There are already vaccines, nanotechnology, gene and targeted therapy, personalized therapy - methods that give more and more hope to overcome cancer.
The report of the National Cancer Registry (February 2011) shows that the number ofcancercases in Poland has been growing rapidly for 30 years. The most common is lung cancer (21,000 cases a year), the second -breast cancer(10,000), and the next - colorectal cancer (5,500). Not all cases end in death. Increasingly, cancer is becoming a chronic disease that can be lived with for many years. This is due to new and more effective treatments.
What is happening now inoncology ?
» Prof. Janusz Siedlecki, chairman of the Scientific Council of the Oncology Center in Warsaw: For several hundred years, scientists have been studying the processes taking place in the normal cells of our body. Many of them have been decoded. Another goal is to understand the differences between the processes that take place in normal cells and those that take place in cells changed by the disease. Molecular medicine established in the 20th century deals with it. It tries to explain the course of the disease not only on the basis of the observed clinical symptoms, but also the molecular changes characteristic of diseased cells. In cancer, the idea is to link these changes to the type and course of the cancer.
What new did we learn about cancer development?
» J.S .: We are getting closer and closer to getting to know the different metabolic processes taking place in neoplastic and normal cells. First of all, it turned out that changes occur in neoplastic cells as a result of damage to the genetic material. This allowed us to establish that neoplastic diseases are the result of changes in many, sometimes very many, genes. Therefore, unlike monogenic diseases, commonly known as hereditary, neoplastic diseases are not hereditary. Only the tendency to get sick is inherited. Our body is equipped with mechanisms that eliminate cells in which many changes have occurred, i.e. cells prone to turn into cancer cells. One of these is the process of programmed cell death called apoptosis. Thanks to apoptosis, unnecessary cells, such as lymphocytes, which have been produced to fight infection, are removed from the body. AsI would like to add an interesting fact that during the day the body gets rid of about 10 grams of no longer useful (old or used) cells. In cancer cells, the mechanism of apoptosis is often defective as a result of changes in many genes. The immune system may also participate in the elimination of cells. However, for the immune system to work, a damaged cell must be distinguished from normal cells enough to be recognized as a foreign body, because only then can it be eliminated.
The most frequently used methods of cancer treatment so far consisted in removing altered cells …
» J.S .: Yes, traditional methods cancer treatments, such as surgery, chemotherapy, and radiation therapy, eliminate cancer cells. Surgery is the mechanical removal of the tumor. It is still the most effective method of treatment in cases where the disease is localized in one place. However, when it spreads throughout the body (i.e. when we are dealing with metastases) or when the primary lesion is extensive, we use chemotherapy or radiotherapy. Their goal is to damage cancer cells in such a way that the repair processes would not be able to restore their ability to divide. The use of these methods allows to cure, depending on the type of cancer, from 30 to even 100 percent. neoplastic diseases.
The percentage is a good result, but far from being fully satisfied. There are still cancers that we cannot control.
» J.S .: That's right. That is why we are constantly looking for more effective treatments. At the end of the last century, new possibilities emerged, which are based on discoveries of the course of metabolic processes in cancer cells.
How can we influence the biological processes taking place in damaged cells?
» J.S .: There are several ways. The first is that we 'teach' lymphocytes, or cells of the immune system, to recognize cancer cells and remove them from the body. This mechanism is the basis for the action of vaccines, which are gaining more and more importance in modern oncology. They are gradually introduced to the treatment of melanomas, kidney and lung cancer. The second trend is an attempt to restore damaged genes to their correct form, i.e. gene therapy. This method has had its ups and downs, but it's back. We have learned to introduce the correct genes into cancer cells by means of various carriers. They are to replace those that have been damaged. In gene therapy, the main problem is getting the correct gene out to all abnormal cells. By using this method,genes that inhibit, for example, the formation of blood vessels through which the tumor nourishes the tumor can be introduced into neoplastic cells. It is known that cancer only grows when it receives food and oxygen from the blood. The faster it grows, the more food and oxygen it needs. Depriving him of this possibility leads to a slower division of neoplastic cells, which means limiting the growth of the tumor. Currently, at the Institute, we are conducting research on gene therapy that inhibits the process of angiogenesis (it is the process of creating blood vessels on the basis of existing ones). There are also clinical trials with this type of therapy in vulvar cancer. The results of this research are promising.
Gene therapy can be used in other ways?
» J.S .: This is the so-called suicide therapy. Simply put, it's another form of gene therapy. Diseased cells are loaded with genes that are not found in our body. Their products, or proteins - usually enzymes - have the ability to convert a prodrug into a drug. Administration of a prodrug that is harmless to the body causes that it is converted into a cytostatic drug only in neoplastic cells. It is therefore a way to avoid the side effects that are so characteristic of chemotherapy with cytostatics.
And nanotechnology?
» J.S .: Currently, it is most often used to deliver drugs to cancer cells. For example, we can introduce a drug, e.g. a chemotherapeutic drug, inside nanoparticles made of a polymer that is biodegradable, i.e. it is decomposed in the body. We can also attach (coat) such a ball with an antibody or bacterial toxin. These nanospheres are introduced into the bloodstream. They travel with the blood until they reach the vessel that nourishes the tumor. Since this vascularization differs from normal, the nanospheres clog in such vessels. When the capsule degrades, the drug escapes and destroys the cancer cells.
High hopes for patients are also raised by targeted therapy.
» J.S .: Right, because it offers new possibilities. Targeted therapy is aimed at inhibiting abnormal metabolic processes that stimulate the division of neoplastic cells.
Why - unlike he althy cells - do neoplasms divide endlessly?
» J.S .: In order for a cell to divide, it must receive a signal that there is a place to divide and that its genetic material is not damaged. Cancer cells have very damaged genetic material. This is the main reason why their mechanisms regulating division stop working in them.We say that cancer cells become immortal. By affecting the signal pathways to be divided, we can inhibit the ability to divide excessively. In other words, we can stop tumor growth.
How do you know which method to use to destroy the cancer?
» J.S .: We can make the right decision, because we know a lot about the biology of cancer. The beginning of targeted therapy was the use of hormone therapy in the 1960s. Today, more sophisticated methods are used. As I have already mentioned, a cancer cell is constantly changing its genetic material. In order to avoid lethal changes, i.e. changes that result in cell death, the genetic material must be constantly repaired. We have 7 main repair systems and 14 auxiliary systems in each cell. Without their work, our species would cease to exist. Therefore, if we apply a factor that inhibits DNA repair processes to a cell, degenerative changes occur in it so large that the process of programmed cell death is triggered and the cell dies. Another way is to inhibit signals to divide. The signal is usually transmitted by the so-called growth receptors. Signal transduction is when one protein - called a ligand - attaches to another - called a receptor. This combination leads to the appearance of enzymatic activity in the complex thus formed, which activates other proteins responsible for further signal transduction. Therefore, as part of targeted therapy, drugs are administered that block the flow of information to proteins that control the processes of repair, growth and division of diseased cells. Currently, targeted therapy is successfully used to treat cancers of the lung, breast, kidney, liver, gastrointestinal stromal tumors, and lymphomas.
Targeted therapy also has fewer side effects.
» J.S .: Indeed it is less burdensome. But it must be remembered that not every patient - due to the individual course and the biology of the tumor - can be used. In order for it to bring the expected results, additional diagnostic tests are necessary. Let me give you an example. Some cancer cells, such as breast cancer, have many molecules of a specific type of receptor - HER2, on their surface. If we detect the presence of this receptor, appropriate therapy can be given. The problem, however, is that only about 20 percent. patients have an excess of breast cancer cells - we call it overexpression - HER2. If this group of patients is given a drug (herceptin), they will significantly benefit from this treatment. There is no point in using the drug in people who do not have these types of receptors, because the treatment will not be effective.
More and more often she saysabout the need to personalize your treatment. What does it mean?
» J.S .: Personalized cancer therapy is not a new idea. We have been developing its principles for 20 years. In other words, it is a treatment tailored to a specific patient - tailored. The immune system works differently for each patient, the neoplasm has a different biology, and the metabolic disorders in the cells are different. Therefore, through detailed diagnostic tests, we try to get to know these processes and choose the treatment in such a way that the patient gets the most benefits from it.