July 13, 2024
Medical Science



Last Update on September 14, 2022

| How does chemotherapy work? | Why Chemotherapy is used? | Drugs | Side Effects |

Chemotherapy is a medical therapy that uses heavy chemicals to destroy cancer cells and stop the growth and division of cells in the body.

The term “Chemotherapy” (“chemo”) is frequently used to describe treatments for cancer. But not all cancer medications function in the same way. The medications used in conventional or traditional chemotherapy are cytotoxic, which means they can destroy tumor cells. Knowing how traditional or standard chemotherapy functions and what to anticipate can often help you be ready for treatment and make wise healthcare decisions if your treatment plan calls for it.

Chemotherapy is most frequently used for the treatment of cancer because cancer cells reproduce and develop more rapidly than the majority of body cells.

Chemotherapy medications come in a wide variety. A number of malignancies can be treated with chemotherapy medications either alone or in combination.

Although chemotherapy is a successful treatment for many cancer types, there is a chance that it will have adverse effects. While some side effects of chemotherapy are minor and manageable, others might have negative consequences.

1. How does chemotherapy work to treat cancer?

Chemotherapy is a drug that affects the whole body. This indicates that it circulates throughout the body through the bloodstream.

Chemotherapy drugs can be classified according to how they function, their chemical makeup, and their connections to other medicines. Some medications have multiple modes of action and can be found in multiple categories.

Chemotherapy is available in a variety of kinds. The medications used in the therapy, generally are potent chemicals that kill cancerous cells at particular times of the cell cycle. The cell cycle is the process through which new cells are created in all living things. This therapy has a greater impact on these rapidly proliferating cells because cancer cells go through this phase more quickly than normal cells.

This therapy can harm healthy cells as they go through their natural cell cycle since it circulates throughout the entire body. This explains why chemotherapy side effects including nausea and hair loss might occur.

2. Why Chemotherapy is used?

The aims of chemotherapy vary depending on the type of cancer you have and the extent of its dissemination. Chemotherapy can be done on its own or as a component of a comprehensive treatment strategy. The therapy is used in different ways to treat cancer, including:

As the primary treatment: Chemotherapy treatments usually aim to completely remove cancer while preventing its re-growth. One could refer to this as “curative chemotherapy.”

Before other treatments: Before undergoing surgery or radiation therapy, cancers can be controlled using chemotherapy. This is referred to as Neoadjuvant chemotherapy.

After other treatments: To remove any remaining cancer cells, chemotherapy can be performed following surgery or radiation treatment. The chemotherapy is called “adjuvant chemotherapyā€¯.

To show-done the growth of cancer cells: The therapy can be partially reduced cancers and stop cancer cells develop and spreading for varying periods of time, even when the cancer is incurable. Chemotherapy can increase the quality of life, reduce cancer-related symptoms, and increase survival in these circumstances. Palliative chemotherapy is the term sometimes used to describe this type of treatment.

Several cancers can be treated with chemotherapy. Both metastatic cancer and recurrent cancer can be treated with it. Cancer that returns after therapy is called recurrent cancer. Cancer that has metastasized means it has spread to different organ systems.

3. Chemotherapy Drugs:

Chemotherapy drugs can be defined according to how they function, their chemical makeup, and their connections to other medications. Some medications have multiple modes of action and can be found in multiple categories.

Based on their chemical compositions and how they interact with cancer cells, chemotherapeutic drugs can be divided into the following major categories (classes):

  • Alkylating agents
  • Nitrosoureas
  • Antimetabolites
  • Anti-tumor antibiotics
  • Topoisomerase inhibitors
  • Mitotic inhibitors
  • Corticosteroids

3.1. Alkylating agents:

Alkylating agents damage the DNA of the cell, preventing it from replicating (creating duplicates of it. This drug is used to treat Leukemia, lymphoma, Hodgkin’s disease, multiple myeloma, sarcoma, and cancers of the lung, breast, and ovary are just a few cancers.  Alkylating agents also affect all division phases of the cell cycle.

These drugs can harm the bone marrow cells that produce new blood cells because they harm DNA. Rarely, this can result in leukemia. Alkylating drugs carry a “dose-dependent” risk of leukemia, which means that the risk is minimal at lower doses but increases as the overall amount of the medicine taken increases. About 5 to 10 years after using alkylating drugs, the chance of developing leukemia is at its maximum.

 Alkylating agents list:

  • Altretamine
  • Bendamustine
  • Busulfan
  • Carboplatin
  • Carmustine
  • Chlorambucil
  • Cisplatin
  • Cyclophosphamide
  • Dacarbazine
  • Ifosfamide
  • Lomustine
  • Mechlorethamine
  • Melphalan
  • Oxaliplatin
  • Temozolomide
  • Thiotepa
  • Trabectedin

3.2. Nitrosoureas:

Alkylating agents known as nitrosoureas have a unique effect. Nitrosoureas can enter the brain, while the other alkylating substances mentioned above cannot.

Nitrosoureas drugs can enter the brain because they can pass through the blood-brain barrier, a unique barrier that prevents most medications from entering the brain. These medications can be used to treat specific kinds of brain tumors because of this activity.

Nitrosoureas drugs list:

  • Carmustine
  • Lomustine
  • Streptozocin

2.3. Antimetabolites:

Antimetabolites work as a replacement for the usual building blocks of RNA and DNA, interfering with their normal function. A cell cannot reproduce when this occurs since the DNA is unable to replicate itself. They are frequently employed to treat leukemias, as well as breast, ovarian, intestinal, and other malignancies.

Antimetabolites drugs list:

  • Azacitidine
  • 5-fluorouracil (5-FU)
  • 6-mercaptopurine (6-MP)
  • Capecitabine (Xeloda)
  • Cladribine
  • Clofarabine
  • Cytarabine (Ara-C)
  • Decitabine
  • Floxuridine
  • Fludarabine
  • Gemcitabine (Gemzar)
  • Hydroxyurea
  • Methotrexate
  • Nelarabine
  • Pemetrexed (Alimta)
  • Pentostatin
  • Pralatrexate
  • Thioguanine
  • Trifluridine/tipiracil combination

3.4. Anti-tumor antibiotics:

These drugs differ from the antibiotics that are used to treat infections. They function by altering the DNA of cancer cells to stop them from proliferating and developing.

3.4.1. Anthracyclines:

Anti-tumor drugs called anthracyclines prevent enzymes from copying DNA during the cell cycle. They attach to DNA, preventing it from duplicating itself and preventing cell reproduction. (Proteins known as enzymes help initiate, facilitate, or quicken the rate of chemical reactions in cells.) They are frequently employed to treat various malignancies.

Anthracyclines drugs list:

  • Daunorubicin
  • Doxorubicin (Adriamycin)
  • Doxorubicin liposomal
  • Epirubicin
  • Idarubicin
  • Valrubicin

Given in large quantities, these medications have the potential to cause irreversible cardiac damage, which is a big worry. For this reason, these medications frequently have lifetime dose limitations (also known as cumulative doses).

Anti-tumor antibiotics list:

  • Bleomycin
  • Dactinomycin
  • Mitomycin-C
  • Mitoxantrone

3.5. Topoisomerase inhibitors:

Plant alkaloids are another name for Topoisomerase inhibitors. They obstruct topoisomerase enzymes, which aid in separating DNA strands so that they can be duplicated. (Proteins called enzymes are responsible for the chemical reactions in living cells.) Topoisomerase inhibitors are prescribed for the treatment of pancreatic, lung, ovarian, gastrointestinal, colorectal, and some types of leukemia.

Topoisomerase 1 inhibitors list:

  • Irinotecan
  • Irinotecan liposomal
  • Topotecan

Topoisomerase 2 inhibitors list:

  • Etoposide (VP-16)
  • Mitoxantrone
  • Teniposide

3.6. Mitotic inhibitors:

Plant alkaloids are another name for mitotic inhibitors. They are chemicals made from natural resources, like plants. They function by preventing cell division, but because they prevent enzymes from producing proteins necessary for cell reproduction, they can harm cells at any stage of the cell cycle.

Mitotic inhibitors are two types, Taxanes, and Vinca alkaloids.

Taxanes drugs list:

  • Cabazitaxel
  • Docetaxel
  • Nab-paclitaxel
  • Paclitaxel

Vinca alkaloids Drugs list:

  • Vinblastine
  • Vincristine
  • Vincristine liposomal
  • Vinorelbine

These drugs are used in the treatment of a wide range of cancers, including leukemias, myelomas, lymphomas, and breast, lung, and myeloma. The amount that can be administered is because of the possibility of nerve damage from these medications.

3.7. Corticosteroids:

Steroids, often known as corticosteroids, are natural hormones and hormone-like substances that are effective in treating a variety of cancers as well as other conditions. These medications are referred to as chemotherapy medications when they are used to treat cancer.

Corticosteroids drugs list:

  • Prednisone
  • Methylprednisolone
  • Dexamethasone

Some other chemotherapy drugs listed:

  • All-trans-retinoic acid
  • Arsenic trioxide
  • Asparaginase
  • Eribulin
  • Hydroxyurea
  • Ixabepilone
  • Mitotane
  • Omacetaxine
  • Pegaspargase
  • Procarbazine
  • Romidepsin
  • Vorinostat

4. Common side effects of chemotherapy:

Most people are concerned with whether they will experience chemotherapy side effects and, if so, what those adverse effects would be like. Here are a few of the most typical negative effects of the therapy:

  • Fatigue
  • Hair loss
  • Easy bruising and bleeding
  • Infection
  • Anemia
  • Nausea and vomiting
  • Appetite changes
  • Constipation
  • Diarrhea
  • Mouth, tongue, and throat problems
  • Peripheral neuropathy or other nerve disorder
  • Skin and nail problems
  • Urine and bladder issues and kidney failure
  • Weight changes
  • Chemo brain
  • Mood changes
  • Changes in libido and sexual function
  • Fertility problems