Understanding Chemotherapy

As we wrote in the Breast cancer article. One of the cancer treatments is Chemotherapy, which uses drugs that are often injected intravenously. Chemotherapy is one of the main categories of a medical discipline dedicated to the treatment of cancer, called medical oncology.

What’s Chemotherapy ?

Chemotherapy is the treatment of cancer with chemicals. It is therefore based on the administration of drugs, most often associated with each other, depending on its location and stage. This is called “combined chemotherapy”. Chemotherapy is adapted to each patient according to the type of cancer in order to offer the appropriate treatment. Its purpose is to kill cancer cells or prevent them from growing, no matter where they are in the body. It can be used alone or in conjunction with radiotherapy.

History of Chemotherapy

During the First World War 1, one of the horrors of trench warfare was a poisonous yellow cloud called mustard gas. For those unfortunately exposed, it makes the air unable to breathe, burns their eyes, and causes huge blisters on the exposed skin.
Scientists desperately tried to develop an antidote to deal with this vicious weapon of war. In the process, they discovered that this gas caused irreversible damage to the bone marrow of the affected soldiers, stopping their ability to produce blood cells.
Despite these terrible effects, it gave scientists an idea. Cancer cells and bone marrow have one characteristic in common: both replicate rapidly.
Researchers in 1930 studied this idea by injecting mustard gas-derived compounds into the veins of cancer patients. It takes time and trial and error to find a treatment that benefits more than harm. But by the end of the Second World War, they discovered what would later be called the first chemotherapy drug. There are more than 100 today.

When Chemotherapy is used ?

The doctor offers chemotherapy generally in three situations:

• Before surgery. This is called neoadjuvant chemotherapy. The purpose of this chemotherapy is to decrease the size of the tumor and facilitate the operation. It also aims to reduce the risk of cancer recurrence. In addition, it can quickly assess whether chemotherapy drugs are effective on the tumor.
• After complete tumor surgery, when the surgeon has removed all visible cancer cells. This is called adjuvant chemotherapy. The purpose of chemotherapy here is to reduce the risk of local or distant recurrence. Chemotherapy then completes the surgery.
• To treat metastases, which are cancer cells that have spread to other parts of the body. It is called metastatic chemotherapy.

Classes of Chemotherapy drugs

There are more than 100 anti-cancer drugs. Doctors divide these 100+ drugs into different groups.

• Alkylating agents : This group of drugs directly act on DNA to prevent cells from replicating themselves. These drugs kill cells at all stages of the cell cycle. Some examples of alkylating agents are chloramphenicol, cyclophosphamide, cisplatin, and carboplatin.
• Nitrosoureas : are a group of drugs that act like alkylating agents. These drugs slow down or stop the enzymes that help repair DNA. They do enter the brain, but many chemotherapy drugs do not. Examples are carmustine and lomustine.
• Anti-metabolites : are a drug that interfere with cellular RNA and DNA. Antimetabolites act when cells divide. Examples are fluorouracil, methotrexate and fludarabine.
• Plant alkaloids and natural products : is a medicine made from natural products. This group of drugs can block the ability of one cell to divide into two cells and repair cell damage. Examples are vincristine, paclitaxel and topotecan.
• Antitumor antibiotics : are an Anti-neoplastic medication that are made of microorganisms. These antibiotics don’t act like the antibiotics that treats infections. They may work in all phases of the cell cycle. They either break up DNA strands or slow down or stop DNA synthesis. Examples are Bleomycin, antibiotic drug and Mitoxantrone.
• Hormonal agents : There 2 two types of hormonal agents used in treatment of cancer: Corticosteroid hormones and sex hormones. 
  Corticosteroids are used to treat some cancers like leukemia, multiple myeloma, and lymphoma. Usage of Steroids includes also reduction of swelling around tumors of the brain and spinal cord. Steroids are used with other chemotherapy drugs in combination chemotherapy. Examples of corticosteroids are Prednisone and Dexamethasone. 
  Sex hormones are the female and male hormones. They can be used to control the growth of breast, uterine and prostate cancers. These drugs do not kill cells, as typical chemo drugs do. They cut off the “food supply” to destroy the cancer cells. Examples of sex hormones are Tamoxifen and Leuprolide.
• Biological response modifiers : these drugs strengthen the bodies immune system to fight the growth of cancer. Other agents might stop or slow cancer growth by disrupting processes that are needed to grow or spread. This group of anti-cancer drugs is often considered separate from chemotherapy. Examples of biological response modifiers are Herceptin and Avastin, Erbitux and Rituxan.
  

Chemotherapy drugs are given either by infusion into a blood vessel or by mouth as capsules or tablets. The drugs can also be injected into a tibialis or gluteus muscle, under the skin, into a vein, into the cerebrospinal fluid, into a body cavity, or directly into the tumor. Chemotherapy drugs can also be applied directly to the skin as an ointment (for non-melanoma skin cancer).

These are not methods to choose from: each drug and each situation has its preferred method. Sometimes more than one solution can be combined to deliver chemotherapy.

Side effects of Chemotherapy

Chemotherapy can cause unpleasant side effects, but many side effects can be treated or prevented. Once your treatment stops, most of them will pass.

• Tiredness (fatigue) is one of the most common side effects of chemotherapy. It can help get enough rest, avoid tasks or activities that you feel uncomfortable with, and do some light exercises such as walking or yoga. If you can, please ask your friends and family for help to complete daily tasks.
  If you suddenly feel very tired and breathless, please contact your care team. This may be a sign of anemia.
• Many people undergoing chemotherapy have periods of nausea or sickness (vomiting). Your care team can provide you with anti-disease (antiemetic) medicine to reduce or prevent this condition.
• Hair loss is a common side effect of chemotherapy, but it does not happen to everyone. Hair loss is almost always temporary. After the treatment, your hair should grow back soon.
  It may be possible to reduce the chances of hair loss by wearing a cold cap while you’re having chemotherapy.
• Chemotherapy can reduce your body’s ability to fight infection. It’s better to take precautions to protect yourself against infection by washing your hands regularly with soap and water, trying to avoid close contact with people who have an infection like the flu. Antibiotics may sometimes be prescribed to reduce your risk of getting an infection.
• Chemotherapy lowers your amount of red blood cells, which carry oxygen around the body. If your red blood cell count drops too low, you’ll develop anemia. Try to include a high amount of iron in your diet to help reduce your risk of anemia.
• This treatment can also reduce the number of platelets in your blood. These help stop severe bleeding when you cut or injure yourself. Tell your care team if you experience these problems. You may need treatment to increase the number of platelets in your blood.
• Chemotherapy can sometimes make the lining of the mouth sore and irritated. This is known as mucositis. Tell your care team if you have this issue, they may recommend painkillers or a special mouthwash.
• You may lose your appetite, too, but you should try to drink plenty of fluids and just eat what you can. It may help if you eat smaller meals more often instead of 3 large meals, try to eat healthy snacks regularly.
• Some chemotherapy medicines can cause temporary changes to your skin : dryness, slightly discolored, sensitive to sunlight, itchiness. Talk to your care team, they can advise you about creams that can help.
• Some people may have difficulties with their short-term memory, concentration and attention. You may find that routines tasks take much longer than usual. Doing some mental exercises, eating healthy food, and getting enough rest may be useful.
• Some people may experiment insomnia. To improve your sleep, you can set regular times for going to bed and waking up, try taking a warm bath to relax, avoid caffeine, nicotine, alcohol, heavy meals and exercise for a few hours before going to bed, avoid watching TV or using a phone, tablet or computer shortly before going to bed.
• Many people find that they lose interest in sex during chemotherapy. This is usually temporary, and your things should gradually return to normal after your treatment has finished. Before starting treatment, ask your care team whether your fertility may be affected. If you’re at risk of infertility, they will discuss your options with you. You should avoid becoming pregnant during your treatment, as chemotherapy medicines could harm the baby. 
• You may have diarrhea or constipation a few days after you begin chemotherapy. Diets and some medicines can help in these situations.
• Having chemotherapy can be a frustrating, stressful and maybe even traumatic experience. It’s natural to feel anxious or even depressed. If you feel that way, try to ask your doctor and discuss possible treatment strategies.

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