[Fat Bear Science] Will you produce "antibodies" after having cancer?

Fat Bear, do you think people who unfortunately suffer from cancer will get it again in the future?

What do you think?

I don't think so. For example, chickenpox, measles, and smallpox, which have been eradicated, are examples of diseases that only occur once in a person's lifetime. Once someone has had one, they will develop antibodies in their body and will not get it a second time.

The example you gave makes sense, but it doesn't apply to cancer. People who have had cancer still have a chance of getting cancer again. Let Dr. Fat Bear tell you about it!

In recent years, with the advancement of medicine and the concept of early diagnosis and early treatment, cancer is no longer a terminal illness. The most popular anti-cancer treatment is also a variety of "immunotherapy". So, since cancer cells are foreign bodies in the body, will cancer stimulate itself to produce antibodies, thereby playing a key role in the anti-cancer process? Can all cancers be completely eliminated through vaccines or immunotherapy?

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Wang Donglin

Head of the Department of Oncology at the Affiliated Cancer Hospital of Chongqing University, chief expert on colorectal cancer. Chief physician, professor, doctor of medicine, and doctoral supervisor.

He is good at chemotherapy of malignant tumors and molecular targeted therapy of tumors, especially in the diagnosis and treatment of malignant tumors such as colorectal cancer, lung cancer, and gastric cancer.

Clinic hours: Monday morning, Thursday morning

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Lei Shuangyi

Member of the Chinese Anti-Cancer Association, Master of Oncology from Chongqing Medical University, and resident physician in the Department of Oncology at the Affiliated Cancer Hospital of Chongqing University.

He is mainly engaged in the comprehensive internal medicine treatment of malignant tumors and is currently conducting preliminary research on tumors of unknown primary focus.

Why does the human body produce antibodies?

During the long process of evolution, the human body has formed a complete defense network - the immune system.

Non-self substances, senescent cells and certain components of cancerous cells from outside the body will be recognized by the immune system in the body. These substances are called antigens. Antigens will stimulate the immune system to produce corresponding antibodies. Antibodies and antigens will be precisely combined (like a key fitting a lock), thereby activating the body's immune system. The activated immune cells will eliminate these non-self substances, senescent cells and most cancerous cells.

Immune cells are like loyal guards, always protecting our health. For example, the COVID-19 pandemic is caused by the new coronavirus, which is a non-self substance outside the body and contains some antigens that can be recognized by the human body. Researchers can use these antigens to prepare vaccines. After the vaccine is injected, protective antibodies will be produced in the body, thus playing a protective role in advance.

Cancer cells can evade the immune system

Monitoring and Attacks

So the key is: whether you can produce antibodies after having cancer depends on whether the cancer cells contain antigens that can be recognized by the immune system.

Unfortunately, cancer cells originate from the body's own cells, and most of their components are similar to normal cells. Although cancer cells also express some new antigens on their surface that normal cells do not have, and most of them can be recognized and killed by the immune system, a few "cunning" cancer cells will constantly modify their own antigens or change the environment around the cells to evade the immune system's monitoring and attack, causing the immune system to lose control of the growth of cancer cells, just like criminals constantly changing their appearance and falsifying identity information in order to avoid arrest by the police. This is the immune escape mechanism of tumors.

Therefore, even if you have had cancer, due to the immune escape mechanism of cancer cells, even if the body produces corresponding antibodies, it is not enough to cope with the "crazy growth" of the tumor. And the original antibodies can only match the primary tumor and cannot prevent the body from getting cancer again.

If you don't understand, ask

Some people may ask: If the immune escape mechanism helps tumors grow, then can the currently popular HPV vaccine help prevent cervical cancer?

In fact, the cervical cancer vaccine is not aimed at cancer cells, but at the virus that causes cervical cancer - HPV. Data shows that 99.7% of cervical cancer patients can detect HPV infection, of which the most common high-risk types are HPV16 and HPV18. More than 90% of cervical cancer in China is related to persistent infection with these two high-risk HPV types. However, human immunity to HPV is generally not strong, and it cannot produce a large number of antibodies in time to respond like the common cold, which leads to the long-term survival of HPV and causes cervical cancer.

The HPV vaccine injects particles with HPV antigen characteristics into the human body to induce the immune system to recognize them and produce antibodies, thereby eliminating the virus and reducing the incidence of cervical cancer. It does not allow the body to directly produce antibodies to eliminate cancer cells.

How to “plug” the “loophole” through which cancer cells escape?

Now that we have made it clear how cancer cells escape the human immune system, let’s talk about how to plug this “loophole”.

Immunotherapy

Blocking the pathways through which cancer cells escape

The principle of immunotherapy is more complicated than that of HPV vaccine. It is a method of controlling and eliminating tumors by restoring the body's normal immune response to cancer cells through drugs. For example, the PD-1/PD-L1 inhibitor is the most widely studied in medicine.

Research has found that cancer cells can produce a protein called PD-L1, and there is a protein called PD-1 on the surface of immune cells, which is like a key and a lock. These two proteins can bind to each other, but this combination does not allow immune cells to eliminate cancer cells. After they bind, the killing function of immune cells will be suppressed. It is equivalent to covering the immune system with a thick veil, turning a blind eye to cancer cells that pass by, allowing cancer cells to successfully escape immunity.

After the immune drugs are injected into the body, they can accurately bind to the proteins on the surface of cancer cells. In this way, the proteins on the surface of cancer cells and immune cells will not bind to each other, the killing function of immune cells will not be suppressed, and the immune system will be able to work normally. At this time, the body can achieve anti-cancer effects by producing antibodies.

Theoretically, if you have cancer and produce antibodies, you can use immunotherapy drugs to help you achieve this. But in reality, based on current research progress, the percentage of people who are actually cured through immunotherapy is not high. This also proves that the immune escape methods of cancer cells are far more complicated than imagined, and more research is needed to uncover the secrets.

Targeted therapy

Synthesizing antibodies that destroy cancer cells

Since the human body lacks the ability to produce large quantities of anti-cancer antibodies, if we develop special antibodies with anti-cancer properties, is it possible to kill tumors by injecting antibodies?

The answer is yes. This type of antibody is synthesized by researchers to destroy cancer cells. After entering the body, it can accurately bind to cancer cells to achieve the purpose of killing cancer cells. For example, rituximab for the treatment of non-Hodgkin's lymphoma, trastuzumab for the treatment of breast cancer, and cetuximab for the treatment of colorectal cancer have been widely used in clinical practice. However, the mechanism by which they work is different from that of immune drugs. It mainly binds to certain proteins on the surface of cancer cells, directly causing cancer cell apoptosis, similar to the precision strike of missiles and the target hit by archery, and does not rely on the immune system. However, this type of protein also exists in normal human cells, so some side effects will occur after use, such as fever, rash, etc., but under strict dosage control, these side effects are often controllable.

Immune cell therapy

Engineering and breeding immune cells that recognize cancer cells

In addition, since the proportion of autoimmune cells that can recognize cancer cells is very small (note: one in 100,000), researchers try to extract immune cells from the patient's blood, and through special modification, enable them to recognize antigens on the surface of cancer cells, and then amplify these modified cells on a large scale, and finally return billions of modified immune cells to the human body. While the immune cells are functioning, they will continue to reproduce themselves, thereby achieving the goal of long-term and precise tumor killing. This is the cell therapy that has achieved initial results.

Immune system modulators

Activate the immune system to fight tumors

Sometimes we see in the news that BCG is used to treat bladder cancer, and thymopentin is used to inhibit cancer. These drugs also activate the immune system to achieve anti-tumor effects, and are called immune system regulators. However, the anti-cancer effect of immune system regulators alone is very weak, and you still need to go to a specialist hospital to listen to the opinions of specialists and receive comprehensive and systematic anti-cancer treatment.

Cancer is a systemic disease

Regular follow-up is very important

After having cancer, it is more important to follow up after treatment than to worry about whether antibodies are produced.

Although some patients can achieve clinical cure after surgery or multiple treatment methods, cancer is a chronic, complex systemic disease, and some patients will still experience recurrence or even metastasis after treatment; or some patients are already in the middle or late stages when the tumor is discovered. Even if the treatment is effective, the remaining cancer cells in the body will re-proliferate when treatment is stopped or the body's immunity decreases.

For clinically cured cancer patients, medicine usually uses 5 years as the boundary. If there is no recurrence or metastasis within 5 years, the possibility of recurrence or metastasis after 5 years will be greatly reduced (Note: it is not 100% against recurrence or metastasis).

Regular follow-up is very important. First, it can help cancer patients detect and treat cancer early again, so as not to miss the best treatment opportunity. Second, it can help provide psychological support and comfort to patients. Third, it can timely adjust medication, examination and other treatment plans. The time and content of follow-up vary depending on the type of cancer. Specific influencing factors include cancer stage, tumor malignancy, whether surgery is performed, lymph node metastasis, metastasis to other parts, and treatment course.

In principle, most cancer patients need to be reexamined every three months within one year after treatment, and those who have been treated for more than five years need to be reexamined every six months to one year. Within 2-4 years after treatment, they need to consult an oncologist based on their own conditions and develop a reasonable follow-up plan based on their own condition and the doctor's experience. The follow-up of patients with advanced cancer is mainly to understand the development of the disease and guide subsequent treatment. A specific follow-up plan needs to be developed based on the condition.

Regardless of whether it is in the early or late stages, if there are changes in health status, you should return to the hospital as soon as possible and report to the doctor in a timely manner. Allowing the doctor to determine whether these problems are related to cancer and to intervene in a timely manner is the key to prolonging survival and ultimately "curing".