Chemotherapy uses drugs to kill cancer cells and prevent a disease from spreading. It is one of the most common treatments for cancer. Doctors use chemotherapy alone or in combination with other treatments, such as surgery and radiation therapy, to maximize a patient's chance of survival.
Chemotherapy is a drug treatment that is primarily used to treat cancer. Chemotherapy drugs kill cancer cells, slowing down or stopping tumors from growing and spreading. Unlike other treatments that target a specific area, such as radiation therapy or surgery, chemotherapy is systemic, meaning the drugs affect the whole body.
Various chemotherapy drugs have different ways of working. Some directly damage the cancer cells' DNA, while others prevent cells from replicating their DNA. Both methods lead to cells that are unable to reproduce and multiply. Depending on the type of cancer, its stage, and the individual’s health, doctors may use chemotherapy to ease cancer symptoms, stop a cancer from growing, or attempt to cure it.
Chemotherapy drugs are a double-edged sword because they also affect healthy, noncancerous cells. However, letting cancer go untreated can be much worse. Without intervention, cancer continues to grow and spread, invading surrounding tissues and other healthy organs.
Chemotherapy is most often used to treat cancer, but it’s also used to treat bone marrow diseases and immune system disorders.
Cancer
Chemotherapy drugs are used to treat many types of cancer. The specific treatment depends on many factors, including the cancer type, whether it has spread, and your health.
Chemotherapy may be used before surgery to shrink a tumor (called neoadjuvant chemotherapy) or after surgery to kill any cancer cells that may be remaining (called adjuvant chemotherapy). Chemotherapy is also used when cancer returns, when it has spread to other areas of the body, or in combination with other therapies to help make them more effective.
Bone Marrow Diseases
Bone marrow is the soft tissue inside your bones. It makes blood cells. Chemotherapy may be used for bone marrow diseases to destroy cancerous or abnormal cells before a stem cell transplant.
Cancers that affect the bone marrow include leukemia, lymphoma, and myeloma. Noncancerous conditions include aplastic anemia, a rare condition in which the bone marrow stops producing enough blood cells, and severe combined immunodeficiency, a group of rare genetic disorders that affect the development and function of immune cells.
Autoimmune Diseases
Chemotherapy drugs are sometimes used to help treat certain autoimmune diseases, such as lupus and rheumatoid arthritis. With autoimmune disorders, the body’s immune system mistakenly attacks healthy cells in the body. Chemotherapy prevents cells from multiplying, thereby reducing the harm done by the immune cells.
Chemotherapy drugs are categorized by how they work, their chemical structure, and their relationship to other drugs. There are five main categories of chemotherapy drugs: alkylating agents, antimetabolites, antitumor antibiotics, topoisomerase inhibitors, and mitotic inhibitors. Not all chemo drugs fit into one of these categories, and some may belong to more than one. Alkylating agents are the most commonly prescribed type of chemotherapy drug.
Alkylating Agents
Alkylating agents stop cells from replicating by damaging their DNA. These drugs are given orally as pills or directly into your vein through an IV:
bendamustine (Bendeka)
busulfan
carboplatin (Paraplatin)
carmustine (Gliadel)
chlorambucil (Leukeran)
cisplatin (Platinol)
cyclophosphamide (Cytoxan)
dacarbazine (DTIC-Dome)
ifosfamide (Ifex)
lomustine (Gleostine)
lurbinectedin (Zepzelca)
melphalan (Alkeran)
oxaliplatin (Eloxatin)
procarbazine (Matulane)
streptozocin (Zanosar)
temozolomide (Temodar)
thiotepa (Thioplex)
trabectedin (Yondelis)
Antimetabolites
Antimetabolites mimic molecules that cells need to make DNA. The cancer cells are tricked into using the antimetabolite drug instead of what they need, and cancer cell replication is prevented.
Depending on the cancer that’s being treated and its stage, these antimetabolites are available in IV, injection, oral tablet, and topical (applied on the skin) forms:
5-fluorouracil
azacitidine (Vidaza)
capecitabine (Xeloda)
cladribine (Leustatin)
clofarabine (Clolar)
cytarabine (Cytosar-U)
decitabine (Dacogen)
floxuridine (FUDR)
fludarabine (Fludara)
gemcitabine (Gemzar)
hydroxyurea (Hydrea)
methotrexate (Trexall)
nelarabine (Arranon)
pemetrexed (Alimta)
pentostatin (Nipent)
pralatrexate (Folotyn)
thioguanine (Tabloid)
tipiracil and trifluridine (Lonsurf)
Antitumor Antibiotics
Antitumor antibiotics work by changing the DNA inside cells to prevent replication. Commonly given by IV or as an injection, some are available orally, but this is uncommon.
Antitumor antibiotics include the following:
bleomycin (Blenoxane)
dactinomycin (Cosmegen)
daunorubicin (Cerubidine)
doxorubicin (Adriamycin)
doxorubicin liposomal (Doxil)
epirubicin (Ellence)
idarubicin (Idamycin PFS)
mitomycin-C (Mutamycin)
mitoxantrone (Novantrone)
valrubicin (Valstar)
Topoisomerase Inhibitors
Topoisomerase inhibitors block topoisomerases, which are enzymes that separate DNA strands so they can be replicated. These drugs are given by IV or as pills:
etoposide (Vepesid)
irinotecan (Camptosar)
irinotecan liposomal (Onivyde)
mitoxantrone (Novantrone)
Teniposide (Vumon)
topotecan (Hycamtin)
Mitotic Inhibitors
Mitotic inhibitors interfere with cell division. These drugs are given by IV:
cabazitaxel (Jevtana)
docetaxel (Taxotere)
nab-paclitaxel (Abraxane)
paclitaxel (Onxol, Taxol)
vinblastine (Velban)
vincristine (Oncovin)
vincristine liposome (Marqibo)
vinorelbine (Navelbine)
Your body continuously generates new cells. When a new cell is formed, it goes through various phases to become a mature cell; this is called the cell cycle. Chemotherapy drugs target cells that are in various phases of the cell cycle to damage them.
Cancer cells replicate much faster than healthy cells. As they go through the cell cycle, they are a good target for chemotherapy drugs. All chemotherapy drugs work by preventing cell replication in some way. For example, alkylating agents directly damage DNA, while antimetabolites mimic the building blocks of RNA and DNA, preventing standard DNA replication. Mitotic inhibitors interfere with the production of proteins that are needed for cell replication.
Unfortunately, chemo drugs can’t differentiate between cancer cells and healthy ones, so they also damage healthy cells. The good news is that most healthy cells recover over time, whereas cancer cells usually don’t.
Chemotherapy can damage healthy cells, leading to a vast range of possible side effects. It is crucial that you take the drugs only as your doctor prescribes them and never share them with anyone else.
Lung damage, such as pneumonia and lung infections
Depending on your health history, the chemotherapy you need, and the length and frequency of treatment, you may be at a higher risk for other complications:
Drug Interactions Drug interactions can lead to serious health effects. Because of the large number of available chemotherapy drugs and the potential for drug interactions, tell your doctor about all of the other medications you are taking, including supplements, so they can find the safest medication for you.
Organ Damage Most chemotherapy drugs are metabolized by the kidneys or liver. People who have an underlying kidney or liver condition may need different medications to avoid damaging those organs.
Secondary Cancers Some chemotherapy drugs can increase the risk of a second cancer. Acute myeloid leukemia and acute lymphocytic leukemia are two secondary cancers that are linked to chemotherapy. The risk increases with the drug dosage, frequency, and treatment time.
QT Prolongation This is a rare but serious side effect of chemotherapy that can lead to a potentially fatal heart rhythm called torsade de pointes (TdP). Doctors use IV medications to bring the heart rate back to normal. In severe cases of TdP, a patient may need to stop or alter the chemotherapy.
Chemotherapy is a key cancer treatment. Although it's primarily used for cancer, chemotherapy is also an effective treatment for certain bone marrow and immune system disorders. These drugs can be used alone or in combination with other treatments for better effectiveness. Although chemotherapy can be very effective against cancer, it can cause a wide range of side effects. Be sure to discuss your health history and all of the medications you’re currently taking with your doctor before starting treatment.
