Cytokeratin-19 mRNA-positive circulating tumor cells during follow-up of patients with operable breast cancer: prognostic relevance for late relapse

Detection of cancer before distant metastasis

Background

To establish a distant metastasis (DM) cells must disseminate from the primary tumor and overcome a series of obstacles, the metastatic cascade. In this study we develop a mathematical model for this cascade to estimate the tumor size and the circulating tumor cell (CTC) load before the first metastasis has formed from a primary breast cancer tumor.

Methods

The metastatic cascade is described in discrete steps: 1. local tumor growth; 2. dissemination into circulation; 3. survival in circulation; 4. extravasation into tissue; and 5. growth into a metastasis. The model was built using data and relationships described in the literature to predict the relationship between tumor size and probability of distant metastasis for 38715 patients with surgically removed T_XN_XM₀ primary breast cancer from the Netherlands Cancer Registry. The model was calibrated using primary tumor size, probability of distant metastasis and time to distant metastasis for 1489 patients with stage T_1BN_XM₀ (25% of total patients with T_1BN_XM₀). Validation of the model was done with data for all patients.

Results

From the time to distant metastasis of these 38715 breast cancer patients, we determined a tumor doubling time of 1.7 ± 0.9 months. Fitting the data for 25% of T_1B patients estimates a metastatic efficiency of 1 metastasis formed per 60 million disseminated tumor cells. Validation of the model to data of patients in all T-stages shows good agreement between model and epidemiological data. To reduce the 5-year risk of distant metastasis for T_XN_XM₀ from 9.2% to 1.0%, the primary tumor needs to be detected and removed before it reaches a diameter of 2.7 ± 1.6 mm. At this size, the model predicts that there will be 9 ± 6 CTC/L blood.

Conclusions

To reduce the rate of distant metastasis in surgically treated T_XN_XM₀ breast cancer to 1%, imaging technology will need to be able to detect lesions of 2.7 mm in diameter or smaller. Before CTC detection can be applied in the early disease setting, sensitivity will need to be improved by at least 15-fold and combined with technology that minimizes false positives.

Clinical challenges in the molecular characterization of circulating tumour cells in breast cancer

Blood testing for circulating tumour cells (CTC) has emerged as one of the hottest fields in cancer research. CTC detection and enumeration can serve as a 'liquid biopsy' and an early marker of response to systemic therapy, whereas their molecular characterisation has a strong potential to be translated to individualised targeted treatments and spare breast cancer (BC) patients unnecessary and ineffective therapies. Different analytical systems for CTC detection and isolation have been developed and new areas of research are directed towards developing novel assays for CTC molecular characterisation. Molecular characterisation of single CTC holds considerable promise for predictive biomarker assessment and to explore CTC heterogeneity. The application of extremely powerful next-generation sequencing technologies in the area of CTC molecular characterisation in combination with reliable single CTC isolation opens new frontiers for the management of patients in the near future. This review is mainly focused on the clinical potential of the molecular characterisation of CTC in BC.

Tumour dormancy and clinical implications in breast cancer

The aim of adjuvant therapy in breast cancer is to reduce the risk of recurrence. Some patients develop metastases many years after apparently successful treatment of their primary cancer. Tumour dormancy may explain the long time between initial diagnosis and treatment of cancer, and occurrence of relapse. The regulation of the switch from clinical dormancy to cancer regrowth in locoregional and distant sites is poorly understood. In this review, we report some data supporting the existence of various factors that may explain cancer dormancy including genetic and epigenetic changes, angiogenic switch, microenvironment, and immunosurveillance. A better definition and understanding of these factors should allow the identification of patients at high risk of relapse and to develop new therapeutic strategies in order to improve prognosis.

Recent advances and prospects in the isolation by size of epithelial tumor cells (ISET) methodology

Current technologies to identify and characterize circulating tumor cells (CTCs) and _ circulating tumor microemboli (CTMs) among hundreds of millions of leukocytes in the bloodstream can be classified into tumor-marker-dependent and -independent technology. Isolation by size of epithelial tumor cells (ISET) is a tumor-marker-independent technology, in which CTCs are isolated by filtration without use of tumor-associated markers, as a result of their large size relative to circulating blood leukocytes. ISET allows cytomorphological, immunocytological, and genetic characterization of CTCs and CTMs. It offers a number of advantages, including retention of cell morphology; non-antigen dependence; amenability of cells to further interrogation by immunolabeling, fluorescence in situ hybridization, and RNA/DNA analysis; ability to isolate CTMs; reliability. Therefore, morphological-analysis-based and antigen-independent ISET methodology can yield more accurate and objective characterization of epithelial-mesenchymal transition. We can evaluate efficacy of _chemotherapy and radiotherapy and other cancer-targeting therapies by using xenografts that are suitable models for mechanistic studies of ISET-isolated CTC/CTM biology. In addition, a new _ISET-based device could be designed to increase sensitivity to CTCs/CTMs greatly and reduce the number of CTCs/CTMs directly during the blood flow, thus decreasing the _possibility of tumor recurrence and metastasis while retaining normal blood cells. This article reviews recent advances and prospects in ISET methodology and provides new insights into ISET methodology, with important implications for the clinical management of cancer patients.

Very late relapse in breast cancer survivors: a report of 6 cases

BACKGROUND

Breast cancer is the most common cancer and the leading cause of cancer death among the women worldwide. The risk of local and distant recurrence is the highest during the first two years following the initial treatment. Very late relapse (after 12 years) is uncommon in breast cancer survivors.

METHODS

Herein, we report the characteristics and outcomes of 6 such cases of breast cancer.

RESULTS

The mean age of the patients was 40.1 years (range 30-57) and the mean disease free survival was 19.6 years.

CONCLUSION

Late relapse is not so common in breast cancer but can occur in any stage. Therefore, we suggest life-time follow up for every patient with breast cancer.

Biomarkers characterization of circulating tumour cells in breast cancer patients

Introduction

Increasing evidence supports the view that the detection of circulating tumor cells (CTCs) predicts outcomes of nonmetastatic breast cancer patients. CTCs differ genetically from the primary tumor and may contribute to variations in prognosis and response to therapy. As we start to understand more about the biology of CTCs, we can begin to address how best to treat this form of disease.

Methods

Ninety-eight nonmetastatic breast cancer patients were included in this study. CTCs were isolated by immunomagnetic techniques using magnetic beads labelled with a multi-CK-specific antibody (CK3-11D5) and CTC detection through immunocytochemical methods. Estrogen receptor, progesterone receptor and epidermal growth factor receptor (EGFR) were evaluated by immunofluorescence experiments and HER2 and TOP2A by fluorescence in situ hybridization. We aimed to characterize this set of biomarkers in CTCs and correlate it with clinical-pathological characteristics.

Results

Baseline detection rate was 46.9% ≥ 1 CTC/30 ml threshold. CTC-positive cells were more frequent in HER2-negative tumors (p = 0.046). In patients younger than 50 years old, HER2-amplified and G1-G2 tumors had a higher possibility of being nondetectable CTCs. Heterogeneous expression of hormonal receptors (HRs) in samples from the same patients was found. Discordances between HR expression, HER2 and TOP2A status in CTCs and their primary tumor were found in the sequential blood samples. Less that 35% of patients switched their CTC status after receiving chemotherapy. EGFR-positive CTCs were associated with Luminal tumors (p = 0.03).

Conclusions

This is the largest exploratory CTC biomarker analysis in nonmetastatic BC patients. Our study suggests that CTC biomarkers profiles might be useful as a surrogate marker for therapeutic selection and monitoring since heterogeneity of the biomarker distribution in CTCs and the lack of correlation with the primary tumor biomarker status were found. Further exploration of the association between EGFR-positive CTCs and Luminal tumors is warranted.

DTCs/CTCs in breast cancer: five decades later

Since circulating tumor cells were first reported in 1955, the field has seen major advances in their detection and has established their prognostic impact. Here we review the current evidence for the prognostic and predictive value of circulating tumor cells in metastatic breast cancer. We then evaluate the role of CTCs and DTCs in early stage breast cancer. The weight of the evidence supports the role of CTCs and DTCs as prognostic indicators, however their role in therapy prediction remains unclear. Ongoing trials may provide answers and newer detection methods which improve sensitivity and specificity may have greater impact. At this point, the data does not support incorporation into clinical practice for early breast cancer patients.

CTCs in primary breast cancer (II)

CTCs can be detected by real-time RT-PCR for CK19 mRNA in the blood of early breast cancer patients before the start and after the completion of adjuvant chemotherapy and during adjuvant hormonal therapy and the follow-up. Patients with CK19 mRNA-positive cells both before and after chemotherapy have the worst prognosis with shorter disease-free and overall survival. The same is true for patients who have detectable CK19 mRNA-positive cells despite adjuvant tamoxifen while persistent detection during the follow-up predicts for late disease relapse. Thus CTC monitoring offers the opportunity to evaluate the efficacy of adjuvant therapy and identify those patients who are more likely to benefit from secondary adjuvant treatments.