Chemotherapy: what it is, how it works, and when it is prescribed

The treatment of cancer is one of the most pressing issues in modern medicine. For many cancer patients, chemotherapy is the main method of fighting the disease. This method of cancer treatment raises many questions and concerns among patients. In this article, we will discuss what chemotherapy treatment is, how it affects the body, and what to expect during and after therapy.

What is chemotherapy?

Chemotherapy is a method of drug treatment for malignant tumors using drugs that inhibit the growth and division of cancer cells or destroy them completely.

Malignant cells divide much faster than healthy cells and are therefore more vulnerable to the effects of these drugs. Chemotherapy is used both as a standalone treatment and in combination with other methods, such as surgery, radiation therapy, or immunotherapy.

How does chemotherapy affect the body?

Chemotherapy drugs circulate in the bloodstream throughout the body and affect cancer cells regardless of their location.

However, the drugs affect not only malignant cells, but also healthy cells throughout the body. This explains most of the side effects of therapy.

The effect on the bone marrow can lead to a decrease in the level of leukocytes, erythrocytes, and thrombocytes. Damage to the mucous membranes manifests itself as mucositis, nausea, vomiting, and diarrhea. Peripheral neuropathy is possible on the part of the nervous system.

How does chemotherapy affect the tumor?

The mechanisms of the antitumor action of chemotherapy drugs depend on the class of drugs.

• Alkylating agents damage the DNA of cancer cells, preventing their replication.
• Antimetabolites are incorporated into the metabolic pathways of the cell instead of normal metabolites, blocking DNA and RNA synthesis.
• Anthracycline antibiotics cause DNA chain breaks.
• Platinum derivatives form cross-links in DNA, blocking its replication and transcription.

Some tumors, such as lymphomas, leukemias, and germ cell tumors, respond well to this treatment. Other types of cancer, such as melanoma or kidney cancer, are more resistant to standard chemotherapy.

Degrees of chemotherapy toxicity

The international CTCAE (Common Terminology Criteria for Adverse Events) system evaluates side effects on a five-point scale, where 0 means no toxicity and 5 means very high toxicity.

At level 1, side effects are mild and no medical intervention is necessary. At level 2, moderate symptoms are possible. At grade 3, symptoms are pronounced, and hospitalization or a change in treatment regimen is necessary. Grade 4 can cause a life-threatening condition. Emergency medical care is required.

Monitoring side effects helps the doctor to adjust drug doses in a timely manner or suspend treatment to restore bodily functions.

Types of chemotherapy

Types of therapy are classified according to various principles.

By mechanism of action:

• alkylating agents
• antimetabolites
• antitumor antibiotics
• topoisomerase inhibitors
• mitotic inhibitors
• platinum derivatives

By method of administration:

• intravenous
• oral
• intramuscular
• intrathecal
• intraperitoneal
• intravesical

According to the color classification, it is worth paying attention to the so-called red chemotherapy. It includes anthracycline drugs. They have a characteristic red color and are considered to be among the most toxic.

Blue chemotherapy - mitoxantrone and mitomycin, also has pronounced toxicity.

White chemotherapy or yellow is less aggressive. This group includes taxanes, platinum drugs, and some cytostatics.

Adjuvant chemotherapy

Adjuvant chemotherapy is prescribed after surgical removal of the tumor. Its purpose is to destroy any remaining cancer cells and reduce the risk of recurrence.

Chemotherapy after surgery is especially important when there is a high risk of recurrence. Adjuvant therapy has been shown to prolong recurrence-free survival in many types of cancer, including breast, colon, stomach, and lung cancer.

Neoadjuvant chemotherapy

Neoadjuvant chemotherapy is administered before the main treatment, most often before surgery. The main goal of this approach is to reduce the size of the tumor.

Additional benefits of neoadjuvant therapy:

• the ability to assess the sensitivity of the tumor to specific drugs
• early initiation of systemic treatment to control possible micrometastases
• improved local control of the disease.

Palliative chemotherapy

Palliative chemotherapy is used in cases where a cure is not possible, but it is necessary to control the course of the disease and improve the patient's quality of life. Palliative treatment aims to reduce symptoms, slow the progression of the disease, and ensure the most comfortable life possible.

Less aggressive regimens are used in this type of therapy, and the intervals between courses may be extended.

Targeted chemotherapy

Targeted chemotherapy involves the use of drugs that specifically target specific molecular targets in cancer cells. Unlike traditional cytostatic therapy, which damages all rapidly dividing cells, targeted drugs block specific signaling pathways or proteins necessary for tumor growth and survival.

Targeted drugs include monoclonal antibodies, tyrosine kinase inhibitors, angiogenesis inhibitors, and other classes of drugs.

Radiation chemotherapy

Radiation chemotherapy or chemoradiation therapy is a combined method in which chemotherapy and radiation therapy are used simultaneously or sequentially. However, it is important to consider the limitations and contraindications for the latter.

Chemoradiation therapy is widely used for cancer of the esophagus, rectum, cervix, head and neck, as well as non-small cell lung cancer. Despite its increased effectiveness, this approach has a more negative effect on the mucous membranes in the area of irradiation.

Tablet chemotherapy

Tablet chemotherapy is convenient for the doctor to administer, and the patient can be treated on an outpatient basis.

Advantages of the tablet form: no need for regular visits to the clinic for intravenous infusions, reduced risk of catheter-associated complications. However, adhere to the exact regimen for taking the drugs and promptly report any side effects to your doctor.

Chemotherapy effects

The effects of treatment can be short-term, occurring during or immediately after treatment, and long-term, occurring months or years later. After chemotherapy, side effects may include:

• hematological toxicity: decreased white blood cell, red blood cell, and platelet counts
• gastrointestinal side effects: nausea, vomiting, diarrhea, constipation, loss of appetite, and mucositis
• alopecia (hair loss)
• peripheral neuropathy with numbness, tingling, or pain in the extremities
• Pain after chemotherapy can have various origins: neuropathic pain due to nerve damage, myalgia and arthralgia, possible pain at the site of metastases, or headache
• heart failure

Long-term effects: fertility problems, early menopause, secondary malignant neoplasms, chronic fatigue, cognitive impairment, pulmonary fibrosis, cardiomyopathy.

How is chemotherapy administered?

How does chemotherapy work? It depends on the type of drugs, the stage of the disease and the general condition of the patient. Before starting treatment, the doctor will conduct a comprehensive examination: prescribe laboratory blood tests, biochemical parameters of liver and kidney function, cardiac examination and instrumental imaging methods.

Intravenous chemotherapy is performed through a peripheral venous access or a central venous catheter. For long-term courses, port systems or PICC catheters are often installed. They provide reliable venous access and reduce the risk of drug extravasation. The duration of the infusion varies from several minutes to several hours, depending on the medication.

How long does chemotherapy last?

How long does a course of chemotherapy last? This is determined by the treatment protocol. A course of chemotherapy usually consists of one or more cycles.

The duration of one cycle is from 1 to 4 weeks. The total number of cycles ranges from 4 to 8. For example, for breast cancer, the standard course of adjuvant chemotherapy is 4-6 cycles, each lasting 21 days. In total, this is 3-4 months. For some hematological malignancies, treatment can last a year or more.

Palliative chemotherapy is often performed before the disease progresses or unacceptable toxicity appears, so its duration may be significantly longer. The treatment schedule is adjusted depending on the tolerability of the therapy and the dynamics of the disease.

Rehabilitation after chemotherapy

The goal of rehabilitation is to restore physical and psycho-emotional well-being, improve quality of life, and return to normal activity. Rehabilitation measures begin during active treatment and continue after its completion.

• Physical rehabilitation: moderate physical activity to help overcome chronic fatigue and restore muscle strength and endurance. Moderate aerobic exercise, yoga, and therapeutic gymnastics help improve overall well-being.
• Nutritional support: a dietitian helps develop a balanced diet that provides sufficient protein, calories, vitamins, and minerals.
• Psychological rehabilitation: work with a psycho-oncologist, group therapy. Professional psychological support helps to overcome anxiety, depression, and fear of recurrence.

What should you not do after chemotherapy?

First and foremost, avoid any sources of infection: contact with sick people, visiting crowded places, especially during the peak period of acute respiratory viral infections.

Do not eat raw or undercooked foods, unpasteurized milk, soft cheeses, raw eggs, or raw fish. Wash fruits and vegetables thoroughly before eating. Also, avoid alcohol.

Avoid strenuous physical activity and traumatic sports. Direct sun exposure and tanning beds are not recommended.

Do not take any dietary supplements, vitamin complexes, or herbal remedies without consulting your oncologist.

What can you eat after chemotherapy?

Proper nutrition is a key factor in successful recovery. Your diet should be balanced, high in protein, and calorie-sufficient to restore tissue and support the immune system. Include lean meat, poultry, fish, eggs, legumes, and dairy products in your diet.

Recommended complex carbohydrates: whole grain cereals, brown rice, durum wheat pasta, whole grain bread. Vegetables and fruits, dark green leafy vegetables, broccoli, carrots, tomatoes, berries, citrus fruits.

Drink at least 2-2.5 liters of fluids per day: pure water, weak teas, compotes, diluted juices.

How to ease the condition after chemotherapy?

To eliminate nausea and vomiting, eat small portions 5-6 times a day, avoid foods that are too hot or cold and foods with strong odors.

For mucositis and stomatitis, rinse your mouth with a saline solution or baking soda solution, use a soft toothbrush, and avoid irritating foods. Eating cold foods, ice cream, and ice also helps. For dry skin, use fragrance-free moisturizing creams and avoid hot showers.

If you experience chronic fatigue, rest during the day and establish a regular sleep schedule. For peripheral neuropathy, massage of the limbs, warm baths, and wearing comfortable shoes can help.