How is cancer cured

New therapies against cancer

Thanks to cancer research, we already know a lot about how cancer develops and how cancer cells differ in their behavior from healthy cells. These findings will help cure more people or make cancer more and more a chronic disease that you can live with longer than before. Nonetheless, many questions remain unanswered and it is by no means possible to treat every cancer successfully. The central goal of the Decade Against Cancer is to further strengthen cancer research and advance it in a targeted manner.

The current status

We now know that cancer begins with a single changed cell. What causes this cell to mutate is usually a highly complex interplay of various factors. For one, a predisposition to cancer can be inherited. On the other hand, there are certain behaviors and environmental influences that can cause the development of a tumor or reinforce a familial predisposition.

As part of cell renewal, new cells are created in our body every day. Sometimes errors occur and the cell experiences a change in its DNA (mutation). In most cases, the body repairs this itself or the immune system eliminates the mutated cell. Only if this does not succeed can it multiply - a tumor develops.

The “one fits all” approach no longer applies

For a long time, the affected organ played the most important role in the choice of treatment. There was one type of treatment for patients with breast cancer, for example, and another for those with lung cancer. However, it has been shown that people with apparently the same cancer diagnosis often respond differently to one and the same therapy.

In the meantime, in more and more types of cancer, it is the unique molecular changes in the tumor tissue of each individual patient that can be analyzed and specifically treated. The assumption that, for example, all breast cancer patients benefit from the same therapy has given way to the realization that there are different subgroups of the disease that require different treatment.

Personalized therapy on the rise

The long-term goal is to offer a perfectly tailored therapy for each patient based on the individual changes in the tumor: a tailor-made drug that is only produced for this one tumor and precisely attacks its weak point. For this, the genome of the tumor cells would have to beomics), the reversible changes in the genetic material (epigenomics), the changes in the messenger molecules for protein production (transcriptomics), the proteins in the cell (proteomics) and the metabolic products (English: metabolomics) can be analyzed in comparison with the healthy cells of each patient. The methods by which this is analyzed are summarized as omics“Technologies together.

The processing of the resulting large amounts of data is handled by medical informatics (more on the importance of medical data and their analysis in the digitization chapter). With their help, the essential information can be filtered out of the several gigabytes of data records. At the end there is a kind of Excel table from which the molecular characteristics of the tumor of the person concerned emerge. This table is used by the so-called Tumor Board, a committee of cancer experts that is used to interpret the results clinically and, on this basis, to select the best possible treatment for the person affected.

Division into smaller and smaller treatment groups

Based on the findings to date, it is already possible to narrow down patient groups for a whole series of types of cancer who can benefit from a particular treatment. Doctors call this "stratifying". For the division into these subgroups, the entire genome or the entire changes at the cellular level are not analyzed, but a targeted search is made in the blood or tissue of the person concerned for known characteristics for which treatment is already available today. Such characteristics are called biomarkers.

Personalized cancer medicine

Targeted Therapy

The targeted therapy, called “targeted therapies” in English, starts at the cellular level, for example suppressing signals that the cancer cell needs in order to multiply or it prevents the tumor cells from being supplied with oxygen and nutrients so that they are starved. Further starting points are the inhibition of metabolic activities in the cancer cells, which leads to their death or the inhibition of repair mechanisms. The targeted therapy has proven to be particularly effective in certain types of leukemia. They are also used for kidney, colon, lung and breast cancer as well as black skin cancer (malignant melanoma). Targeted active ingredients are usually used when the tumor disease is already advanced (metastasized) and can delay the progression of the disease for a while and alleviate the symptoms. As a rule, they do not lead to a cure.

Immunotherapy

The Immunotherapy enables the body's immune system to better recognize and fight cancer cells. This has an effect, for example, on some patients with black skin cancer or with certain types of lung or kidney cancer. In patients who respond well, immunotherapy can keep the disease under control for long periods of time. So far, a number of immunotherapies can only be used in the context of studies.

The immunotherapies include therapeutic vaccinations. On the one hand, antibodies with specific anti-tumor properties can be artificially produced in the laboratory and given to the patient in large quantities (so-called monoclonal antibodies). In Germany, monoclonal antibodies are already approved for the treatment of various types of cancer of the blood or tissue tumors. On the other hand, the patient's own immune cells can be modified outside the body in such a way that, after being reintroduced into the organism, they help the immune system to target the tumor (dendritic cells; CAR-T cells). The first CAR-T cell therapy methods for the treatment of patients with certain leukemias and lymphomas have been approved in Germany since 2018. Since many sufferers develop severe and sometimes life-threatening side effects, treatment is only carried out at specialized centers.

Another approach of immunotherapy is treatment with so-called Immune Checkpoint Inhibitors. Normally, the so-called checkpoints in the body have the task of controlling the immune system so that it does not attack the body's own, healthy cells. Some tumors influence these checkpoints for their own purposes and thereby prevent the immune system from recognizing and fighting the tumor cells. So-called checkpoint inhibitors counteract this. They release the brakes on the immune system and enable the immune system to take up the fight against cancer.

But tumor cells can find ways to evade treatment in the course of treatment - they become resistant. They then manage to use other intracellular processes to continue growing. In many cases, after another molecular analysis of the tumor cells, another drug can be used, which in turn attacks the new change in a targeted manner. Why tumor cells develop resistance to therapy is one of the great unsolved questions in cancer research and is also a concern of the Working Group of the Decade Against Cancer of the same name.

Professor Michael Baumann, Scientific Director of the German Cancer Research Center (DKFZ)

“If we discover cancer as early as possible, patients can be cured in many cases. To this end, we are developing and improving the range of imaging methods. In addition to anatomical information, they should also provide indications of the aggressiveness of the disease so that we can choose the appropriate therapy. There is also an urgent need for diagnostic biomarkers that show the risk of cancer or that we can use to track whether the cancer is responding to treatment. A lot of research is needed to do this. "