Cancer cells are masters at hiding. Sometimes they can spread to other tissues or organs at an early stage and remain undetected there for a long time. But why is cancer so difficult for the immune system to detect and why does cancer often come back after successful therapy?
The body’s defense system performs at its best every day. It fights invaders, repairs damage and disposes of diseased and dead cells. In relation to cancer cells, the immune system faces a particularly difficult task. Because cancer cells are the body’s own living cells – and the defense system is not designed to fight its own body. In addition, the so-called programmed cell death mechanism is often disabled in cancer cells. Normally, diseased cells kill themselves.
Cancer cells can make themselves invisible
In addition, malignant cells have a variety of different strategies to hide from the immune system. Cancer cells can make themselves virtually invisible. In addition, cancer cells inhibit immune responses, making them more difficult to attack.
So-called tumor stem cells are a particular problem. These have the ability to divide infinitely and form new cells over and over again. Thus, a single cancer stem cell can, in principle, produce a complete tumor. Fighting tumor stem cells with cancer therapies is difficult. Cancer stem cells have good repair mechanisms and even have the ability to eliminate cell toxins, such as those used in the course of chemotherapy.
Why cancer often comes back
It can happen that chemotherapy or radiation therapy successfully fights the tumor, but a cancer stem cell survives. This can be dormant for a long time, sometimes for years, and then at some point suddenly become active again. The cancer comes back. This is why, in most cases, recurrent cancer is a relapse, a flare-up of the same type of cancer. In addition, it can happen that a new cancer is due to the previous cancer therapy. In these cases, experts refer to it as a "second cancer".
To fight cancer, treatment often combines a variety of therapies. This increases the chance of reaching and killing as many cancer cells as possible. The challenge is to design the therapy in such a way that it is as aggressive as possible against the cancer, but causes as little damage to healthy cells as possible.
Every cancer therapy has its strengths
How the various therapy measures are combined varies from patient to patient. It depends, among other things, on the patient’s state of health, the type of cancer and the aggressiveness of the tumor. Surgery is mainly used for localized tumors. Systemic therapy that is effective throughout the body, such as chemotherapy, can be used before surgery, for example, to first shrink a tumor.
Both before and after surgery, chemotherapy can also launch a large-scale attack in the body against possible remaining cancer cells – even those that have already spread to more distant tissues. Radiation therapy is usually applied locally in order to treat the surrounding tissue, for example, in the case of breast cancer, the breast tissue and the lymph nodes located in the armpits.
Metastases: Even tiny tumors can sometimes spread
Usually not only the primary cancer is treated. If one does not know for sure whether the cancer has already spread, the therapy is often extended. Because not only larger tumors can form daughter tumors. In the case of black skin cancer, for example, it can happen that already tiny tumors form metastases that are small at first and therefore remain undetected.
It is even possible that a tumor discovered in the course of an examination is a daughter tumor and the primary tumor is hiding somewhere in the body. This is indicated by a tissue examination. If the tissue found does not match the location where it was found, doctors know that cancer is present elsewhere: For example, someone may have a bone tumor but it is made up of liver cancer cells because the cause (the primary cancer) is a tumor in the liver that has already spread to the bone.
Cure rates are good for many types of cancer
Even if the facts do not sound very optimistic so far: The chances of curing cancer are much better today than they were a few years ago. It is estimated that 50 percent of all cancer patients survive the cancer disease. Especially breast cancer and prostate cancer, which are common cancers, are usually well treatable.
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Of course, it would be even better if cancer could be prevented from developing in the first place. Colorectal cancer is an example here: Pre-cancerous lesions can be detected and removed during screening, so cancer often doesn’t develop in the first place.
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Important Notice: The information provided is in no way a substitute for professional advice or treatment by trained and accredited physicians. The contents of t-online can and may not be used to make independent diagnoses or to start treatment.