Presence of disseminated tumor cells in bone marrow correlates with tumor stage and nodal involvement in cervical cancer patients.

Detection of disseminated tumor cells (DTCs) in the bone marrow (BM) of breast cancer patients is associated with poor outcome. The aim of our study was to evaluate the impact of BM status on survival in a large cohort of cervical cancer patients. Three hundred twenty-five patients with cervical cancer were included into this prospective two-center study (University Hospitals Tuebingen, Munich, Germany). BM was collected preoperatively. DTCs were identified by immunocytochemistry using the pancytokeratin antibody A45B/B3. DTCs were detected in 22% of all BM aspirates. The number of CK-positive cells ranged from 1 to 93 per 2 × 10(6) mononuclear cells. Eighteen percent of patients with T1 stage presented with DTCs in BM compared to 30% in T2 and 45% in T3/4 patients. Among nodal negative patients, 18% had tumor cells in BM compared to 32% of nodal positive patients. Positive DTC status was associated with tumor size (p = 0.007) and nodal status (p = 0.009) but not with grading (p = 0.426). DTC status did not correlate with overall or disease-free survival. In the univariate analysis, tumor stage, nodal status, resection status and grading correlated with OS and DFS. In the multivariate analysis, only tumor stage and nodal status were independent predictors of OS and tumor stage, nodal status and grading of DFS. Tumor cell dissemination into BM is thus a common phenomenon in cervical cancer and correlates with higher tumor load but lacks prognostic relevance. Alternative detection methods may be needed to establish prognostic potential.

Detection and clinical relevance of hematogenous tumor cell dissemination in patients with ductal carcinoma in situ.

Hematogenous tumor cell dissemination is a crucial step in systemic disease progression and predicts reduced clinical outcome in breast cancer patients. Only invasive cancers are assumed to shed tumor cells into the bloodstream and infiltrate lymph nodes. However, recent studies revealed that disseminated tumor cells (DTCs) may be detected in bone marrow (BM) of patients with preinvasive lesions, i.e., ductal carcinoma in situ (DCIS). The purpose of this analysis was to examine the incidence and clinical value of DTC detection in a large series of patients with pure DCIS. 404 patients treated for DCIS at the University Hospital Tuebingen, Germany were included into this analysis. BM was analyzed by immunocytochemistry (pancytokeratin antibody A45-B/B3) using ACIS system (Chromavision) according to the ISHAGE evaluation criteria. Sentinel nodes were analyzed in 316 patients by step sectioning and hematoxylin-eosin staining. DTCs were detected in 63 of 404 patients (16 %). No correlation was observed between BM status and tumor size, grading, histology or Van Nuys prognostic index. In two cases, metastatic spread into lymph nodes was observed; isolated tumor cells were found in one patient. After a median follow-up of 45 months (range 3-131 months), 3 % of BM positive patients died compared to 1 % of BM negative patients (p = 0.254). Relapse of any kind was observed in 7 % of patients with DTCs vs. 5 % of patients without DTCs (p = 0.644). The differences in overall (p = 0.088) and disease-free survival (p = 0.982) calculated by log-rank test were not statistically significant. Tumor cell dissemination may be detected in patients diagnosed with DCIS. Whether these cells disseminate from real preinvasive mammary lesions or represent the earliest step of microinvasion, remains unclear. A longer follow-up may be necessary to accurately assess clinical value of these cells in DCIS patients.

Prognostic relevance of induced and spontaneous apoptosis of disseminated tumor cells in primary breast cancer patients.

BACKGROUND: An imbalance between cell proliferation and programmed cell death can result in tumor growth. Although most systemic cytotoxic agents induce apoptosis in tumor cells, a high apoptotic rate in primary breast cancer correlates with poor prognosis. The aim of this study was to investigate the incidence and the prognostic significance of apoptotic disseminated tumor cells (DTC) in the bone marrow (BM) of breast cancer patients who either underwent primary surgery or primary systemic chemotherapy (PST). METHODS: A total of 383 primary breast cancer patients with viable DTC in the BM were included into this study. Eighty-five patients were initially treated with primary systemic chemotherapy whereas 298 patients underwent surgery first. Detection of apoptotic DTC were performed by immunocytochemistry using the M30 antibody which detects a neo-epitope expressed after caspase cleavage of cytokeratin 18 during early apoptosis. The median follow up was 44 months (range 10-88 months). RESULTS: Eighty-two of 298 (27%) primary operated patients and 41 of 85 (48%) patients treated with primary systemic systemic therapy had additional apoptotic DTC (M30 positive). In the neoadjuvant group M30-positive patients were less likely to suffer relapse than those without apoptotic DTC (7% vs. 23% of the events, p=0.049). In contrast, the detection of apoptotic DTC in patients treated by primary surgery was significantly associated with poor overall survival (5% vs. 12% of the events, p=0.008). CONCLUSIONS: Apoptotic DTC can be detected in breast cancer patients before and after systemic treatment. The presence of apoptotic DTC in patients with PST may be induced by the cytotoxic agents. Thus, both spontaneous and chemotherapy-induced apoptosis may have different prognostic significance.

Influence of zoledronic acid on disseminated tumor cells in bone marrow and survival: results of a prospective clinical trial.

BACKGROUND: The presence of disseminated tumor cells (DTC) in bone marrow (BM) of breast cancer patients is associated with reduced clinical outcome. Bisphosphonate treatment was shown to eradicate DTC from BM in several studies. This controlled randomized open-label multi-center study aimed to investigate the influence of zoledronic acid (ZOL) on DTC and survival of breast cancer patients (Clinical Trial Registration Number: NCT00172068). METHODS: Patients with primary breast cancer and DTC-positive bone marrow were randomized to treatment with ZOL plus adjuvant systemic therapy (n = 40) or adjuvant systemic therapy alone (n = 46) between 03/2002 and 12/2004. DTC were identified by immunocytochemistry using the pancytokeratin antibody A45B/B3 and by cytomorphology. The change in DTC numbers at 12 months and 24 months versus baseline, as well as patient outcomes were evaluated. RESULTS: 86 patients could be included into survival analysis (median follow-up: 88 months, range: 8-108 mths). Patients in the control group were more likely to die during follow-up than those in the ZOL-group (11% vs. 2%, p = 0.106). 15% of patients in the control group presented with relapse whereas only 8% of ZOL group patients developed metastatic or recurrent disease during follow-up (p = 0.205). At 24 months, 16% of patients from the control group were still DTC positive, whereas all patients treated with ZOL became DTC negative (p = 0.032). Patients presenting with persistent DTC 12 months after diagnosis had significantly shorter overall survival (p = 0.011). CONCLUSIONS: Bisphosphonate therapy contributes to eradication of disseminated tumor cells. The positive influence of bisphosphonates on survival in the adjuvant setting may be due to their effects on DTC. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00172068 [Zoledronic Acid in the Treatment of Breast Cancer With Minimal Residual Disease in the Bone Marrow (MRD-1)].

Pooled analysis of the prognostic relevance of disseminated tumor cells in the bone marrow of patients with ovarian cancer.

OBJECTIVE: Detection of disseminated tumor cells (DTCs) in the bone marrow (BM) of patients with breast cancer is associated with poor outcomes. Recent studies demonstrated that DTCs may serve as a prognostic factor in ovarian cancer. The aim of this 3-center study was to evaluate the impact of BM status on survival in a large cohort of patients with ovarian cancer. MATERIALS AND METHODS: Four hundred ninety-five patients with primary ovarian cancer were included in this 3-center prospective study. Bone marrow aspirates were collected intraoperatively from the iliac crest. Disseminated tumor cells were identified by antibody staining and by cytomorphology. Clinical outcome was correlated with the presence of DTCs. RESULTS: Disseminated tumor cells were detected in 27% of all BM aspirates. The number of cytokeratin-positive cells ranged from 1 to 42 per 2 × 106 mononuclear cells. Disseminated tumor cell status did correlate with histologic subtype but not with any of the other established clinicopathologic factors. The overall survival was significantly shorter among DTC-positive patients compared to DTC-negative patients (51 months; 95% confidence interval, 37-65 months vs 33 months; 95% confidence interval, 23-43 months; P = 0.023). In the multivariate analysis, BM status, International Federation of Gynecology and Obstetrics stage, nodal status, resection status, and age were independent predictors of reduced overall survival, whereas only BM status, International Federation of Gynecology and Obstetrics stage, and resection status independently predicted progression-free survival. CONCLUSIONS: Tumor cell dissemination into the BM is a common phenomenon in ovarian cancer. Disseminated tumor cell detection has the potential to become an important biomarker for prognostication and disease monitoring in patients with ovarian cancer.

The influence of removal of primary tumor on incidence and phenotype of circulating tumor cells in primary breast cancer.

Recent studies have shown that the detection of circulating tumor cells (CTC) pre and postoperatively in the peripheral blood of primary breast cancer patients may be an indicator for poor survival. This study aimed to investigate the influence of removal of the primary tumor on incidence and phenotype of circulating tumor cells in primary breast cancer. 209 primary breast cancer patients could be included into this analysis. Blood sampling was performed both pre and postoperatively. The blood specimens were immunomagnetically enriched using AdnaTest BreastCancerSelect within 4 h after blood withdrawal, followed by RNA isolation and subsequent gene expression analysis by reverse transcription and multiplex PCR using AdnaTest BreastCancerDetect. Three breast cancer-associated tumor markers and two hormone receptor genes were amplified: GA733-2, Muc-1, Her-2, ER, PR. In addition, bone marrow (BM) status was intraoperatively determined. Forty-three of 209 patients (21%) had pre and/or postoperatively circulating tumor cells. The positivity rates after surgery were higher but did not differ significantly (12% pre and 16% postoperatively, P = 0.264). Disseminated tumor cells in BM were seen in 32 of 209 cases (15%). Patients with positive BM status had significantly higher CTC positivity rates both pre and postoperatively compared to those with negative BM status. The most common CTC phenotype was triple negative (24 patients) followed by HER2+/ER-/PR- subtype (10) and ER and/or PR positive (9). Interestingly, 41 of 43 primary tumors (95%) were ER and PR positive. Removal of the primary tumor did not alter the phenotype of CTC. Surgery does not significantly influence the tumor cell load in the blood stream. CTC phenotype before and after the surgery generally remains identical but may differ from that of the primary tumor.

Hematogenous and lymphatic tumor cell dissemination may be detected in patients diagnosed with ductal carcinoma in situ of the breast.

Tumor cell dissemination in bone marrow (BM) and lymph nodes is considered an important step in systemic disease progression and is associated with poor prognosis. Only invasive cancers are assumed to shed isolated tumor cells (ITC) into the bloodstream and infiltrate lymph nodes. However, latest studies indicate that tumor cell dissemination may occur before stroma invasion, i.e., in ductal carcinoma in situ (DCIS). Therefore, the purpose of this study was to examine the incidence of ITC in bone marrow and sentinel lymph nodes (SN) in patients diagnosed with DCIS and its correlation with clinicopathological factors. 266 patients who were treated at the Department of Gynecology and Obstetrics (University Hospital Tuebingen, Germany) between 2003 and 2009 with DCIS were included into this study. BM aspirates were analyzed by immunocytochemistry (pancytokeratin antibody A45-B/B3) using ACIS system (Chromavision) according to the ISHAGE evaluation criteria. SN were analyzed in 221 of these patients by extensive step sectioning and hematoxylin-eosin staining. In 34 of 266 patients (13%), ITC in BM could be detected. There was no correlation found between tumor size, grading, histology, or Van Nuys Prognostic Index and tumor cell dissemination. In two cases, metastatic spread into lymph nodes was observed (pN1mi), whereas in one case, ITC in lymph nodes were detected; however, additional sectioning and immunohistochemical staining of the primary lesion in the cases with positive SN did not reveal invasive cancer. Interestingly, all the three patients were BM negative. Tumor cell dissemination may be detected in patients diagnosed with DCIS. Either these cells have started already to disseminate from preinvasive mammary lesions or from occult invasive tumors or represent the earliest step of microinvasion in a preinvasive lesion. The clinical relevance of these cells has to be further evaluated.

Bone marrow versus sentinel lymph node involvement in breast cancer: a comparison of early hematogenous and early lymphatic tumor spread.

The early spread of tumor cells in primary breast cancer patients may occur either through lymphatic or hematogenous dissemination. Lymph node (LN) status and presence of disseminated tumor cells (DTC) in bone marrow (BM) are independent predictors of poor outcome. It is unknown which factors determine one or the other route of tumor cell spread and whether lymphatic and hematogenous tumor cell dissemination are two independent processes. This study is aimed to compare the DTC status in clinically node-negative (N0) breast cancer patients with their sentinel LN status and to investigate predictors of BM and LN involvement. The DTC status of 1,345 clinically N0 breast cancer patients who underwent SLN biopsy during initial surgery was investigated. BM and LN status were compared and predictors of hematogenous and lymphatic tumor cell spread were investigated. DTCs were present in the BM of 181 (13%) patients. LN involvement was found in 348 (26%) patients. There was no correlation between LN and BM status: 137 of 997 nodal-negative patients (14%) had BM involvement and 44 of 348 nodal-positive patients (13%) were positive for DTCs (P = 0.649). The presence of DTCs was not influenced by tumorbiological factors. Conversely, a high correlation between nodal status and tumor size, histology, ER-status and lymph vessel invasion was found. Hematogenous and lymphatic tumor spread seem to be because of independent pathways of cancer progression.

HER2-positive DTCs/CTCs in breast cancer.

The presence of circulating tumor cells (CTCs) in the blood as well as disseminated tumor cells (DTCs) in the bone marrow of breast cancer patients is associated with a worsened prognosis in the primary as well as in the metastatic situation. Next to their detection, evaluation of human epidermal growth factor receptor (HER2) expression is a valuable feature of CTCs/DTCs. As the HER2 status may change during disease progression CTCs/DTCs might (1) characterize the phenotype of minimal residual disease in the adjuvant setting and (2) serve as a "real time biopsy" of metastatic breast cancer. Phenotyping of CTCs/DTCs will thus help to understand mechanism of resistance to HER2-directed therapy. Moreover, patients that are likely to benefit from HER2-directed therapy despite a HER2-negative primary tumor might be identified. 

[Detection of disseminated tumor cells in the bone marrow of breast cancer patients with a new molecular method]. / Detekcja rozsianych komórek nowotworowych w szpiku kostnym u pacjentek z rakiem piersi z zastosowaniem nowej metody molekularnej.

OBJECTIVES: Numerous studies have shown that the presence of clinically occult disseminated tumor cells (DTC) in the bone marrow (BM) of breast cancer patients is associated with an unfavourable clinical outcome. Immunocytochemistry (ICC) remains the gold standard for their detection. Assays based on RT-PCR are available; however so far they have not been used for routine detection of DTC. Therefore, the purpose of this study was to evaluate a newly established molecular method for the detection of DTC. MATERIALS AND METHODS: BM aspirates from 405 patients were examined. Half of the samples were immediately inserted into ICC and the other half was examined with our newly established molecular method based on RT-PCR. Immunocytochemistry was performed according to the Consensus Recommendations of the German, Austrian, and Swiss Societies of Senology and ISHAGE Working Group (A45B-B3 antibody). RT-PCR was conducted as a one-step real-time assay Cytokeratin 19-mRNA was amplified. RESULTS: In 142 of 405 (35%) aspirates disseminated tumor cells were detected by RT-PCR. In 34% of patients DTC were detected by ICC. 48% of the BM samples were positive by at least one method. In 73% of the patients identical results were obtained (p<0,001). CONCLUSION: Our newly established molecular assay for the detection of disseminated tumor cells, and thus minimal residual disease, is sensitive, fast and reproducible, and has a potential to be used as a confirmatory or alternative test for DTC detection.

Molecular detection of breast cancer metastasis in sentinel lymph nodes by reverse transcriptase polymerase chain reaction (RT-PCR): identifying, evaluating and establishing multi-marker panels.

The potential advantage of using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) methodology to detect metastasis in sentinel lymph nodes (SLNs) of breast cancer (BC) patients was evaluated in this prospective study. We measured the expression of relevant gene transcripts in SLNs using an innovative algorithm and compared the results of single-marker assays versus multi-marker assays with conventional histological detection methods. SLNs from women aged ≥ 18 years diagnosed with unilateral BC were examined by haematoxylin-eosin staining and immunohistochemistry and analysed for transcripts of several relevant genes using qRT-PCR (learning group). Four candidate panels of expressed transcript combinations with high sensitivity and specificity were selected for further investigation. The candidate panels were then validated using SLNs from a second group of BC patients (validation group). In the learning group, 74/314 SLN sections from 150 patients were positive for metastasis by histology. The transcripts analysed showed the following individual sensitivities/specificities: cytokeratin 19 (CK19) 94.6%/97.9%; mammaglobin 1 (MGB1) 82.4%/91.7%; mammaglobin 2 (MGB2) 82.4%/96.7%; carcinoembryonic antigen (CEA) 71.6%/97.5%; EPCAM (epithelial cell adhesion molecule) 91.9%/97.1%; and NY-BR-1 82.4%/93.8%. The optimal panel based on the predefined criteria comprised four markers: CK19, MGB1, EPCAM, and NY-BR-1, of which ≥ 2 had to be positive (95.9% sensitivity, 95.0% specificity, 85.5% positive predictive value (PPV), and 98.7% negative predictive value (NPV)). Overall concordance with histology was 95.2%. In the validation group, 84/315 SLN sections from 235 patients were histologically positive, and panel sensitivity, specificity and overall accuracy were 88.1, 95.2 and 93.3%, respectively, at the SLN section level. In conclusion, molecular staging using expression patterns of relevant transcripts in SLNs could serve as a useful complement to standard diagnostic work-up in BC patients. The proposed flexible multi-parametric approach does not improve the overall accuracy compared with the single-marker approach. However, it overcomes several limitations of the previously reported molecular assays for SLN diagnosis.

Pregnancy after breast cancer: case report and review of the literature.

Despite breast cancer diagnosis and treatment, women of childbearing age often desire a pregnancy. Since the average age of women giving birth for the first time is increasing, many young patients diagnosed with breast cancer have not started or completed their family planning. Thus, gynecologists and oncologists are confronted more often with the question of childbearing after breast cancer. Current data from retrospective trials do not suggest an increased risk of a recurrence or progress of the disease associated with pregnancy after stage-adjusted treatment. Also, the risk of fetal malformations and damage to the fetus after chemotherapy and/or hormone therapy seems similar to that in the general population. Women who receive chemotherapy are advised to wait at least 6 months before they attempt to conceive. The question whether to become pregnant must be discussed individually with the patient, based on tumor characteristics, stage of the disease and patient's wishes.

Optimal treatment for patients with ectopic pregnancies and a history of fertility-reducing factors.

PURPOSE: With most ectopic pregnancy (EP) cases now diagnosed and treated early, a major concern has become future reproductive outcome. The aim of this study was to evaluate long-term reproductive outcome after salpingotomy versus salpingectomy in patients with and without additional fertility-reducing factors. METHODS: As part of a prospective follow-up study, 261 patients underwent laparoscopic management of EP at our institution. History was taken specifically looking at preexisting risk factors for reduced fertility. Patients were then followed with regard to future reproductive events. RESULTS: Of 261 patients, 196 (75%) reported a subsequent desire for pregnancy. 145 patients had undergone salpingotomy and 51 salpingectomy. In patients without prior history of fertility-reducing factors, the subsequent intrauterine pregnancy rates were >90% for both salpingotomy and salpingectomy groups irrespective of the surgical approach. In patients with preexisting fertility-reducing factors, postoperative intrauterine pregnancy rates were 75% in the salpingotomy group, but only 40% in the salpingectomy group (p < 0.05), showing maximal effect for conservative surgery. CONCLUSION: Laparoscopic salpingotomy is of particular benefit for patients with additional fertility-reducing factors desirous of future pregnancy. Reproductive outcome is excellent in patients without such risk factor, irrespective of the surgical approach.

Evaluation of a RT-PCR based routine screening tool for the detection of disseminated epithelial cells in the bone marrow of breast cancer patients.

PURPOSE: Numerous studies have shown that the presence of clinically occult disseminated tumor cells (DTC's) in the bone marrow (BM) of breast cancer patients is associated with an unfavourable clinical outcome. Immunocytochemistry (ICC) remains the gold standard for their detection. While assays based on RT-PCR are available, they have not been used for routine detection of DTC's. METHODS: To assess the quality of the assay, we performed a direct comparison of DTC detection rates in a large cohort of 385 patients using both standardized ICC and real-time RT-PCR protocols. Correlation rates were assessed, and results were compared with clinical data. RESULTS: A significant correlation between ICC and RT-PCR was observed (P < 0.01). Positivity rates were similar (both 35%) and the results of both methods agreed in 73% of cases (280/385). CONCLUSIONS: We describe a real-time RT-PCR based protocol for DTC-detection that has been specifically designed for routine clinical laboratory use. As such, RT-PCR has the potential to become an alternative testing method for BM evaluation in breast cancer patients.

Disseminated tumor cells in bone marrow may affect prognosis of patients with gynecologic malignancies.

INTRODUCTION: The presence of disseminated tumor cells (DTC) in the bone marrow (BM) of breast cancer patients is associated with poor prognosis. Several studies demonstrated that tumor cell dissemination may occur in gynecologic cancer and affect clinical outcome. The aim of our study was to evaluate the incidence of DTC and to assess their prognostic significance in patients with gynecologic malignancies. METHODS: Bone marrow aspirates from 377 patients with primary ovarian (112), endometrial (141), cervical (102), and vulvar cancer (22) undergoing surgery at the Department of Gynecology and Obstetrics, University Hospital, Tuebingen, Germany between November 2001 and November 2007, were included into the study. Disseminated tumor cells were identified by immunocytochemistry using the pancytokeratin antibody A45B/B3 and by cytomorphology. RESULTS: Disseminated tumor cells were detected in 19% of BM aspirates from patients with gynecological malignancies. Incidences of DTC in ovarian, endometrial, cervical, and vulvar cancer were 25%, 16%, 19%, and 5%, respectively. For patients with ovarian and endometrial cancer, no correlation with established clinicopathological factors was observed. In case of cervical cancer, BM positivity was correlated with International Federation of Gynecology and Obstetrics stage, tumor size, and nodal involvement. Bone marrow positivity of ovarian cancer patients was correlated with significantly shorter disease-free survival (P = 0.035). For other tumor entities, no association between BM status and clinical outcome could be observed. CONCLUSIONS: We conclude that up to 25% of patients with loco-regionally restricted gynecologic malignancies present with DTC at the time of diagnosis. For ovarian cancer patients, BM status affected clinical outcome.

The role and clinical relevance of disseminated tumor cells in breast cancer.

Tumor cell dissemination is a common phenomenon observed in most cancers of epithelial origin. One-third of breast cancer patients present with disseminated tumor cells (DTCs) in bone marrow at time of diagnosis; these patients, as well as patients with persistent DTCs, have significantly worse clinical outcome than DTC-negative patients. Since DTC phenotype may differ from the primary tumor with regard to ER and HER2 status, reevaluation of predictive markers on DTCs may optimize treatment choices. In the present review, we report on the clinical relevance of DTC detection in breast cancer.

Expression of stem cell and epithelial-mesenchymal transition markers in circulating tumor cells of breast cancer patients.

Evaluation and characterization of circulating tumor cells (CTCs) have become a major focus of translational cancer research. Presence of CTCs predicts worse clinical outcome in early and metastatic breast cancer. Whether all cells from the primary tumor have potential to disseminate and form subsequent metastasis remains unclear. As part of the metastatic cascade, tumor cells lose their cell-to-cell adhesion and undergo epithelial-mesenchymal transition (EMT) in order to enter blood circulation. During EMT epithelial antigens are downregulated; thus, such tumor cells might elude classical epithelial marker-based detection. Several researchers postulated that some CTCs express stem cell-like phenotype; this might lead to chemoresistance and enhanced metastatic potential of such cells. In the present review, we discuss current data on EMT and stem cell markers in CTCs of breast cancer and their clinical significance.

Circulating tumour cells in breast cancer.

Evaluation of isolated tumour cells in bone marrow (BM) and peripheral blood has become a major focus of translational cancer research. The presence of disseminated tumour cells in BM is a common phenomenon observed in 30-40% of primary breast cancer patients and independently predicts reduced clinical outcome. The detection of circulating tumour cells (CTCs) in blood might become a desired alternative to the invasive and painful BM biopsy. Recent clinical trials confirmed the feasibility of CTC detection as a robust and reproducible parameter for prognostication in both adjuvant and metastatic setting. The characterisation of CTCs might become an important biomarker for therapy monitoring and help to identify specific targets for novel therapeutic strategies.

Circulating tumor cells in breast cancer.

Detection of disseminated tumor cells (DTCs) in bone marrow and of circulating tumor cells (CTCs) in the blood has become a major focus of translational cancer research. DTC presence is a common phenomenon seen in 30-40% of primary breast cancer patients and is strongly associated with poor clinical outcome. Since bone marrow biopsy is an invasive procedure, evaluation of CTCs might become a desired alternative. Recent clinical trials have shown CTC detection to be a promising prognostic tool in both primary and metastatic setting. Evaluation of CTCs might be useful for therapy monitoring and their characterization might help to identify novel targets for biological therapies aimed at disrupting earliest steps of metastatic cascade.