Cancer Chemotherapy

What is chemotherapy?

Chemotherapy is the use of medications to treat cancer. It has played a major role in cancer treatment for half a century. Years of testing and research have proved chemotherapy to be an effective cancer treatment. It may be the only treatment, or it may be used in combination with other treatments, such as surgery and radiation therapy.

Chemotherapy works by killing rapidly dividing cells. These cells include cancer cells, which continuously divide to form more cells, and healthy cells that divide quickly, such as those in the bone marrow, gastrointestinal tract, reproductive system and hair follicles. Healthy cells usually recover shortly after chemotherapy is complete.

What is chemotherapy used for?

The main advantages of chemotherapy are that unlike radiation, which treats only the area of the body exposed to the radiation, chemotherapy treats the entire body. As a result, any cells that may have escaped from the original cancer are treated.
Depending on what type of cancer a person has, the doctor may use chemotherapy to:

• Eliminate all cancer cells in the body, even when cancer is widespread
• Prolong the life by controlling cancer growth and spread
• Relieve symptoms and enhance the quality of life

In some cases, chemotherapy may be the only treatment. But more often, it is used in conjunction with other treatments, such as surgery, radiation or a bone marrow transplant, to improve results. For example:

Neoadjuvant therapy: The goal of neoadjuvant therapy is to reduce the size of a tumour before surgery or radiation therapy.

Adjuvant therapy: This is given after surgery or radiation. The goal of adjuvant therapy is to eliminate any cancer cells that might linger in the body after earlier treatments.

What are the types of chemotherapy?

Chemotherapy may not be limited to a single drug. Most chemotherapy is given as a combination of drugs that work together to kill cancer cells. Combining drugs that have different actions at the cellular level may help destroy a greater number of cancer cells and might reduce the risk of cancer developing resistance to one particular drug. The doctor will recommend drug combinations that have been tested in people with similar conditions and have been shown to have some effect against the particular type of cancer.

What chemical the doctor recommends is generally based on the type, stage and grade of the cancer, as well as the person's age, general health and willingness to tolerate certain temporary side effects.

Some types of chemotherapy medications commonly used to treat cancer include:

1. Alkylating agents: These medications interfere with the growth of cancer cells by blocking the replication of DNA. Example: Mechlorethamine
   
2. Antimetabolites: These drugs block the enzymes needed by cancer cells to live and grow. Example: Methotrexate.
   
3. Anti-tumour antibiotics: These antibiotics are different from those used to treat bacterial infections and interfere with DNA, blocking certain enzymes and cell division and changing cell membranes. Example: Doxorubicin
   
4. Mitotic inhibitors: These drugs inhibit cell division or hinder certain enzymes necessary in the cell reproduction process. Example: Etoposide and Vinorelbine
   
5. Nitrosoureas: These medications impede enzymes that repair DNA. Example: Cisplatin and Cisplatinum.

How is chemotherapy given?

One usually receives chemotherapy in cycles, depending on the condition and the type of drugs used. Cycles may include taking the drugs daily, weekly or monthly for a few months or several months, with a recovery period after each treatment. Recovery period allows the body to rest and produce new, healthy cells.

Chemotherapy drugs can be taken in a number of forms. The treating doctor determines what form(s) to use primarily based on what type of cancer a person has and what drug(s) will best treat the cancer. Chemotherapy is given through the following methods:

1. Intravenous (IV): Chemotherapy is injected into a vein, using a needle inserted through the skin. This allows rapid distribution of the chemotherapy throughout the body.
   
2. Oral: The patient swallows this kind of chemotherapy as a pill.
   
3. Topical: This type of drug is applied to the skin to treat localised skin cancers.
   
4. Injection: The doctor injects the drug directly into the muscle using a needle on the skin or into a cancerous area on the skin.

Chemotherapy medications, regardless of how they're given, generally travel in the bloodstream and throughout the body. The intravenous route is the most common, allowing chemotherapy drugs to spread quickly through the system. In cases where the doctor wants to direct chemotherapy to a more confined area, for example, to ensure a tumour is exposed to more of the drug, he may insert a catheter directly into that area or into a blood vessel supplying the tumour.

What are the various side effects of chemotherapy?

Since chemotherapy drugs can affect healthy cells, one of their disadvantages is that the person may experience side effects, some temporary and some long term. Not every drug will cause every side effect. The treating doctor can tell what to expect from the drugs.

Temporary side effects might include:

• Hair loss
• Dry mouth
• Mouth sores (stomatitis)
• Difficult or painful swallowing (oesophagitis)
• Nausea
• Vomiting
• Diarrhoea
• Constipation
• Fatigue
• Bleeding
• Susceptibility to infection
• Infertility
• Loss of appetite
• Changes in the way food tastes
• Cognitive impairment, sometimes referred to as chemo brain
• Liver damage

How long these temporary side effects last, depends on what drug(s) are being taken and for how long. Most side effects subside shortly after the chemotherapy treatment is stopped. Most short-term side effects can be minimised with medication. For example, the doctor can give medications to help relieve nausea or build up the blood counts. One must always tell the doctor if one is uncomfortable with a side effect. If the side effects are more than one is willing to endure, one can change treatments.

As people with cancer are living longer after treatment, doctors have discovered that some treatments cause long-lasting side effects or side effects that become apparent long after treatment ends. These long-term side effects are rare. Before one begins treatment, one must discuss with the doctor about the long-term effects. Some chemotherapy drugs can cause:

• Organ damage, including problems with heart, lungs and kidneys
  
• Nerve damage
  
• Blood in urine (haemorrhagic cystitis)
  
• Another cancer, including Hodgkin's disease and non-Hodgkin's lymphoma, leukaemia and some tumours
  
• Infertility

The doctor can explain about the signs and symptoms to watch for after the treatment. Knowing what long-term side effects to watch for can help one stay healthy after treatment.

While beginning chemotherapy can be frightening, one must know that new medications are helping reduce unpleasant side effects. But chemotherapy will always cause some significant side effects. One must keep in mind that many people with cancer are living longer than ever - thanks partly to chemotherapy.