Chemotherapy is the systemic (whole body) treatment of cancer with anticancer drugs.
Purpose
The main purpose of chemotherapy is to kill cancer cells. It can be used as the primary form of treatment or as a supplement to other treatments. Chemotherapy is often used to treat patients with cancer that has spread from the place in the body where it started (metastasized), but it may also be used the keep cancer from coming back (adjuvant therapy). Chemotherapy destroys cancer cells anywhere in the body. It even kills cells that have broken off from the main tumor and traveled through the blood or lymph systems to other parts of the body.
Chemotherapy can cure some types of cancer. In some cases, it is used to slow the growth of cancer cells or to keep the cancer from spreading to other parts of the body. When a cancer has been removed by surgery, chemotherapy may be used to keep the cancer from coming back (adjuvant therapy). It is also helpful in reducing the tumor size prior to surgery (primary [neoadjuvant] chemotherapy). Chemotherapy can ease the symptoms of cancer (palliate), helping some patients have a better quality of life.
Types of chemotherapy
Chemotherapy may be used as the first line of treatment or it may be started after a tumor is removed. A variety of factors, including the type and stage of cancer, will determine the type of chemotherapy used.
Adjuvant chemotherapy
Adjuvant chemotherapy refers to giving patients anti-cancer drugs after the primary tumor has been removed and there is no evidence that cancer remains in the body. It was first studied in the 1950s. This form of treatment initially gained popularity because it showed promise in improving the survival for patients with certain cancers. The theory was that adjuvant chemotherapy would attack microscopic cancer cells that remained after tumor removal. Adjuvant chemotherapy may be effective in some types of cancers, including breast cancer, colorectal cancer, osteogenic sarcoma, and Wilms' tumor.
A patient's response to adjuvant therapy is determined by a variety of factors, including drug dosage, schedule of drug therapy, and drug resistance. Toxic side effects and cost-effectiveness are other important issues. This area is undergoing further investigation.
Primary (neoadjuvant) chemotherapy
Primary chemotherapy, also sometimes called neoadjuvant chemotherapy or induction chemotherapy, is the use of anticancer drugs as the main form of treatment. Chemotherapy can be the primary treatment with cancers such as these: certain lymphomas, childhood and some adult forms of Hodgkin's disease, Wilms' tumor, embryonal rhabdomyosarcoma, and small cell lung cancer.
Primary chemotherapy can also be used to treat tumors prior to surgery or radiation. In some cases, the tumor may be so large that surgery to remove it would destroy major organs or would be quite disfiguring. Primary neoadjuvant chemotherapy may reduce the tumor size, making it possible for a surgeon to perform a less traumatic operation. Examples of cancers in which primary chemotherapy may be followed-up with less extensive surgeries include: anal cancer, bladder cancer, breast cancer, esophageal cancer, laryngeal cancer, osteogenic sarcoma, and soft tissue sarcoma.
An advantage of primary chemotherapy is that the blood vessels are intact since they have not been exposed to surgery or radiation. Therefore, drugs can easily travel through the bloodstream toward the tumor. In fact, the therapy can improve the tumor's blood flow, making it more receptive to the impact of radiation. In addition, the use of chemotherapy before surgical removal of cancer allows the physician to assess the responsiveness of the tumor to the drug (s) used. Since not all chemotherapy regimens are equally effective, knowing how a particular tumor responds to the chemotherapy regimen prescribed can be an advantage in treating the disease.
Primary chemotherapy does have drawbacks. Some cancer cells may be drug-resistant, making the therapy ineffective. (Although discovering that the drug is ineffective minimizes the number of cycles of the drug that the patient must undergo.) The drug may not significantly reduce tumor size, or the tumor may continue to grow despite treatment. Furthermore, the initial use of a drug may lead to higher toxicity when chemotherapy is given later in the course of treatment.
Primary chemotherapy is becoming the norm in treating some patients with certain cancers, such as specific types of lymphomas, some small cell lung cancers, childhood cancers, head and neck cancers, and locally advanced breast cancer. Additional research using this type of chemotherapy is underway.
Combination chemotherapy
In most cases, single anticancer drugs cannot cure cancer alone. The use of two or more drugs together is often a more effective alternative. This approach is called combination chemotherapy. Scientific studies of different drug combinations help doctors learn which combinations work best for various types of cancers.
Combination chemotherapy provides a higher chance of destroying cancerous cells. An oncologist decides which chemotherapy drug or combination of drugs will work best for each patient. Different drugs attack cancer cells at varying stages of their growth cycles, making the combination a stronger weapon against cancerous cells. Furthermore, using a combination of drugs may reduce the chance of drug resistance.
When selecting the combination of drugs, a variety of factors are examined. It is important for each drug to be effective against the particular tumor being targeted. Toxicity must also be studied to be sure that each different drug used in a combination is not toxic for the same organ. For example, if two drugs are each toxic to the liver, the combination could be more damaging to that organ.
How chemotherapy is given
Chemotherapy medications enter a person's body in different ways, depending on the drugs to be given and the type of cancer.
The goal is for the chemotherapy drug to reach the tumor. Some areas of the body are less accessible for anticancer drugs, and this is considered when the doctor determines the route of administration. For example, the blood-brain barrier refers to the inability of some anticancer drugs to travel through the bloodstream and enter the brain or the fluid surround the brain. Areas of the body that are inaccessible to a particular drug create a phenomenon called the sanctuary effect. In other words, the tumor is safe because the chemotherapy cannot reach it. To overcome a problem such as this one, the doctor must consider the route that will most effectively deliver the drug to the cancerous cells. Chemotherapy may be given by one or more of the following methods:
oral (by mouth)
injection (intramuscular or subcutaneous)
intravenous (IV)
intra-arterial (into the arteries)
intralesional (directly into the tumor)
intraperitoneal (into the peritoneal cavity)
intrathecal (into the spinal fluid)
topically (applied to the skin)
Orally
Oral chemotherapy is given by mouth in the form a pill, capsule, or liquid. This is the easiest method and can usually be done at home.
Injection
Intramuscular (IM) chemotherapy is injected into a muscle. Chemotherapy given by intramuscular injection is absorbed into the blood more slowly than IV chemotherapy. Because of this, the effects of IM chemotherapy may last longer than chemotherapy given intravenously. Chemotherapy may also be injected subcutaneously (SQ or SC), which means under the skin.
Intravenous
Intravenous (IV) chemotherapy is the most common way to deliver anticancer drugs into a person's body. The drug is injected directly into a vein. A small needle is inserted into a vein on the hand or lower arm.
Chemotherapy may also be given by a catheter or port inserted into a central vein or body cavity, where it can remain for an extended period of time. A port is a small reservoir or container that is placed in a vein or under the skin in the area where the drug will be given. These methods eliminate the need for repeated injections and may allow patients to spend less time in the hospital while receiving chemotherapy. A common location for a permanent catheter is the external jugular vein in the neck. Catheters and ports require meticulous care and cleaning to avoid complications, such as blood clots or infection. They may be inserted using a surgical procedure.
Chemotherapy given by the IV method may be administered intermittently or continuously. The main reasons for a continuous flow are to increase effectiveness against the tumor or to lower toxicity. Some drugs perform more effectively when exposed to the cancer over a period of time, making a continuous flow more desirable. A drug that is commonly used to treat colorectal cancer in continuous infusions is fluorouracil, also known as 5-FU. A drug that has less toxicity to the heart with continued infusion is doxorubicin, also known as Adriamycin. In some cases, toxicity occurs when the drug reaches a peak level. Offering a continuous infusion prevents the drug from reaching this level, thus lowering the chance of toxic side effects.
Intra-arterial
Cancerous tumors require a supply of blood and oxygen so that they can grow. They get these essentials from the arteries that supply organs with their blood and oxygen. Putting chemotherapy drugs into the arteries provides good access to the cancerous tumor. Intra-arterial chemotherapy is not designed for all patients. The tumor must be confined to one specific organ and the blood supply to the tumor must be accessible. The liver is
Types of chemotherapy
Type
Definition
Adjuvant
Given to improve survival when cancer is no longer evident
Primary (formerly called
Use of chemotherapy drugs
neo-adjuvant)
as main treatment, or as a
treatment prior to surgery or
radiation
Induction
Initiation of chemotherapy with
plans for further treatments
Combination
Use of two or more chemotherapy
drugs together
the most common organ targeted in this type of chemotherapy, although it is also effective in certain brain cancers. Its use in head and neck cancers remains controversial. Further use of this type of chemotherapy is being investigated.
A catheter is inserted using radiologic techniques or surgery. Surgical insertion is the most common. Although it is less costly and less stressful, radiologic insertion results in a catheter that cannot stay in place as long as one inserted surgically. A radiologically inserted catheter stays in place for weeks compared to surgically inserted catheters designed to stay in place from weeks to years. In the long run, the surgically implanted arterial catheter has fewer complications, such as thrombosis or infection, and is more highly acceptable to the patient.
The radiologically placed catheter is initially inserted into an artery in the person's arm or leg, and then it is guided to its final destination near the tumor, where it can remain for an extended period.
The catheters require meticulous care to keep them clean and securely in place, which lessen the chance of complications. Problems associated with catheters include movement of the tip, blood clots and infection.
Pumps may be used to move the drug through the artery and into the tumor. A pump may be external or internally planted. External pumps range from large machines found in hospitals to portable wallet-sized devices. Implanted pumps give patients greater freedom, and are safe and effective. Some internal pumps deliver a constant flow of drugs, while others are programmed to deliver intermittent doses.
Drugs used for intra-arterial chemotherapy include FUDR (floxuridine), FU (fluorouracil), mitomycin, cisplatin, and streptomycin. Less frequently, doxorubicin has been used intra-arterially for treating certain cancers of the breast, bladder, stomach, and other areas.
Intralesional
Intralesional chemotherapy is the injection of anti-cancer drugs directly into a tumor that is in the skin, under the skin, or in an organ inside the body. Some examples involving the use of intralesional chemotherapy include melanoma and Kaposi's sarcoma. This type of chemotherapy shows promise for other malignancies such as laryngeal cancers, and further uses are under investigation.
Intraperitoneal
Intraperitoneal (IP) chemotherapy is administered into the abdominal cavity through a catheter or port that is put into place by surgery.
Ovarian cancer is sometimes treated with IP chemotherapy because this type of cancer usually stays within a confined area. This type of therapy is only suitable for some patients. Ovarian cancer patients whose tumors have a diameter greater than two centimeters may not receive this therapy because the anticancer drug does not reach very far into the tumor. Also, patients whose cancers are resistant to certain drugs may not undergo IP therapy. Patients with smaller tumors, or those who show response to chemotherapy are better candidates.
Intrathecal chemotherapy is the injection of anti-cancer drugs into the spinal fluid. This method is used primarily in treating acute lymphocytic leukemia. It is effective in placing the anticancer drug directly into the cerebrospinal fluid that surrounds the spinal cord and the brain. A spinal tap, also called lumbar puncture, is the procedure usually used to gain access to the spinal fluid. If many treatments are needed, a device called an Ommaya reservoir may be used. This device is inserted under the scalp and allows injection of anticancer drugs throughout the spinal fluid via the reservoir. Patients can go home with the Ommaya reservoir in place. Common drugs used intrathecally include methotrexate and cytarabine, which are usually given by a doctor with a nurse's assistance. Some leukemia patients receive IV treatments at the same time they are having intrathecal treatments.
Topical chemotherapy
Topical chemotherapy is given as a cream or ointment applied directly to the cancer. This method is more common in the treatment of certain types of skin cancer. An example is fluorouracil, also known as 5-FU, which is a topical anticancer cream.
Chemotherapy drugs
More than 50 chemotherapy drugs are currently available to treat cancer and many more are being tested for their ability to destroy cancer cells. About 30% of anticancer drugs come from or are derived from natural sources. Most chemotherapy drugs interfere with the cell's ability to grow or multiply. Although these drugs affect all cells in the body, many useful treatments are most effective against rapidly growing cells. Cancer cells grow more quickly than most other body cells. Other cells that grow fast are cells of the bone marrow that produce blood cells, cells in the stomach and intestines, and cells of the hair follicles. Therefore, the most common side effects of chemotherapy are linked to their effects on other fast growing cells. Some tumor cells are resistant to drugs, making them more difficult to target.
Alkylating agents
Alkylating drugs kill cancer cells by directly attacking DNA, the genetic material of the genes. By attacking the DNA, the drug prevents the cell from forming new cells. Nitrogen mustards, which were the first nonhormonal chemicals with anticancer abilities, are alkylating drugs. Cyclophosphamide and Mustargen are two alkylating agents. Cyclophosphamide, the most common alkylating agent, is often used in combination with other drugs to treat breast cancer, lymphomas, and other tumors in both children and adults. Mustargen is part of the treatment for Hodgkin's disease.
Platinum drugs
Drugs containing platinum are useful in treating a number of malignant tumors. Examples of these drugs include cisplatin, carboplatin, and oxaliplatin. Cisplatin is more toxic than the other two, and it is subject to resistance by the cancerous tumors. In fact, it was cisplatin's high toxicity that prompted the discovery of the other two platinum drugs, which are less toxic and more effective. Carboplatin has been shown to cause less nausea and vomiting than cisplatin, and it has replaced cisplatin in many treatment regimes. New platinum drugs are being investigated.
Antimetabolites
Antimetabolites interfere with the production of DNA and keep cells from growing and multiplying. They are used to treat a variety of cancers including breast cancer, leukemia, lymphoma, colorectal cancer, head and neck cancer, osteogenic sarcoma, choriocarcinoma (a rare uterine cancer), and urothelial cancer. Some drug resistance has occurred with these types of drugs. Examples of antimetabolites are 5-fluorouracil (5-FU), Tegafur, and Uracil.
Antitumor antibiotics are made from natural substances such as fungi in the soil. They interfere with important cell functions, including production of DNA and cell proteins. Doxorubicin, daunorubicin, idarubicin, epirubicin, dactinomycin, and bleomycin belong to this group of chemotherapy drugs.
Topoisomerase inhibitors
Topoisomerase inhibitors are effective in treating a number of cancers. Topoisomerase is an enzyme necessary for the replication of DNA within the cell. The topoisomerase inhibitors act on this enzyme, and the cell eventually dies. Drugs in this class include etoposide and teniposide.
Camptothecin analogues are also classed as topoisomerase inhibitors. Specific drugs are topotecan and irinotecan.
Anthracyclines are topoisomerase inhibitors such as daunorubicin, doxorubicin, epirubicin, and idarubicin. A drawback of the anthracyclines is their toxicity to the heart. Because of this, there have been efforts to develop synthetic drugs similar to the anthracyclines. Mitoxantrone and losoxantrone are two examples of synthetics.
Dactinomycin is another drug acting on the DNA of the cell. It is an effective drug for treating a variety of cancers including Ewing's sarcoma, Wilms' tumor, embryonal rhabdomyosarcoma, and gestational choriocarcinoma
(rare uterine cancer). It has also been used to treat cancer of the testicles, lymphoma, and Kaposi's sarcoma.
Antimicrotubule Agents
A microtubule is an important part of a cell, and is the target of a class of anticancer drugs.
Vinca alkaloids, which attack the cell's micro-tubules, are found in very small amounts in the periwinkle plant. Three types of vinca alkaloids are vincristine, vinblastine and vinorelbine. Vincristine is used more frequently in treating childhood, rather than adult, cancers. It is used in combination chemotherapy for the treatment of acute lymphocytic leukemia and Hodgkin's and non-Hodgkin's lymphoma, as well as other cancers. Vinblastine is used in combination chemotherapy for Kaposi's sarcoma, as well as cancers of the bladder, brain and breast. It is also used in the treatment of advanced cases of lymphoma and germ cell cancers.
The taxanes are another group of antimicrotubule agents. They are from the Pacific yew tree, and were first isolated in 1963. In 1971, paclitaxel was found to be an active ingredient in the bark of this tree. Paclitaxel has shown promising results in people with cancers of the ovaries or breasts. It is also used for AIDS patients who have Kaposi's sarcoma, and in combination with cisplatin in the treatment of non-small cell lung cancer. Paclitaxel is also part of the chemotherapy treatment in breast cancer patients whose cancer has spread to the lymph nodes. A related drug, docetaxel is used for treating advanced cases of breast cancer as well as certain non-small cell lung cancers.
Estramustine phosphate is related to nitrogen mustard. This drug acts on the microtubule of the cell, and has been effective in treating certain prostate cancers.
Hormones
Steroid hormones slow the growth of some cancers that depend on hormones. For example, tamoxifen is used to treat breast cancers that depend on the hormone estrogen for growth. Additionally, androgen suppression therapy is used in the treatment of prostate cancer. The goal of this therapy is to lower the levels of male hormones (androgens), especially testosterone, that can cause prostate cancer cells to grow. Lutenizing hormone-releasing hormone (LHRH) analogs lower testosterone levels by decreasing the androgens produced by the testicles. Two LHRH analogs available in the U.S. in 2001 are leuprolide acetate and goserelin.
Treatment location and schedule
Patients may take chemotherapy at home, in the doctor's office, or as an inpatient or outpatient at the hospital. Most patients stay in the hospital when first beginning chemotherapy, so their doctor can check for any side effects and change the dose if needed. A very important part of chemotherapy is determining the appropriate dose. To do this, the doctor must consider the person's size as well as any toxic side effects the drug may have.
How often and how long chemotherapy is given depends on the type of cancer, how patients respond to the drugs, patients' health and ability to tolerate the drugs, and on the types of drugs given. Chemotherapy administration may take only a few minutes or may last as long as several hours. Chemotherapy may be given daily, weekly, or monthly. A rest period may follow a course of treatment before the next course begins. In combination chemotherapy, more than one drug may be given at a time, or they may be given alternately, one following the other.
Precautions
There are many different types of chemotherapy drugs. Oncologists, doctors who specialize in treating cancer, determine which drugs are best suited for each patient. This decision is based on the type of cancer, the patient's age and health, and other drugs the patient is taking. Some patients should not be treated with certain chemotherapy drugs. Age and other conditions may affect the drugs with which a person may be treated. Heart disease, kidney disease, and diabetes are conditions that may limit the choice of treatment drugs. Pregnancy is another precaution because of the anticancer drug's impact on fetal development.
Preparation
A number of medical tests are done before chemotherapy is started. The oncologist will determine how much the cancer has spread from the results of x rays and other imaging tests and from samples of the tumor taken during surgery.
A patient's complete medical history will be taken, including any past chemotherapy. The patient will be asked to sign a consent form, and will be told about the drugs and procedures involved with chemotherapy. It is essential that the patient understand both the risks and benefits of treatment.
The nurse explains what will take place during the treatment, and what side effects to expect. In addition to the physical side effects, the stress of chemotherapy will be discussed. Patients who are better prepared tend to have fewer side effects and a higher emotional ability to handle the chemotherapy treatments.
Blood tests give the doctor important information about the function of the blood cells and levels of chemicals
in the blood. A complete blood count (CBC) is commonly done before and regularly during treatment. The CBC shows the numbers of white blood cells, red blood cells, and platelets in the blood. Because chemotherapy affects the bone marrow, where blood cells are made, levels of these cells often drop during chemotherapy. The white blood cells and platelets are most likely to be affected by chemotherapy. A drop in the white blood cell count means that the immune system cannot function properly. Low levels of platelets can cause a patient to bleed easily from a cut or other wound. A low red blood cell count can lead to anemia (deficiency of red blood cells) and fatigue.
When a chemotherapy treatment takes a long time, the patient may prepare for it by wearing comfortable clothes. Bringing a book to read or a tape to listen to may help pass the time and ease the stress of receiving chemotherapy. Some patients bring a friend or family member to provide company and support during treatment.
Sometimes, patients taking chemotherapy drugs known to cause nausea are given medications called anti-emetics before chemotherapy is administered. Anti-emetic drugs help to lessen feelings of nausea. Two anti-nausea medications that may be used are Kytril and Zofran.
Other ways to prepare for chemotherapy and help lessen nausea are:
Regularly eat nutritious foods and drink lots of fluids.
Eat and drink normally until about two hours before chemotherapy.
Eat high carbohydrate, low-fat foods and avoid spicy foods.
Aftercare
To control side effects after chemotherapy, patients should:
Follow any instructions given by the doctor or nurse.
Take all prescribed medications.
Eat small amounts of bland foods.
Drink lots of fluids.
Get plenty of rest.
Some patients find it helps to breathe fresh air or get mild exercise, such as taking a walk.
Risks
Chemotherapy drugs are toxic to normal cells as well as cancer cells. A dose that will destroy cancer cells will probably cause damage to some normal cells. Doctors adjust doses to do the least amount of harm possible
to normal cells. Some patients feel few or no side effects, and others may have more serious side effects. In some cases, a dose adjustment is all that is needed to reduce or stop a side effect.
A person may experience a side effect right away or the reaction may be delayed. Side effects are classified as follows:
acute, develops within 24 hours of treatment
delayed, develops after 24 hours but within six to eight weeks of treatment
short-term, combination of acute and delayed
late/long-term, develops months or years after treatment, or lasts for an extended period of time
expected, a side effect that develops in three quarters of patients
common, occurs in 25-75% of patients
uncommon/occasional, occurs in less than a quarter of patients
rare, occurs in 5% of patients
very rare, occurs in less than 1% of patients
Certain chemotherapy drugs have more side effects than others. While some drugs have immediate effects, other effects are delayed. Patients are encouraged to discuss the potential for side effects with their doctor. They must seek immediate medical attention if they are experiencing any unusual symptoms. Some of the most common side effects are discussed in this section.
Some chemotherapy drugs cause hair loss (alopecia), but it is almost always temporary. Hair re-growth may not begin until several weeks have passed since the final treatment. This is the most common impact that chemotherapy has on the outer surfaces of the body. In some patients, an ice wrap, called an ice turban, can reduce hair loss. The effectiveness will depend on factors such as the type of drug, dose, and treatment schedule. This preventive treatment must be avoided by patients with leukemia, lymphoma, mycosis fungoides or by those with scalp tumors. People should use with caution if they have conditions such as vasculitis, cryoglobulinemia or a history of radiation to the head. Patients should discuss the ice turban treatment with their doctor before trying it.
Anemia and fatigue
Low blood cell counts caused by the effect of chemotherapy on the bone marrow can lead to anemia, infections, and easy bleeding and bruising. Patients with anemia have too few red blood cells to deliver oxygen and nutrients to the body's tissues. Anemic patients feel tired and weak. If red blood cell levels fall too low, a blood transfusion may be given.
Infections
Patients receiving chemotherapy are more likely to get infections. This happens because their infection-fighting white blood cells are reduced. The level of reduction can vary depending on the dose and schedule of treatments, and whether the drug is used alone or in combination with other anticancer agents.
It is important for chemotherapy patients to avoid infection. When the white blood cell count drops too low, the doctor may prescribe medications called colony stimulating factors that help white blood cells grow. Neupogen and Leukine are two colony stimulants used as treatments to help fight infection.
Easy bleeding and bruising
Platelets are blood cells that make the blood clot. When patients do not have enough platelets, they may bleed or bruise easily, even from small injuries. Patients with low blood platelets should take precautions to avoid injuries. Medicines such as aspirin and other pain relievers can affect platelets and slow down the clotting process.
Sores in the mouth
Chemotherapy can cause irritation and dryness in the mouth and throat. An inflammation in the mouth is called stomatitis. Painful sores may form that can bleed and become infected. Precautions to avoid this side effect include getting dental care before chemotherapy begins, brushing the teeth and gums regularly with a soft brush, and avoiding mouth washes that contain salt or alcohol. Good oral hygiene is important. It is helpful for some patients to chew on ice chips for half an hour during chemotherapy treatments, but this should be discussed with the doctor before it is done.
Neuropathy and other damage to the nervous system
Cancer patients may develop neurological problems due to the cancer or the anticancer drugs. A variety of problems can develop, including altered mental alertness, changes in taste and smell, seizures, and peripheral neuropathy (tingling and burning sensations and/or weakness or numbness in the hands and/or feet). Different drugs can lead to different types of neurological disorders. Patients should discuss neurological symptoms with the doctor.
Heart damage
Some anticancer drugs are damaging to the heart. In these cases, the dosage is closely monitored in an attempt
to avoid heart damage. Specific drugs that may be toxic to the heart include doxorubicin, daunorubicin, high doses of cyclophosphamide, and, in some cases, 5-FU. Patients experiencing chest pain or any cardiac symptoms should seek immediate medical help.
Kidney damage
A number of anticancer drugs can damage the kidney. Examples include high doses of methotrexate or 6-MP, as well as regular doses of L-asparaginase, cisplatin, mithramycin, streptozocin, and mitomycin C. Some kidney problems can be lessened by taking in adequate amounts of fluids. A secondary danger of kidney damage is that a less functional kidney can be more susceptible to further toxicity caused by other anticancer drugs that the patient is taking.
Respiratory problems
Cancer patients who have had radiation in the chest area are more susceptible to respiratory complications. Nitrosourea or bleomycin cause the most common type of respiratory toxicity, called pulmonary fibrosis. Patients should get immediate medical assistance if they have difficulty breathing.
Sexual function
Some drugs can lead to impaired sexual function. Alkylating agents and procarbazine may result in the absence of sperm in a man and the lack of menstruation in a woman. Patients of child-bearing age are usually told to refrain from conceiving while undergoing chemotherapy because of the defects it can cause in the fetus.
Vision problems
Some anticancer drugs can impact a person's vision. High doses of cyclophosphamide can cause blurred vision in children, while some alkylating agents can cause cataracts. Tamoxifen may be damaging to the retina, and cisplatin can damage the optic nerve. Conjunctivitis, commonly called pinkeye, is a treatable problem that occurs with many anticancer drugs.
Results
The main goal of chemotherapy is to cure cancer. Many cancers are cured by chemotherapy. The chemo-therapy treatment may be used in combination with surgery to keep a cancer from spreading to other parts of the body. Some widespread, fast-growing cancers are more difficult to treat. In these cases, chemotherapy may slow the growth of the cancer cells.
Doctors can tell if the chemotherapy is working by the results of medical tests. Physical examination, blood tests, and x rays are all used to check the effects of treatment on the cancer.
The possible outcomes of chemotherapy are:
Complete remission or response. The cancer completely disappears for at least one month. The course of chemotherapy is completed and the patient is tested regularly for a recurrence.
Partial response. The cancer shrinks in size by at least 30-50%, the reduction in size is maintained for at least one month, and no new lesions are found during treatment. The same chemotherapy may be continued or a different combination of drugs may be used.
Minor response. The cancer shrinks 1-29%.
Stabilization. The cancer does not grow or shrink. Other therapy options may be explored. A tumor may stay stabilized for many years.
Progressive disease. The cancer continues to increase in size by at least 25%, or new lesions are noted. Other therapy options may be explored.
A secondary malignancy may develop from the one being treated, and that second cancer may need additional chemotherapy or other treatment.
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ORGANIZATION
American Cancer Society. 1599 Clifton Road, N.E., Atlanta, GA 30329. 1-800-ACS-2345.
Cancer Information Service of the National Cancer Institute. 1-800-4-CANCER.
OTHER
American Cancer Society. "How Will the Chemotherapy BeAdministered?" 28 May 2001. <http://www3.cancer.org>.
American Cancer Society. Laryngeal and Hypopharyngeal Cancer Resource Center. "How Are Laryngeal and Hypopharyngeal Cancers Treated?" 28 May 2001. <http://www3.cancer.org>.
—Treatment given after surgery or radiation therapy when there is no further evidence of cancer to prevent the cancer from coming back.
Alkaloid
—A type of chemical commonly found in plants and often having medicinal properties.
Alykylating drug
—A drug that kills cells by directly damaging DNA.
Antiemetic
—A medicine that helps control nausea; also called an anti-nausea drug.
Antimetabolite
—A drug that interferes with a cell's growth or ability to multiply.
Combination chemotherapy
—The use of two or more anticancer drugs over the same course of treatment.
Lumbar puncture
—A procedure in which a person lies on his or her side and a doctor inserts a needle into the spinal column. It can be used to withdraw spinal fluid or to deliver chemotherapy into the spinal fluid.
Peritoneal cavity
—The space between the two layers of the peritoneum, the membrane that covers the abdominal wall of the body.
