FAQs about the Maintrac® method
Maintrac® is a laboratory method for quantitative detection of circulating epithelial tumour cells.
WHAT ARE CIRCULATING EPITHELIAL TUMOUR CELLS (CETCS)?
1. Maintrac® is not intended to be used as a diagnostic or screening approach. It may be used for tracking the progression or remission of tumours of epithelial origin through its detection of circulating epithelial tumour cells (CETCs) in the blood. The approach has multiple applications, including helping to inform clinical judgment in the provision of functional or integrative support for patients or clients. If Maintrac® to be used to inform cancer treatment directly, or to monitor the interaction of chemotherapeutic agents with CETCs or CSCs (circulating stem cells), the tests must be overseen by a registered medical practitioner or oncologist.
2. Cancer diagnosis, treatment or advice in connection with treatment can only be given by a registered medical practitioner or oncologist.
Solid tumours can seed tumour cells into peripheral blood. It is now clear that cells are shed from tumours well before the formation of metastases. They can be shed from the tumour at all stages of disease and may remain in the patient’s circulation for lengthy periods. Epithelial antigens called EpCAMs (epithelial cell adhesion molecules) are expressed on cells of epithelial origin, such as from solid tumours. These antigens are not usually found on blood cells. This antigen can be stained with a green fluorescent antibody. The blood cells are also stained with an anti-CD45 antibody. The live EpCAM-positive cells are detected and enumerated microscopically. This is possible with an additional dead/live staining dye called propidium iodide. All cells that the dye is able to enter due to having a permeable membrane are excluded. EpCAM stains all epithelial cells. Normal epithelial cells are also detected if these are present. If the patient has a tumour, it is most likely that the epithelial cells are tumour cells.
Source: M El Sherif et al. Behaviour of Circulating Epithelial Tumor Cells (CETCs) and FISH (Fluorescence In Situ Hybridization) of Epidermal Growth Factor Receptor (EGFR)-gene amplification in lung cancer patients during the course of therapy. Advances in Lung Cancer 2013; 2(1):1-8. Monitoring the changes (increase or decrease) of CETC populations in the bloodstream can be used to inform medical practitioners, oncologists and their respective patients of the patients’ progress and responsiveness to different treatments or treatment combinations.
WHAT IS THE DIFFERENCE BETWEEN TUMOUR CELLS AND EPITHELIAL TUMOUR CELLS (CETCs)?
Tumour cells refer to cells of all tumours, of which there are five main groups, namely carcinoma, sarcoma, leukaemia, lymphoma/myeloma, and brain/spinal cord cancers. Epithelial tumour cells refer only to cells from epithelial tumours, of which the most important group are carcinomas which always originate in epithelial tissues.
CAN PATIENTS ORDER MAINTRAC TESTING DIRECTLY?
No. Patients can only order Maintrac® testing through a registered health professional, who will also be able to provide guidance over the interpretation of results.
WHAT IS THE SIGNIFICANCE OF TRACKING THE DEVELOPMENT OF THE CELL COUNT?
Circulating tumour cells can settle in foreign tissues and grow into metastases. These cells can survive in the body for very long times. The number and growth pattern of circulating tumour cells are increasingly being recognised as an important biomarker of a patient’s progress.
HOW IS THE CELL KILL EFFECTIVENESS OF DIFFERENT AGENTS DETERMINED?
Registered health professionals are able to test the likely relative effectiveness of different agents prior to their clinical use by evaluating cell kill effectiveness in a Maintrac® assay. This assay involves exposing all white cells from the cell pellet of 1 ml Î¼l of blood to different concentrations of the respective agent in medium, where the concentration calculated to be present in the blood of patients under treatment is set as one, and a tenfold lower and a tenfold higher concentration is tested in comparison to the control suspension containing the cells without addition of the agent. Cells are cultured under these conditions for up to nine hours and the cytotoxic effect measured at three, six and nine hours. Cells can be characterized as follows: 1) Live blood cells appearing only in transmitted light with no fluorescence staining; 2) Dead blood cells where the membrane has become permeable showing propidium iodide entering the cell, staining the nucleus red fluorescent; 3) Live epithelial (presumably tumour) cells staining with green fluorescence, preferentially as a cap, due to reactivity with FITC-conjugated anti-EpCAM; 4) Dead CETC with simultaneous green and red fluorescent staining, resulting either in a clear green cap with a red nucleus, or later during nucleic and cell disintegration with an orange combination stain. The numbers of live and dead CETCs are determined at each point in time without and with the indicated concentrations of the therapeutic agent and the percentage increase in dead cells over the control is calculated. Quantitative analysis of the samples at different times after incubation with the respective drugs is performed using the image analysis system of the ScanR (Olympus Hamburg, Germany), allowing repeated scanning of the same area.
A typical example showing typical live and dead epithelial cells is shown in Figure 1 of Rüdiger N, et al. Chemosensitivity Testing of Circulating Epithelial Tumor Cells (CETC) in Vitro: Correlation to in Vivo Sensitivity and Clinical Outcome. Journal of Cancer Therapy, 2013; 4: 597-605.
CAN MAINTRAC IDENTIFY THE TYPE OF CANCER AND ITS DEGREE OF AGGRESSIVENESS
Certain properties of circulating tumour cells may provide an indication of the origin of these cells, but Maintrac® is not a standalone diagnostic test for specific cancer types. However, Maintrac® can be invaluable to help clinicians identify an optimal therapeutic approach as well as monitoring progress over time.
CAN MAINTRAC DETECT METASTASES?
Maintrac® is a monitoring method and therefore is not intended to diagnose the presence or location of metastases. However, as an adjunct to other methods, its reliance on measuring CETCs in the bloodstream means it may be among the most sensitive methods for early detection of a progression towards metastatic disease.
CAN TUMOUR CELLS CHANGE?
Yes, the response pattern of tumour cells can change even during therapy by various mechanisms that are largely unknown. It is therefore very important to test the tumour cells repeatedly for their properties (genes, receptors) during the course of disease.
ARE THERE THRESHOLD VALUES FOR THE CELL COUNT?
Every patient is unique, every tumour is distinct. In this respect, there are no generally accepted critical values. In order to determine an increase or decrease in cell count, at least two tests are necessary.
ARE THERE ANY STUDIES PUBLISHED CONCERNING THE MAINTRAC APPROACH?
The significance of Maintrac® is well documented in studies and published in high-impact journals. The current list of studies can be found here.
CAN THE COURSE OF DISEASE BE MONITORED BY MAINTRAC®?
Yes, by enumerating the tumour cells at specific intervals, the tumour activity throughout the entire course of disease can be monitored. Since the circulating tumour cells can be inactive for a long time, it is important to follow the cell numbers. If the cell count changes, the current therapeutic approach can be promptly adjusted.
IS THE CHEMOSENSITIVITY TEST IN VITRO COMPARABLE TO THE EFFECTIVENESS IN THE PATIENT?
The chemosensitivity test is a laboratory-determined indication of the efficacy of tested agents. The clinical effectiveness of given therapies will typically be related to the concentration of given agents achieved in the blood, tumour and metastases, as well as concomitant treatments or therapies.
DOES AN INCREASE IN THE NUMBER OF CETCs CORRELATE WITH METASTASES?
An increase in the number of CETCs in the blood may indicate growth of the tumour or metastases, and has been shown to correlate highly significantly with progression.
WHAT ARE THE BENEFITS FOR PATIENTS USING MAINTRAC?
Maintrac® is an invaluable clinical tool that enables the practitioner to monitor the patient’s progress and response to clinical, nutritional and lifestyle protocols.
ARE THERE ANY DISADVANTAGES FOR PATIENTS USING MAINTRAC?
When a registered medical practitioner or oncologist uses Maintrac® to monitor cancer progression, some patients are understandably concerned that when cells are found and increase over time, and when they do not respond to specific agents, that this might be a sign of recurrence. In reality, the assay may pick up a change prior to any development of metastasis and this offers the opportunity for the clinician to promptly adjust the therapeutic approach. Whether patients want advance information of this kind is for them to discuss with their practitioner.
WHAT ARE THE PSYCHO-ONCOLOGICAL IMPACTS OF MAINTRAC ON PATIENTS?
A disease like cancer is not easy to bear for patients and their families. Uncertainty as to whether the cancer is now defeated and the fear that it could return are permanent companions. Many patients are grateful for the knowledge that their cell count gives them, enabling them to tolerate the situation better.
WHICH TYPES OF TUMOURS CAN BE DIAGNOSED WITH MAINTRAC?
The possible application of Maintrac® covers solid epithelial tumours (carcinomas, the most common type of cancer). The laboratory will be glad to assist and advise you in the event of other types of tumour.
IS MAINTRAC® JUST ANOTHER TUMOUR MARKER?
Circulating tumour cells can be regarded as direct or primary markers, being, in most cases, epithelial cells found in blood serum from tumours themselves, and not antigens or other proteins released by the tumour cells. Most tumour markers are these secondary markers (e.g. carcinoembryonic antigen (CEA), alpha-fetoprotein, human chorionic gonadotrophin), and as a result can be regarded as indirect markers.
IS THERE ANYTHING I SHOULD BE AWARE OF WHEN MONITORING THE VOLUME OF CIRCULATING TUMOUR CELLS?
It is known that tumour cells can downregulate their antigen expression, including the epithelial surface antigen (EpCAM), during increasingly aggressive growth or the so-called epithelial-mesenchymal transition (EMT). This would imply that they may become less detectable or even undetectable using Maintrac® that uses an antibody against EpCAM to detect cancerous cells in blood. In this case, we not infrequently observe – after an increase in cell numbers – a sudden decrease to below our detection limit. Under these circumstances, Maintrac® recommends that clinicians turn to imaging, and consider using Stemtrac® alongside it, which is used to identify cancer stem cells in blood samples.
We strongly advise that cancer patients remain under the care of their registered medical doctors and oncologists at all times. Cancer diagnosis, treatment or advice in connection with treatment can only be given by a registered medical practitioner or oncologist.