Cure for cancer: What comes to replace chemotherapy
Recently it BECAME KNOWN THAT the NOBEL PRIZE was awarded to two scientists who made the discovery, which led to a revolution in the treatment of cancer. The development of new types of therapy takes decades, and the complex terminology is not always clear to the General public — and in the air hung the question whether they found an effective cure for cancer. We understand why one medicine for all types of tumors can not be and how far from traditional chemotherapy Oncology has advanced now.
Why cancer is not one disease
Malignant tumors can develop from a variety of cells — from skin epithelium to muscle, bone or nervous system cells — and occur in a variety of places in the body. Basic knowledge of where the tumor originated and what it consists of allowed doctors to plan operations better — but it was unclear why in some cases the cancer leads to rapid death, in others it is effectively cured, and in others it seems to disappear, but in a few years it can return with new strength.
Now the molecular mechanisms of tumor development are being studied more deeply — and it is already clear that they can not be classified only by localization, stage and tissue. If earlier breast cancer was considered one disease, it is now clear that it can be different — and what receptors are on the tumor cells, depend on the possibility of treatment and the likely outcome. The study of how cancer develops, far from its completion — it seems that here as nowhere works the principle of “the more we know, the more we do not know.” In addition, advanced, metastatic tumors remain a special problem — they are much more difficult to treat than those found in the early stages. But in the treatment of some types of cancer revolution still occurred.
What is the problem with chemotherapy and radiation therapy
Chemotherapy-is the introduction of cytotoxic (ie toxic to cells) substances, most drugs are administered intravenously. They are designed to destroy rapidly dividing cells – and in addition to tumor cells “gets” and other tissues, where they multiply rapidly. This is the skin, mucous membranes and bone marrow in which blood cells are formed — so typical side effects of chemotherapy include hair loss, stomatitis, intestinal problems, anemia.
In radiation therapy, the area where the tumor is located (or where it was before, if it was removed surgically) is subjected to powerful radiation. Such treatment can be carried out before the operation to reduce the volume of the tumor (then it will be easier to remove), or after the operation in an attempt to destroy all the remaining malignant cells. The main problems of radiation therapy are the same as in “chemistry”: firstly, even with the use of modern devices and techniques it is impossible to completely protect healthy tissues from aggressive effects, and secondly, cancer mortality remains very high.
What is treated with hormone therapy
Hormone therapy of cancer was mentioned by Solzhenitsyn in the book “Cancer corps“, where it was said that for the treatment of certain tumors, female or male hormones are administered. Tumors, the growth of which depends on the influence of hormones, do exist — and for the best effect it is important to eliminate this effect. However, it does not use hormones and their antagonists — the means that inhibit the synthesis of certain hormones or change the sensitivity of receptors to these hormones in the cells.
This therapy is actively used for breast cancer in postmenopausal women or, for example, prostate cancer in men. Breast cancer cells are often sensitive to hormones, that is, they contain receptors that recognize estrogen, progesterone or both of these hormones. The presence of such receptors can be detected during a special analysis — and then prescribe drugs that will block the receptors, not allowing hormones to stimulate the re-growth of the tumor.
When stem cells really work
About stem cells are often spoken either in the context of questionable rejuvenation procedures (we have already told why the creams add stem cells of plants), or in the framework of scientific achievements with loud headlines like “scientists have grown teeth from stem cells”, but, unfortunately, is low practical value. But in malignant tumors of the bone marrow and blood stem cells just quite successfully used.
In some types of leukemia and multiple myeloma, stem cell transplantation is an important component of treatment. High doses of chemotherapy destroy not only malignant blood cells, but also normal cells and their predecessors — which means that the blood will simply be deprived of cells and will not be able to perform its tasks. Therefore, after chemotherapy, transplantation is performed — the patient is injected with his own (obtained in advance) or donor stem cells. Of course, this method is not without problems — it is hard to tolerate and is not suitable for all patients. Given that the same multiple myeloma is considered a disease of the elderly (usually it occurs after 65-70 years), for many patients the possibility of treatment is very limited.
What is targeted therapy
The further the cancer science develops, the more opportunities there are to influence drugs on a certain target (target in English) — and not on the whole body, as it happens with chemotherapy. Some tumors are characterized by mutations of specific, already known, genes, leading, for example, to the production of large amounts of some abnormal protein-and this helps the tumor to grow and spread. For example, if lung cancer is detected mutation of the EGFR gene and produces a lot of protein with the same name, the tumor can be fought not only classical methods like chemotherapy, but also inhibitors of EGFR.
Now there are drugs that were active when mutations of different genes characteristic of certain types of cancer. Patients are tested for these mutations to determine whether it makes sense to use such therapy: it is expensive and gives a good effect when the body has a target for it, but is useless if there is no target. The targeted drugs include drugs that block angiogenesis, that is, the formation of new blood vessels that feed the tumor. Hormonal and immunotherapeutic agents can theoretically also be attributed to the target-they are exactly what affects certain targets, but for practical convenience they are usually taken out in separate groups.
For which they gave the Nobel prize
Immunity is a powerful and complex system that not only helps to heal wounds or fight colds. Every day there are mutations that can cause the cell to divide uncontrollably and become malignant; the immune system destroys such defective cells, protecting us from cancer. At some point, the balance may be disturbed, and this is not the fault of “reduced immunity“, and special mechanisms by which tumor cells “escape” from the immune response. The discovery of these mechanisms was the reason for the Nobel prize of James Ellison and Tasuku Honjo — it formed the basis of immunotherapy, a new approach to cancer treatment.
The essence of immunotherapy is to make the immune system attack and destroy malignant cells on its own. Several drugs from this group are already registered in different countries, and many more are in development. Allison and Honjo discovered immune control points, molecules that were used by cancer cells to suppress the immune response. There were drugs that suppress these molecules (they are called inhibitors of immune control points) — and in Oncology there was a revolution. For example, with melanoma (a disease with 100% mortality previously), some patients managed to eliminate all signs of the disease-and these people are alive for ten years.
Some of these drugs act on the mechanisms characteristic of a variety of malignant processes. For example, pembrolizumab is registered for the treatment of many tumors, provided that they have a certain molecular feature associated with a violation of DNA repair and increased susceptibility to mutations. Other drugs are used in one or two types of cancer-it all depends on the molecular target, which can be affected by drug antibodies. Finally, the most complex immunotherapeutic method is CAR — T, in which human immune cells are “trained” to attack the tumor. The method is already registered for the treatment of acute leukemia in children, because of its complexity and novelty, the cost of treatment of one person can reach half a million dollars.