Cancer by far is our worst enemy. Forget about guns because you can heal quickly from a gun wound. Cancer is one of those diseases that kills you from the inside. It lurks within your body undetected until one day you go to the doctor for a check-up and something came back abnormal. Once the prognosis is there, the next dreaded word is chemotherapy (#chemo). The word is out on chemo and how devastating it actually is. It will debilitate you in the name of your salvation. The question I always have is what exactly is chemotherapy and how does chemotherapy work?
What Is Chemotherapy?
The chemotherapy (#chemotherapy) definition overlaps not just one thing but rather a range of treatments towards killing cancer. It can be one drug or a combination of drugs. There are over 100 current drugs being used for chemotherapy and these drugs are considered antineoplastic drugs. Antineoplastic by definition inhibits or prevents the growth and spread of tumors or malignant cells. The intended use of these drugs can include preventing the cancer from spreading, slow the cancer’s growth, killing cancer obviously, kill cancer cells that spread to other parts of the body and to relieve symptoms such as pain and blockages caused by cancer. In addition to this form of treatment there is also surgery and radiation treatments used.
There are different delivery methods for these drugs with the most common being in an IV bag. In movies, people receiving IV chemotherapy drugs are often in comfortable chairs with tubes attached to their arms. There are also oral chemotherapy drugs that come in the form of a pill, liquid or even as a flu shot. Listed below will be the various types of chemotherapy drugs and a brief explanation in their use.
The first type is called Alkylating agents. Alkylating agents are drugs that directly affect the DNA of cells and prevent them from replicating so they can’t grow. There are drawbacks to this approach since healthy cells are affected and can even affect your bone marrow with long-term use. The bone marrow is that fleshy tissue inside your bones and is important because that is the site of red blood cells, white blood cells and stem cells. Over use of these types of drugs can lead to leukemia which is a bone marrow cancer with abnormally high white blood cell count. From this group there are different classes of Alkylating agents which include Nitrogen mustards (mechlorethamine, ifosfamide, chlorambucil and cyclophosphamide), Nitrosoureas (streptozocin and carmustine), Alkyl sulfonates, Triazines ( dacarbazine and temozolomide), Ethylenimines (thiotepa and altretamine) and Platinum drugs (cisplatin, carboplatin, and oxalaplatin).
The next class of chemotherapy drugs are called antimetabolites. Each cell has a growth cycle in which it divides to grow. There are several steps in the cycle but an important one is called the S phase. In this portion of the cycle, the DNA of the cell which is stored in chromosomes creates identical copies of itself. The DNA strand will unwind, split and metabolites or organic compounds will be added to make an exact copy. Any change or deformity in the copy of the DNA strand will cause genetic defects that can kill the cell or make it cancer. These drugs are commonly used to treat leukemias, cancers of the breast, ovary, and the intestinal tract. Some of the common antimetabolites include: fluorouracil, 6-mercaptopurine, Capecitabine, Cytarabine, Floxuridine, Fludarabine, Gemcitabine, Hydroxyurea, Methotrexate and Pemetrexed.
The next type of drugs are called anti-tumor antibiotics. When you think of antibiotics, you think of the treatment of viral or bacterial infections. These drugs are not like those antibiotics. These versions work by changing the DNA inside cancer cells to keep them from growing and multiplying. One main group of these anti-tumor antibiotics are called anthracyclines which interfere with enzymes involved in the DNA replication cycle. The can impact the entire life cycle of a cell and not just a certain phase. Some examples of anthracyclines include: Daunorubicin, Doxorubicin, Epirubicin and Idarubicin. Although the treatment sounds ideal for all types of cancers, a major concern when using these drugs is the permanent damage to the heart when used high doses. Based on this information, a person can only take a certain amount of their lifetime when being treated with anthracyclines. There are other anti-tumor antibiotics that are not anthracyclines such as Actinomycin-D, Bleomycin, Mitomycin-C and Mitoxantrone.
The next class of chemo drugs are called topoisomerase inhibitors. Topoisomerase is an enzyme used in cell division to the separate the strands of DNA so they can be copied during the S phase. If they can’t copy themselves then they can’t grow. These inhibitors are popular when treating certain leukemias, as well as lung, ovarian and gastrointestinal cancers. Topoisomerase inhibitors are grouped according to which type of enzyme they affect. Topoisomerase 1 inhibitors include Topotecan and Irinotecan while topoisomerase 2 include Etoposide, Teniposide and Mitoxantrone. One little drawback is that topoisomerase 2 inhibitors can increase the risk of a second cancer called acute myelogenous leukemia (AML) if used after 2 to 3 years.
The next class of chemotherapy drugs are called mitotic inhibitors. These drugs are derived from natural plant sources and are often plant alkaloids. Plant alkaloids are naturally occurring chemical compounds in plants that contain mostly nitrogen atoms. These compounds work by stopping mitosis which is the cell division into two genetically identical daughter cells. These inhibitors keep enzymes from making proteins needed for cell reproduction. They stop mitosis in all of your cells and not a specific area. They are used to treat many different types of cancer including breast, lung, myelomas, lymphomas, and leukemias. These drugs may cause nerve damage which can limit the amount that can be given. Some typical mitotic inhibitors include taxanes like paclitaxel and docetaxel, epothilones like ixabepilone, vinca alkaloids like vinblastine, vincristine, and vinorelbine and estramustine.
The final group of drugs are called corticosteroids, which are often simply called steroids. These are natural hormones and hormone-like drugs that are useful in the treatment of many types of cancer, as well as other illnesses. When these drugs are used as part of cancer treatment, they are considered chemotherapy drugs. Well known steroids include prednisone, methylprednisolone and dexamethasone. Steroids are also commonly used to help prevent nausea and vomiting caused by chemotherapy. They are used before chemotherapy to help prevent severe allergic reactions, too.
Now that you have an understanding of the different types of drugs available, you also need to know what other options are done in addition to using prescription drugs. The first option is having the tumor surgically removed as long as it doesn’t interfere or is attached with other organs. The intent of surgery is not just remove the tumor but also healthy cells around it to prevent regrowth. This is tricky since leaving even one cell can cause regrowth if not properly neutralized.
A second option is radiation when surgery is not an available option. When one thinks radiation, you automatically think of X-rays or UV light from the sun. There are a lot of products in our society that emit some form of ration such as phones, electrical wires and microwaves. Radiation used for the treatment of cancer is much stronger than a typical X-ray. The intent is to use radiation particles in a targeted area to kill off cancer cells. This process is not cancer specific. by this I mean that the radiation will target healthy and cancerous cells. As technology improves, we see new methods such as proton beam radiation which is highly selective in its use. The side effects are mostly within where the targeted area is but you will feel tiredness and fatigue.
The side effects of chemotherapy not only impacts the patients but also the health care workers from the doctors, to the pharmacists to the dock workers. For patients, the road is a hard one and symptoms will vary but lets start with the most common chemo side effects which include attention or memory problems, fatigue, constipation, hair loss, difficulty chewing, dry mouth, weight loss, hormone deprivation in men, menopause symptoms in women, mouth sores, osteoporosis, bleeding and clotting problems, greater chance of infection, dehydration, diarrhea, headaches, nausea, shortness of breathe, various skin conditions, taste changes, constant urge to urinate, anemia (lack of red blood cells) and Lymphedema (swelling in your arms and legs). These are some of the conditions that you may experience. You also have to keep in mind that your immune system will be very weak so something as simple as the flu can actually kill you.
The health care workers can be affected if proper protection is not used when handling these drugs. Exposure usually comes from the skin and can experience similar symptoms above, but there are some long-term side effects found which include liver and kidney damage, damage to the bone marrow, damage to the lungs and heart, infertility (temporary and permanent), negative effects on reproduction and the developing fetus in pregnant women, hearing impairment and other forms of cancer. These symptoms are possible due to exposure alone since they are meant to basically kill cells in your body.
Have you or a loved one experienced chemotherapy side effects?