Residual disease (or minimal residual disease MRD) is, to put it simply, everything that remains in the body after cancer treatment in the first stage. Most cancers are removed with surgery, chemotherapy or radiotherapy. It happens that in the body there are so-called "Leftovers" (e.g. in the bone marrow or lymph nodes) that over time may lead to a recurrence of the disease.
Detection ofresidual diseaseis one of the most important prognostic indicators in assessing the course of treatment and the risk of disease recurrence in acuteleukemias . Regular bone marrow checks allow for earlier detection of disease recurrence. In detectingMRDthe so-called flow cytometry. This technique enables the description of the population of cells on the basis of e.g. their size or granularity and the determination of their expression level, based on the intensity of fluorescence.
Classic diagnostic methods (e.g. under a microscope) do not give a complete picture of MRD. In the case of leukemia, the situation is particularly difficult, because cells similar to those that cause residual disease are also found in he althy bone marrow. I am talking about the so-called precursor cells from which various types of blood cells are formed at a later stage. In he althy bone marrow, precursor cells are found in small numbers. However, if such a cell is affected by an unfavorable impulse, it can become malignant, giving rise to leukemia.
Minimal residual disease - threats
When malignant cells begin to divide, they overgrow. They begin to multiply and take space from he althy blood cells. If there are more than 25 percent of them. of all cells, one can speak of leukemia. This number should be reduced to less than 5 percent as soon as possible. However, it is still not known whether among these 5 percent. only he althy cells will remain, or also leukemia cells. It is at this stage that you can speak of a residual disease.
Minimal residual disease - prophylaxis
In MRD it is very important to monitor the disease - to do this, the marrow is taken, kept in a liquid state, non-dangerous cells are centrifuged, and the rest are tested. Residual disease monitoringintroduced into clinical practice in many Western countries, such as Germany, the Netherlands or Italy (in Poland this study is still too expensive). Based on their results, decisions about further treatment are made.
Minimal residual disease - treatment
In order to remove MRD, the remission consolidation stage is used in treatment after the remission induction step. It involves the use of cytostatic drugs in high doses. It is important in this phase to protect the patient well against complications.