The disease is said to have reached a metastatic stage when secondary tumors (metastases) form in the body.
In order to destroy or shrink the metastases as well as the circulating tumor cells, systematic therapies are often used during the metastatic stage. For this, the most effective drug for each individual patient should be used.
By taking a sample of blood from a patient, maintrac® can test the drug with the greatest likelihood of being effective on circulating tumor cells before treatment even starts. In addition, maintrac® can be beneficial in the metastatic stage for monitoring of treatment progress.
The maintrac® cell count progression in the metastatic situation should be assessed individually due to the many different interpretation possibilities. That’s why it is important that each patient is considered on an individual basis, with critical changes being investigated with further diagnostic tests.
Response of circulating tumor cells during the metastatic situation
The first measured value of the maintrac® cell count is always used as a basis value, which has little significance when considered alone. Only the cell count progression, which can be seen after further measurements are taken, can be interpreted.
Decreasing cell counts
The therapy should be effective when the number of cells decreases and the metastases shrink at the same time.
Depending on the circumstances, the circulating tumor cells may respond to a substance (reduction in cell count), but the metastases do not become smaller, or even grow (as the substance does not reach sufficient concentrations within the tumors).
If the cell count drops suddenly shortly after treatment, or without any treatment at all, this may be an indication that the circulating cells are accumulating somewhere in the body (self-seeding). Closer examination by the treating physician is absolutely necessary in these cases. In cases of metastasis formation, a drastic increase in the cell count after a previous low can be observed.
Constant cell counts
Whenever a metronomic therapy is administered, i.e. chemotherapeutic agents are given over a long-time period in very small but daily doses, then the cell count may stabilize.
Increasing cell counts
An increase in the cell count may indicate tumor growth or spread of metastases. It is very likely that the therapy has not been effective, and should therefore be modified after the testing of medications.
However, even if the tumor is destroyed by the drugs administered, cells may be released into the bloodstream. If a reduction in the size of the metastases can be identified at the same time as an increase in the number of circulating tumor cells in the blood, then the therapy should be continued until the cell count is reduced again in order to prevent the formation of new metastases.
A special case: No evidence of epithelial cells
In rare cases, no circulating tumor cells can be found in the blood of patients in the metastatic stage of the disease. The tumor cells can become structurally modified due to the many cycles of cell division which can result in the loss of surface antigens. This so-called de-differentiation can be the reason for circulating tumor cells becoming undetectable by epithelial-specific antibodies.