Immunocytochemical detection of epithelial cells in the bone marrow of primary breast cancer patients: a meta-analysis

Patterns of metastatic spread in early breast cancer

AIMS

The aim of this study was to prospectively investigate metastatic pathways of spread to lymph node versus bone marrow and identify biological characteristics that determine these patterns in early invasive breast cancer.

PATIENTS AND METHODS

In all, 177 patients with early invasive breast cancer underwent surgical extirpation of the primary tumour with sentinel lymph node biopsy (SLNB). Bone marrow (BM) aspiration was performed to screen for cytokeratin-positive cells by immunocytochemistry. Lymphatic spread was assessed by histopathological examination of lymph nodes (LN). A representative subset of 87 tumours was analysed by tissue microarray (TMA) to evaluate expression of markers that potentially influence haematogenous vs. lymphatic spread. Patients were followed up for a median of 54.7 months.

RESULTS

Of the 177 patients, 114 (64%) were BM-/LN-, 38 (22%) BM-/LN+, 19 (11%) BM+/LN- and 6 (3%) BM+/LN+. Multivariate analysis of histopathological characteristics revealed that increasing tumour size was significantly associated with both LN positivity (p = 0.003) and BM positivity (p = 0.01), the presence of lymphovascular invasion significantly correlated with LN+ (p = 0.01), whereas lower histological grade was significantly associated with BM+ (p = 0.03). LN+ and BM+ were non-significantly negatively related to each other. Univariate analysis of the TMA data showed differential expression patterns for several factors; significant differences between effects on the two metastatic pathways (lymphatic vs. haematogenous) were found for expression of CD54 (p = 0.03), osteopontin (p = 0.04), bone sialoprotein (p = 0.04) and CXCR4 (p = 0.009). High expression of CD54, osteopontin and bone sialoprotein (BSP) was positively associated with BM + but was either not associated, or negatively associated, with LN+. High CXCR4 expression was positively associated with LN+ and negatively with BM+. High VEGF-C expression was associated with both LN+ and BM+, although this did not attain statistical significance. Due to the small number of clinical events during clinical follow-up, no associations were identified between metastatic spread patterns, recurrence and/or death.

CONCLUSION

These findings suggest that distinct lymphatic and haematogenous metastatic pathways exist in early breast cancer and that these pathways are governed by specific biological markers.

Prognostic value of hematogenous dissemination and biological profile of the tumor in early breast cancer patients: a prospective observational study

Background

The aim of this study was to investigate the incidence and prognostic value of disseminated tumor cells in bone marrow of breast carcinoma patients with early disease, and to analyze this finding in relation to lymph node involvement, determined by sentinel lymph node (SLN) biopsy analysis, and to prognostic factors of interest.

Methods

104 patients with operable (T < 3 cm) breast cancer and clinically- and sonographically-negative axillary lymph nodes were scheduled for SLN biopsy. Bone marrow aspirates were collected before the start of surgery from both iliac crests, and mononuclear cell layers were separated by density centrifugation (Lymphoprep). Slide preparations were then examined for the presence of disseminated tumor cells by immunocytochemistry with anti-cytokeratin antibodies (A45-B/B3). Lymphoscintigraphy was performed 2 hours after intratumor administration of 2 mCi (74 MBq) of 99mTc colloidal albumin. The SLN was evaluated for the presence of tumor cells by hematoxylin-eosin staining and, when negative, by immunocytochemistry using anti-cytokeratin antibody (CAM 5.2). Survival analyses and comparative analyses were performed on the results of bone marrow determinations, SLN biopsy, and known prognostic factors, including breast cancer subtypes according to the simplified classification based on ER, PR and HER2.

Results

Lymph node and hematogenous dissemination occur in one-third of patients with early-stage breast cancer, although not necessarily simultaneously. In our study, disseminated tumor cells were identified in 22% of bone marrow aspirates, whereas 28% of patients had axillary lymph node involvement. Simultaneous lymph node and bone marrow involvement was found in only 5 patients (nonsignificant). In the survival study (60 months), a higher, although nonsignificant rate of disease-related events (13%) was seen in patients with disseminated tumor cells in bone marrow, and a significant association of events was documented with the known, more aggressive tumor subtypes: triple negative receptor status (21%) and positive ERBB2 status (29%).

Conclusions

Tumor cell detection in bone marrow can be considered a valid prognostic parameter in patients with early disease. However, the classic prognostic factors remain highly relevant, and the newer breast cancer subtypes are also useful for this purpose.

Flow cytometric analysis of CK19 expression in the peripheral blood of breast carcinoma patients: relevance for circulating tumor cell detection

Background

Immunocytochemistry and RT-PCR have been widely used for the detection of circulating tumor cells in patients with breast cancer but their specificity is limited. Our purpose is to utilize a convenient and specific technology to detect circulating tumor cells in breast cancer patients.

Methods

To determine the sensitivity and specificity of our method, A431 cells were serially diluted with human peripheral blood leukocytes and stained with CK19. A total of 73 blood specimens including 25 healthy volunteers and 48 patients with breast carcinoma and benign tumor were tested by flow cytometry to quantify the expression of CK19.

Results

The detectable upper limit of A431 cells was 1 cancer cell among 10⁴ human white blood cells. CK19 was detected in 27% of breast cancer patients but none control gives positive result. The number of cancer cells increased gradually along with the disease stages for it was the least in stage I (0%) and the most in stage IV (1.29%). Fifteen patients were observed during three month chemotherapy after surgery, and most of their CK19 expression levels declined after treatment.

Conclusion

Our research convinces that the detection of CK19 in peripheral blood by flow cytometry is also a specific and feasible method to monitor circulating tumor cells in breast cancer.

Significance of micrometastasis in bone marrow and blood of operable breast cancer patients: research tool or clinical application?

Approximately 25% of breast cancer patients without lymph node metastases develop systemic relapse. A growing body of data supports the notion that hematogenous dissemination of breast cancer cells occurs independently of lymphatic spread of disease; however, current clinical practice does not involve routine analysis of circulating or disseminated cells. Recent studies have documented that both circulating tumor cells (CTCs) within the blood and disseminated tumor cells (DTCs) in bone marrow can be identified using a variety of techniques. It is now clear that the presence of DTCs correlates with subsequent development of clinically evident bone metastases, and a worse outcome from breast cancer. While there are data identifying prognostic significance of CTCs in patients with metastatic breast cancer, there are few data regarding CTCs in operable patients. Factors such as presence of a cancer stem cell phenotype and/or certain microenvironmental conditions are involved in the establishment of distant metastases from a primary breast cancer, emphasizing the need for further studies within this area. The purpose of this report is to review the data regarding CTCs and DTCs in patients with operable breast cancer.

Quality of reporting of cancer prognostic marker studies: association with reported prognostic effect

BACKGROUND

Issues of reported study quality have not been addressed empirically with large-scale data in the cancer prognostic literature.

METHODS

Eight quality measures pertaining to study design and assay methods (i.e., blinding, prospective versus retrospective design, power calculations, outcomes' definitions, time of enrollment, reporting of variables, assay description, and assay reference) were evaluated in cancer prognostic marker studies included in meta-analyses identified in Medline and EMBASE. To be eligible, meta-analyses had to include at least six studies and to examine binary outcomes. We estimated the ratios of relative risks, which compared the overall prognostic effects (summary relative risks) between poor-quality and good-quality studies for each quality item. Between-study heterogeneity was tested with the Q statistic (statistically significant at P<.10). All statistical tests were two-sided.

RESULTS

We identified 20 meta-analyses that included 331 cancer prognostic marker studies published between 1987 and 2005. Only three (0.9%) of the 331 studies presented power calculations, 129 (39.0%) studies stated that analyses were blinded, and 73 (21.5%) stated that they were prospective. Time of enrollment was defined in 232 (70.0%), 234 (70.7%) gave lists of candidate variables, and 254 (76.7%) defined outcomes. The assay used was described in 317 (95.8%), but only 177 (53.5%) provided the assay reference. Estimates of prognostic effects from poor-quality studies varied considerably and could be larger or smaller than summary estimates derived from meta-analyses. Summary ratios of relative risks of poor- versus good-quality studies for the seven quality measures ranged from 0.95 to but 1.26, but none was statistically significantly. There was statistically significant heterogeneity (P<.10) between the ratios of relative risk estimates across meta-analyses for blinding, defining endpoints, and stating variables and assay references.

CONCLUSIONS

Among cancer prognostic marker studies, reporting quality of design and assay information often appears suboptimal, indicating that this literature may be largely unreliable. Given the potential clinical importance of prognostic marker information, improved design and reporting of these studies are warranted.

Prognostic Significance of Disseminated Tumor Cells as Detected by Quantitative Real-Time Reverse-Transcriptase Polymerase Chain Reaction in Patients with Breast Cancer

BACKGROUND

In this study we have validated the feasibility of detecting disseminated tumor cells (DTC) by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) analysis. Bone marrow samples from a large cohort of patients with breast cancer were analyzed for the presence of DTC by immunocytochemistry (ICC) or a molecular-based method.

PATIENTS AND METHODS

Bone marrow samples were collected from 170 patients with breast cancer with stage I-IV disease before the initiation of any local or systemic treatment. Staining for cytokeratin (CK)-positive cells was performed with the Epimet kit. Disseminated tumor cells were also quantified by measuring relative gene expression for CK19 and mammaglobin (MAM) using a quantitative RT-PCR detection method. The mean follow-up time was 30 months. Kaplan-Meier analysis was used for predicting overall survival.

RESULTS

Despite an excellent quantitative correlation and qualitative concordance between ICC and RT-PCR, survival analysis suggested an improved prognostic significance of DTC as detected by quantitative RT-PCR. Univariate survival analysis computed a relative risk of death of 2.87 for women with ICC-positive cells in the bone marrow, as compared with those without positive cells. The relative risk for women with RT-PCR-positive bone marrow was even higher: 3.5 (CK19) and 3.39 (MAM). In multivariate analysis, bone marrow CK19 was a stronger prognostic factor than bone marrow ICC.

CONCLUSION

Reverse-transcriptase polymerase chain reaction-detected DTC is shown to be prognostically significant in untreated patients with breast cancer. Furthermore, it seems to be a more sensitive method for detecting DTC in bone marrow samples when compared with ICC.

Real-time RT-PCR detection of disseminated tumour cells in bone marrow has superior prognostic significance in comparison with circulating tumour cells in patients with breast cancer

This study assessed the ability of real-time reverse transcription–polymerase chain reaction (RT–PCR) analysis to detect disseminated epithelial cells (DEC) in peripheral blood (PB) and bone marrow (BM) of patients with breast cancer (BC). Detection of DEC in BM is an obvious choice in BC, but blood sampling is more convenient. The aim of this study was to evaluate whether the detection of DEC in either PB or BM predicts overall survival (OS). Peripheral blood and BM samples were collected from 148 patients with primary (stage M0, n=116/78%) and metastatic (stage M+, n=32/21%) BC before the initiation of any local or systemic treatment. Peripheral blood of healthy volunteers and BM of patients with a nonmalignant breast lesion or a haematological malignancy served as the control group. Disseminated epithelial cells was detected by measuring relative gene expression (RGE) for cytokeratin-19 (CK-19) and mammaglobin (MAM), using a quantitative RT–PCR detection method. The mean follow-up time was 786 days (+/− 487). Kaplan–Meier analysis was used for predicting OS. By taking the 95 percentile of the RGE of CK-19 (BM: 26.3 and PB: 58.7) of the control group as cutoff, elevated CK-19 expression was detected in 42 (28%) BM samples and in 22 (15%) PB samples. Mammaglobin expression was elevated in 20% (both PB and BM) of the patients with BC. There was a 68% (CK-19) and 75% (MAM) concordance between PB and BM samples when classifying the results as either positive or negative. Patients with an elevated CK-19 or MAM expression in the BM had a worse prognosis than patients without elevated expression levels (OS: log-rank test, P=0.0045 (CK-19) and P=0.025 (MAM)). For PB survival analysis, no statistical significant difference was observed between patients with or without elevated CK-19 or MAM expression (OS: log-rank test, P=0.551 (CK-19) and P=0.329 (MAM)). Separate analyses of the M0 and M+ patients revealed a marked difference in OS according to the BM CK-19 or MAM status in the M+ patient group, but in the M0 group, only MAM expression was a prognostic marker for OS. Disseminated epithelial cells, measured as elevated CK-19 or MAM mRNA expression, could be detected in both PB and BM of patients with BC. Only the presence of DEC in BM was highly predictive for OS. The occurrence of DEC in the BM is probably less time-dependent and may act as a filter for circulating BC cells. The use of either larger volumes of PB or performing an enrichment step for circulating tumour in blood cells might improve these results.

The value of bone marrow aspirates culture for the detection of bone marrow micrometastasis in breast cancer

BACKGROUND

Detection of micrometastasis is an important problem of clinical significance for a better understanding and control of tumor progression, which will improve patients' survival time. Tumor cells in bone marrow (BM) aspirates are indicative of the general disseminative metastasis in patients with early breast cancer and characterization of breast cancers by various tumor markers which are appropriate for the identification of high risk groups.

MATERIALS AND METHODS

Bone marrow aspirates were obtained from 44 breast cancer patients at the time of surgery. To identify micrometastases in bone marrow, an immunocytochemical assay for epithelial cytokeratin (CK) was performed at the second passage after selective culture. Cytokeratin-positive bone marrow disseminated cancer cells were observed in more than 90% of the patients. This high incidence needs further investigation with bigger sample size to confirm. However, these results indicate that this technique can be used as an early diagnostic technique of bone marrow micrometastases in the patient with breast cancer thereby promoting the development of therapeutic strategy. High incidences need further investigation with bigger samples to confirm.