers for PCa whose application in clinical practice is either current or expected in the near future.

Comparative evaluation of cell-free tumor DNA in blood and disseminated tumor cells in bone marrow of patients with primary breast cancer

Introduction

The origin and clinical relevance of circulating cell-free tumor DNA in the blood of cancer patients is still unclear. Here we investigated whether the detection of this DNA is related to bone marrow (BM) micrometastasis and tumor recurrence in breast cancer patients.

Methods

BM aspirates of 81 primary breast cancer patients were analyzed for the presence of disseminated tumor cells (DTC) by immunocytochemistry using the pan-cytokeratin antibody A45-B/B3. PCR-based fluorescence microsatellite analysis was performed for detection of loss of heterozygosity (LOH) at 6 polymorphic markers using cell-free serum DNA. The data were correlated with established risk factors, and patients were followed-up over 6-10 years.

Results

LOH was detected in 33.5% of blood samples. The occurrence of LOH at the entire microsatellite marker set correlated with histopathology (P = 0.05) and grading (P = 0.006) of the primary tumor. The genomic region characterized by marker D9S171 was only affected by LOH in patients with increased tumor stages (pT2-4, P < 0.05) and older age (≥ 55 years, P = 0.05). Kaplan-Meier analysis showed that LOH at D3S1255 (P = 0.009) and D9S171 (P = 0.001) were significantly associated with tumor relapse. In BM, DTC were detected in 39.5% of the patients, and this finding correlated with distant metastases (P < 0.05). Patients with DTC-positive BM had higher DNA yields in their blood than patients with DTC-negative BM (P < 0.05). However, no significant correlations were found between the presence of DTC in BM and the detection of marker-specific LOH on blood DNA.

Conclusions

The detection of LOH on cell-free tumor DNA in blood is unrelated to BM micrometastasis and provides independent information on breast cancer progression.