Medicine

Chemotherapy – what is it?

Most of us think chemotherapy is simply a way to fight cancer. However, the topic is actually much broader and more complex. Regardless of whether you are diagnosed with cancer, or if you have someone close to you who has been diagnosed with it, you should learn as much as possible about it before starting chemotherapy. Knowledge about the specificity of treatment is one of the elements necessary to deal with difficulties that may arise during its course. So what is chemotherapy really all about?

How do chemotherapy drugs work?

In order to properly understand the effects of chemotherapy drugs, it is important to understand the life cycle of a human cell. The complete cell cycle consists of the following phases:

G1 – the phase of cell preparation for DNA synthesis and division;
S – the phase of DNA synthesis in which the number of chromosomes is doubled;
G2 – second phase of growth and preparation for cell replication;
M – mitosis, i.e. the phase in which the division into two cells takes place.

Cells resulting from mitosis can continue to divide, and when they start to age, they enter the G0 phase, i.e. the resting phase, the alternative of which is apoptase – self-destruction of the cell.

The development of neoplastic changes is initiated as a result of damage to a gene in the DNA of a healthy cell. This can be caused by many factors, such as congenital mutations, chemical factors or viral infection. As a result of the damage, a single mutation is formed that affects the further development of the cell. If it is not repaired, or if the cell does not die, the genetic changes will continue to progress until the mutant cell eventually becomes cancerous.

A characteristic feature of these cells is the ability to multiply very quickly and in an uncontrolled way. As a result of the intensive division and replication of neoplastic cells, a neoplastic tumor is formed, the further growth of which may disturb the functioning of organs and cause metastasis to other parts of the body. The entire process may be asymptomatic for up to several years.

Cytostatic drugs administered during chemotherapy are profiled to be toxic to rapidly dividing cancer cells. Their task is to inhibit mitosis (division) of neoplastic cells, which they usually accomplish by damaging DNA and structures responsible for the process of cell division. Rapidly dividing cells also occur naturally in a healthy human body (including skin and hair cells), which is why many patients undergoing chemotherapy experience side effects.

For information on how to prepare for chemotherapy, see the article: What do you need to know before starting chemotherapy?

When is chemotherapy used?

There are many strategies for administering cytostatic drugs – they can be introduced before or after tumor removal surgery and as the only or one of several ways to fight cancer. There are many variants, and the choice of the right one depends on the nature of the neoplastic changes - the stage of development, size and location. One method is to use chemotherapy in parallel with other methods, such as radiotherapy or hormone therapy. Another way is combination (complex) chemotherapy, which consists in the simultaneous use of different cytostatic drugs. Chemotherapy is also often introduced to treat a patient before engaging in other cancer treatments, and it’s called neoadjuvant method. It is usually used for large tumors that cannot be removed surgically. In such situations, preoperative chemotherapy helps to reduce its size and thus gives a chance for surgery. As for adjuvant chemotherapy, it is used after initial treatment, e.g. after surgery in cases where there is a high risk of disease recurrence and metastasis. Chemotherapy is also used to maintain a state of remission (when the symptoms of cancer have disappeared).

How is chemotherapy performed?

Chemotherapy is a systemic treatment, which means that the whole body is included in the treatment. Its course depends mainly on the cancer strategy chosen by the doctor. The choice is influenced by many factors, so it is very important to know the specifics of the tumor on which the response to chemotherapy depends. The very treatment with cytostatic drugs takes place in the so-called cycles. This term is used to describe the sequence of drugs administered over 2-4 weeks. Usually, the treatment is administered in 3-5 cycles, and in cases where it is required, it may even include several cycles. Depending on how the body responds to treatment, the established course of action may be modified. This happens when chemotherapy does not work - for example, when the cancer is still growing. In such a situation, drugs are changed to other drugs.

How are drugs administered during chemotherapy?

There are several methods of administering chemotherapy, and the selection of the appropriate one depends on the nature of the cancer that will be subjected to it:

Intravenous chemotherapy. It is the most common method of drug administration. It is usually done in a hospital setting through a drip. An alternative method that allows you to avoid multiple punctures with a needle are the so-called intravenous ports.
Oral chemotherapy. In this method, the drugs are administered in the form of tablets, which the patient takes as directed by the doctor. The number of drugs that can be administered in this way is limited.
Intrathecal chemotherapy. This method consists in administering drugs through a catheter or puncture needle directly into the cerebrospinal fluid and thanks to its use, their higher concentration is obtained.
Intraperitoneal chemotherapy. It is a method in which cytostatic drugs are administered into the peritoneal cavity, thanks to which it is possible to obtain their higher concentration, and thus a stronger effect on the tumor located in this area.

What are the side effects of chemotherapy?

Chemotherapy drugs are designed to eliminate rapidly dividing cancer cells. However, these types of cells are also found in a perfectly healthy body – the cells that make up the tissues that make up the skin, hair, and intestines. As a result, some of them are also destroyed, which is associated with the patient's side effects, such as hair loss or nausea. Many patients also experience fatigue, and most are at risk of infection and the development of anemia. However, there are many ways to help reduce their annoyance. Proper supplementation and constant contact with the doctor play a very important role in this matter.