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Potential side effects of chemotherapy for breast cancer
Side effects can occur with any type of treatment for breast cancer, but not everyone has them or experiences them in the same way. Side effects of chemotherapy will depend mainly on:
- the type of drug(s)
- the dose
- how the drug is given
- the woman’s overall health
Chemotherapy kills cancer cells, but it can also damage healthy cells. Different cells and tissues in the body tolerate chemotherapy differently.
Side effects can happen any time during chemotherapy. Some may happen during, immediately after, or a few days or weeks after chemotherapy. Most side effects go away after chemotherapy is completed, but it takes time for healthy cells to recover from the effects of chemotherapy drugs. Late side effects can occur months or years after chemotherapy. Some side effects may last a long time or be permanent.
It is important to report side effects to the healthcare team. Doctors may also grade (measure) how severe certain side effects are. Sometimes chemotherapy treatments need to be adjusted if side effects are severe.
Bone marrow suppression is a condition in which one or more of the main types of blood cells are decreased.
- A low white blood cell count (neutropenia) increases the risk of infection.
- A low platelet count (thrombocytopenia) increases the risk of bruising and bleeding.
- A low red blood cell count (anemia) causes fatigue, paleness and malaisemalaiseA general feeling of discomfort or illness..
Low blood cell counts occur because of chemotherapy’s effect on the blood cells made in the bone marrow. Blood cell counts often reach their lowest level about 7–14 days after the chemotherapy treatment has finished. Bone marrow suppression is the most common and most serious side effect of chemotherapy. When it happens, the dose of chemotherapy is usually adjusted or chemotherapy may have to be stopped temporarily.
Not all chemotherapy drugs used to treat breast cancer cause nausea and vomiting, but many do. Individual drugs vary in their effects, but nausea and vomiting are more likely when combinations of chemotherapy drugs are given.
Nausea and vomiting can occur within the first few hours after chemotherapy drugs are given and usually last about 24 hours. However, delayed nausea and vomiting may continue for a few days after treatment. Some women may have anticipatory nausea after having a few treatments, where they feel nauseated even before treatment is given because they expect to be sick.
Diarrhea is an increase in the number and looseness of stools. It occurs because chemotherapy drugs often affect the cells that line the gastrointestinalgastrointestinalReferring to or having to do with the digestive organs, particularly the stomach, small intestine and large intestine. tract. Many factors increase the risk of diarrhea, including the type and dose of chemotherapy drug used. Diarrhea is often worse when combinations of drugs are given. Diarrhea occurs soon after chemotherapy starts and can continue for up to 2 weeks after treatment has ended. It is a common side effect of the chemotherapy drugs used to treat breast cancer.
Constipation is a decrease in the normal number of bowel movements. The stools become hard, dry and difficult to pass. Many factors increase the risk of constipation, including the type of chemotherapy drug used, medications given with chemotherapy to relieve nausea and vomiting, and decreased fluid intake. Constipation usually occurs 3–7 days after the chemotherapy drug is given. Several chemotherapy drugs used to treat breast cancer can cause constipation.
Some women may gain weight during chemotherapy treatment for breast cancer. This is because eating small, frequent snacks helps relieve the feeling of mild nausea caused by some chemotherapy drugs. In addition, many women experience malaise, which can lead to eating more, and cannot exercise regularly during treatment. Together, these factors can lead to weigh gain during chemotherapy treatment.
Loss of appetite
Nausea and vomiting, fatigue or a buildup of waste products as cancer cells die can cause loss of appetite. Some chemotherapy drugs used to treat breast cancer can cause temporary changes in taste and smell, which can make foods seem less appetizing. Some women lose interest in food completely and don’t eat, even though they know they need to. This can lead to weight loss and malnutrition. Maintaining good nutrition during and after chemotherapy is important to help recover from treatment.
Women who receive chemotherapy for breast cancer tend to experience weight gain more often than loss of appetite.
A sore mouth (also called stomatitis or oral mucositis) occurs because of chemotherapy’s effect on cells inside the mouth. Many drugs used for breast cancer can cause a sore mouth. It occurs more often when higher doses of drugs are used. A sore mouth occurs about a week (5–14 days) after chemotherapy is started. It often improves on its own a few weeks after treatment is finished.
Painful mouth sores, ulcers in the mouth and mouth infections can also develop. Thorough, regular mouth care can help prevent a sore mouth and reduce infection. The healthcare team will give instructions about how often to clean and rinse the mouth and what to use. Pain medicines or special oral solutions may be needed to relieve pain.
Some of the chemotherapy drugs used to treat breast cancer turn the urine red for 1–2 days after the chemotherapy is given. This is not blood and is a normal side effect of these drugs. The urine may stain clothes if it comes in contact with them. Practise good hand-washing hygiene when using the washroom.
Hair loss (alopecia) is a common side effect of many, but not all, chemotherapy drugs that are used for breast cancer.
- The combination AC, which is doxorubicin (Adriamycin) and cyclophosphamide (Cytoxan, Procytox), almost always causes hair loss.
- The combination CMF, which is cyclophosphamide, methotrexate and 5-fluorouracil (Adrucil, 5-FU), may cause hair to thin but causes less hair loss than AC.
Hair follicles are sensitive to chemotherapy drugs because they grow fast. The extent and duration of hair loss is unpredictable. It depends on the type and dose of drugs used, as well as personal factors. Hair loss can occur on all parts of the body, including the face and scalp. Hair loss can begin 2 weeks after the first dose of chemotherapy. Hair usually grows back once chemotherapy treatments are over.
Hair should not be permed, straightened, dyed or coloured during treatment. These products contain chemicals that can damage hair. It is best to wait until new hair growth becomes established and hair returns to its original state. This may take as long as 6 months or more after treatment. Talk to the healthcare team about when you can use these products again.
Fatigue causes a woman to feel more tired than usual and can interfere with daily activities and sleep. It occurs for a variety of reasons. Fatigue may be caused by anemia, specific drugs, poor appetite or depression. It may also be related to toxic substances that are produced when cancer cells break down and die. Fatigue can occur days after a chemotherapy treatment cycle. It may get better as time goes by, but fatigue can continue long after the woman has finished her breast cancer treatment.
Muscle and joint pain
Some chemotherapy drugs given for breast cancer, especially paclitaxel (Taxol) and docetaxel (Taxotere), can cause pain or aching in the muscles and joints. This may continue for a period of time after the woman has finished treatment. The healthcare team may suggest a mild pain medication, such as acetaminophen (Tylenol), to help relieve the pain, along with rest. Light exercise may also help with muscle and joint pain.
Pain at the injection site
Many chemotherapy drugs are given by an injection, often intravenously (into a vein). After the initial needle stick to insert the intravenous (IV) needle or catheter, there is usually no discomfort or pain when IV chemotherapy drugs are given.
Sometimes chemotherapy drugs escape from the vein and leak into the surrounding tissues. This is called extravasation. When certain drugs leak into the tissues, they can cause blisters, redness, swelling, pain, burning or stinging at the injection site. These drugs are called vesicants. In some cases, extravasation of vesicants can cause severe damage to the skin and surrounding soft tissue.
Anthracyclines, which are used to treat breast cancer, are vesicants.
Skin and nail changes
Some chemotherapy drugs can cause minor skin changes or skin irritation. Skin changes can occur during and for some time after chemotherapy for breast cancer. They can include redness, itching, dryness or rash. Skin may be more sensitive or easily irritated by the sun during chemotherapy treatment.
Nail changes can include darkening, lines, cracking and splitting or brittle nails.
When certain drugs used in breast cancer chemotherapy are given, they can cause a skin reaction in an area that was treated with radiation. This is called radiation recall. The most common breast cancer drug to cause radiation recall is doxorubicin (Adriamycin), although other anthracyclines can cause it as well.
To prevent radiation recall, chemotherapy is usually given before radiation therapy.
Hand-foot syndrome (also known as palmar-plantar erythrodysesthesia or PPE) can be caused by several drugs used to treat breast cancer. Symptoms include redness, tenderness and peeling or scaling of the skin on the palms of the hands and the bottom of the feet. Tingling, pain or numbness can develop in the hands or feet.
Allergic reactions are not a common side effect of breast cancer chemotherapy, but they can happen. Although any drug can cause an allergic reaction, they are more likely to happen with paclitaxel or docetaxel.
Allergic reactions are most likely to occur shortly after the drug is given intravenously. Symptoms of an allergic reaction may include:
- difficulty breathing
- skin rash or hives
- severe allergic reaction (anaphylaxis)
Women being given these chemotherapy drugs are given medications before treatment starts to prevent an allergic reaction.
Chemotherapy drugs used to treat breast cancer in premenopausal women can damage the ovaries so they stop producing estrogen. This can cause treatment-induced menopause.
In younger women (under the age of 40), treatment-induced menopause may be temporary, though it may last for a period of time after chemotherapy is finished. In women over the age of 40, it is often permanent and leads to premature menopause.
Chemotherapy for breast cancer may lead to fertility problems in younger women. Periods may become irregular or stop temporarily during chemotherapy.
Not all chemotherapy drugs used for breast cancer will affect fertility. Shorter treatment with the chemotherapy combination AC may not affect fertility after breast cancer treatment is over. This chemotherapy may be offered for women who wish to preserve their fertility.
Chemotherapy does not necessarily prevent a woman from getting pregnant, so premenopausal women should talk to their healthcare team about appropriate birth control methods to use while receiving chemotherapy.
Changes to memory
A small number of women treated for breast cancer notice problems with memory and concentration. This is because chemotherapy can affect the way the brain functions. Sometimes this side effect is called “chemo-brain” or “mental fatigue.”
Nervous system damage
Some chemotherapy drugs used to treat breast cancer can cause peripheral nerve damage. This is particularly true for paclitaxel and vinorelbine (Navelbine). Nerve damage is often related to the dose of the chemotherapy drug given. Symptoms include tingling or numbness, trouble walking, muscle weakness and ringing in the ears or changes to hearing.
Most women experience temporary nervous system problems. In a few women, nervous system damage can become a long-term problem. Nervous system damage can develop months or years after treatment and may take months to go away.
Some chemotherapy drugs break down into substances that irritate the lining of the bladder when they are excreted in the urine. These substances can cause inflammationinflammationThe body’s protective response to injury or infection that includes redness, swelling, pain and warmth of the affected area. and bleeding. In rare cases, this irritation can become quite severe and lead to permanent bladder damage.
One chemotherapy drug used to treat breast cancer that can lead to bladder damage is cyclophosphamide (Cytoxan, Procytox).
Some chemotherapy drugs can damage the heart (cardiac) muscle. The chemotherapy drugs most commonly linked to changes in the heart muscle are the anthracycline drugs. The potential for heart damage (cardiotoxicity) varies with the type of chemotherapy drug.
The drugs used to treat breast cancer that are most likely to cause heart damage are doxorubicin or epirubicin (Pharmorubicin). Adding the biological therapy drug trastuzumab (Herceptin) can increase the risk of heart damage. If heart damage is suspected, the dose of the drug is decreased or the chemotherapy may have to be stopped to prevent further damage.
Symptoms may occur while the woman is receiving chemotherapy treatment for breast cancer. Sometimes the effects to the heart do not show up for weeks or months after chemotherapy is finished. Damage to the heart caused by doxorubicin or epirubicin can be permanent.
Only a very small percentage (less than 0.8%) of women develop a second cancer resulting from breast cancer treatments. The risk of developing a second cancer depends on the type and dose of chemotherapy drugs given and the length of treatment. The risk increases when:
- high doses of chemotherapy are used
- certain chemotherapy drugs are given, particularly anthracyclines
- treatment is given for a long period of time
Note: Other side effects may occur. For more detailed information on specific drugs, go to sources of drug information.
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