Chemotherapy at a glance
- Chemotherapy is the use of powerful chemical drugs to kill cancer cells.
- Chemotherapy is most often a systemic treatment, meaning the drugs travel throughout the body to attack cancer cells anywhere they are found.
- The three goals of chemotherapy for cancer are to cure, control or relieve suffering.
- More than 100 chemotherapy drugs are used to treat many types of cancer.
- These chemotherapy drugs differ in their chemical composition, effectiveness against the cancers they target and side effects, which range from mild discomfort to serious complications.
What is chemotherapy?
Chemotherapy actually means using any drug to treat any disease, but it is most commonly associated with treating cancer. Chemotherapy, or “chemo,” uses strong drugs to treat abnormally fast-growing cells anywhere in the body. It is a common cancer treatment since cancer cells grow faster than any other cells. Chemotherapy is also used to treat bone marrow disease and immune system disorders.
Chemotherapy is often the first-line of treatment for many forms of cancer, and may also be used in conjunction with, following and/or preceding other therapies, such as radiation, biological therapy and surgery. Chemo can be used prior to surgery or radiation to shrink a tumor, or afterward to destroy remaining cancer cells. A novel approach called Hyperthermic Intraperitoneal Chemotherapy (HIPEC) actually heats up the chemo agent prior to it being administered immediately after surgery. Surgery and radiation treatments focus on one part of the body, whereas chemotherapy travels throughout the body to attack cancer cells anywhere they are present. This is known as a systematic treatment.
Chemotherapy works by killing cancer cells, usually by attacking them at a specific stage of their reproduction. All cells, cancerous or not, go through a regeneration process to replace cells that die from injury or normal wear. This process is called the “cell cycle” and involves five phases, with a cell reproducing an identical copy of itself during the mitosis phase then entering the resting stage. Both cells repeat this cycle when new cells are needed.
Chemotherapy drugs attack cancer cells during the reproduction cycle, but never at the resting phase. Many chemo drugs are designed to attack cells of certain types of cancer at a particular phase of the cell cycle.
Oncologists are experts at knowing how these various chemotherapy drugs work on different cancers and devising a plan for administering specific doses timed to attack a cancer cell at a particular phase of its cycle. They can also predict how different chemotherapy drugs will work together to kill cancer cells.
Unfortunately chemotherapy also kills normal cells, because the drugs can’t differentiate between a cancer cell and a normal cell undergoing reproduction and not in the resting phase. With each chemo treatment, oncologists must balance its effectiveness against cancer with the destruction of normal cells, which is what causes side effects of chemo.
Cancer is notoriously difficult to treat, and our understanding of the disease itself is incomplete. Accordingly, chemo is generally effective in three ways:
- Symptomatic relief
The goal of any cancer treatment is to cure the patient, causing the cancer to disappear and never return. Chemotherapy has cured cancer, but most doctors speak of the curative intent of chemotherapy, because a cure is often elusive. Even if a cancer does disappear after chemotherapy, it can come back years later, so it was not cured.
Short of curing cancer, chemotherapy attempts to control cancer — to stop it from spreading and shrink the existing cancer tumors. Controlling cancer can make the patient feel better physically and emotionally and help him or her live longer. Chemotherapy can help manage remaining cancer, thereby reducing symptoms, pain and effects on the body. If a cancer has been temporarily eradicated, chemo can help extend the time before the cancer returns.
Chemotherapy can offer relief, or palliation, from advanced stage cancer that cannot be cured or controlled. Chemo can reduce the symptoms of cancer, allowing the patient to live as comfortably as possible under the debilitating influence of advanced stage cancer.
How are chemotherapy treatments given?
Chemotherapy drugs are administered differently depending on the type of cancer, its stage and other factors related to the patient’s specific condition and health. For instance, a chemo drug that can be given orally may have to be given by injection because the patient’s digestive system can’t absorb the drug. Options for chemo delivery are:
- Intravenous, injected into a vein, usually in a continuous drip through a catheter
- Injected under the skin (subcutaneous)
- Topically, as a cream
- Injected into a muscle.
Chemotherapy treatment can take place in a hospital, a doctor’s office, the patient’s home, and even at work. Where chemotherapy is administered depends on several factors:
- Type of drugs to be used
- How they need to be administered (oral, type of injection)
- Personal preference
- Insurance coverage
- Regimen of dosing
- Patient monitoring required.
In deciding where and how to administer chemo, the oncologist will consider the specific drug, the dose, anticipated side effects and the patient’s general health. For example, a 24-hour IV infusion would likely be done in a hospital. In other instances, a portable pump worn by the patient at home or work may be the desired delivery system.
In some cases chemotherapy can be applied locally to specific body areas, such as the abdomen, bladder and chest cavity. Discs containing chemo drugs can also be placed next to a tumor during surgery. A chemotherapy cream can be applied to certain skin cancers.
Who should consider chemotherapy treatments?
Chemotherapy is used to treat a variety of cancers, so that it can be appropriate for a wide range of patients. Since there are many types of chemotherapy drugs, many types of cancers and many variables related to specific conditions, the decision to use chemotherapy or not is generally made by both the oncologist and the patient.
Patient preference is a significant factor in determining use of chemotherapy. The stage and type of cancer, the patient’s health, and the prospects for cure or control must all be considered. Some cancer patients are anxious to receive chemotherapy to help fight cancer, while others decide not to undergo chemo at all, often after weighting the chance of improvement against side effect discomfort and damage.
What are the risks of chemotherapy treatments?
Risks from chemotherapy usually relate to side effects caused by the destruction of normal cells or by the body’s reaction to the specific drug(s) being used. Oncologists know how to prevent many side effects associated with the chemotherapy being given. They can also use medications to treat those side effects, reducing the discomfort and damage they can cause.
Side effects can be short-term and disappear once chemotherapy treatments end, or they can be “late side effects” that don’t appear until months after chemotherapy has ceased. Many factors can cause or alter the side effects of a patient experience, and these may change throughout chemotherapy.
Most chemo side effects are due to the destruction of normal cells. Since chemotherapy targets all fast growing cells, such as bone marrow, digestive tract lining, hair follicle and reproductive tract lining cells, these areas of the body are likely to experience side effects.
Short-term side effects include:
- Vomiting, nausea and/or diarrhea
- Loss of appetite
Some foods can assist in reducing short-term side effects. For example, clear liquids can help with diarrhea and liquid foods can help counteract loss of appetite.
Late side effects can include:
- Appearance of a new cancer
- Lung tissue damage
- Kidney disorders
- Nerve damage.
In addition to side effects from the medications, patients may face risk of infection, soreness and swelling at the injection site. Oncologists discuss side effects and their possible management with patients before treatment begins.