Side effects of treatment

It is hard to protect healthy cells from the harmful effects of breast cancer treatment. Because treatment does damage healthy cells and tissues, it causes side effects. The side effects of cancer treatment depend mainly on the type and extent of the treatment. Also, the effects may not be the same for each person, and they may be different from one treatment to the next. An important part of the treatment plan is the management of side effects.

A patient’s reaction to treatment is closely monitored by physical exams, blood tests, and other tests. Doctors and nurses will explain the possible side effects of treatment, and they can suggest ways to deal with problems that may occur during and after treatment. The NCI provides helpful, informative booklets about cancer treatments and coping with side effects. Patients may want to read “Understanding Breast Cancer Treatment: A Guide for Patients,“ as well as “Radiation Therapy and You,” “Chemotherapy and You,” and “Eating Hints for Cancer Patients.”


Surgery causes short-term pain and tenderness in the area of the operation, so women may need to talk with their doctor about pain management. Any kind of surgery also carries a risk of infection, poor wound healing, bleeding, or a reaction to the anesthesia used during surgery. Women who experience any of these problems should tell their doctor or nurse right away.

Removal of a breast can cause a woman’s weight to be out of balance – especially if she has large breasts. This imbalance can cause discomfort in her neck and back. Also, the skin in the area where the breast was removed may be tight, and the muscles of the arm and shoulder may feel stiff. After a mastectomy, some women have some permanent loss of strength in these muscles, but for most women, reduced strength and limited movement are temporary. The doctor, nurse, or physical therapist can recommend exercises to help a woman regain movement and strength in her arm and shoulder.

Because nerves may be injured or cut during surgery, a woman may have numbness and tingling in the chest, underarm, shoulder, and upper arm. These feelings usually go away within a few weeks or months, but some women have permanent numbness.

Removing the lymph nodes under the arm slows the flow of lymph. In some women, this fluid builds up in the arm and hand and causes swelling (lymphedema). Women need to protect the arm and hand on the treated side from injury or pressure, even long after surgery. They should ask the doctor how to handle any cuts, scratches, insect bites, or other injuries to the arm or hand. Also, they should contact the doctor if an infection develops in that arm or hand.

Radiation therapy

During radiation therapy, patients may become extremely tired, especially after several treatments. This feeling may continue for a while after treatment is over. Resting is important, but doctors usually advise their patients to try to stay reasonably active, matching their activities to their energy level. It is also common for the skin in the treated area to become red, dry, tender, and itchy. The breast may feel heavy and hard, but these conditions will clear up with time.

Toward the end of treatment, the skin may become moist and “weepy.” Exposing this area to air as much as possible will help the skin heal. Because bras and some types of clothing may rub the skin and cause irritation, patients may want to wear loose-fitting cotton clothes. Gentle skin care is important at this time, and patients should check with their doctor before using any deodorants, lotions, or creams on the treated area. These effects of radiation therapy on the skin are temporary, and the area gradually heals once treatment is over. However, there may be a permanent change in the color of the skin.


As with radiation, chemotherapy affects normal as well as cancer cells. The side effects of chemotherapy depend mainly on the specific drugs and the dose. In general, anticancer drugs affect rapidly dividing cells. These include blood cells, which fight infection, help the blood to clot, and carry oxygen to all parts of the body. When blood cells are affected, patients are more likely to get infections, may bruise or bleed easily, and may feel unusually weak and very tired. Rapidly dividing cells in hair roots and cells that line the digestive tract may also be affected. As a result, side effects may include loss of hair, poor appetite, nausea and vomiting, diarrhea, or mouth and lip sores. Many of these side effects can now be controlled, thanks to new or improved drugs. Side effects generally are short-term and gradually go away. Hair grows back, but it may be different in color and texture.

Some anticancer drugs can damage the ovaries. If the ovaries fail to produce hormones, the woman may have symptoms of menopause, such as hot flashes and vaginal dryness. Her periods may become irregular or may stop, and she may not be able to become pregnant. Other long-term side effects are quite rare, but there have been cases in which the heart is weakened, and second cancers such as leukemia (cancer of the blood cells) have occurred.

Women who are still menstruating may still be able to get pregnant during treatment. Because the effects of chemotherapy on an unborn child are not known, it is important for a woman to talk with her doctor about birth control before treatment begins. After treatment, some women regain their ability to become pregnant, but in women over the age of 35, infertility is likely to be permanent.

Hormonal therapy

The side effects of hormonal therapy depend largely on the specific drug or type of treatment. Tamoxifen is the most common hormonal treatment. This drug blocks the cancer cells’ use of estrogen but does not stop estrogen production. Tamoxifen may cause hot flashes, vaginal discharge or irritation, nausea, and irregular periods. Women who are still menstruating and having irregular periods may become pregnant more easily when taking tamoxifen. They should discuss birth control methods with their doctor.

Serious side effects of tamoxifen are rare. It can cause blood clots in the veins, especially in the legs and in the lungs, and in a small number of women, it can slightly increase the risk of stroke. Also, tamoxifen can cause cancer of the lining of the uterus. Any unusual vaginal bleeding should be reported to the doctor. The doctor may do a pelvic exam, as well as a biopsy of the lining of the uterus, or other tests. (This does not apply to women who have had a hysterectomy, surgery to remove the uterus.)

Young women whose ovaries are removed to deprive the cancer cells of estrogen experience menopause immediately. Their symptoms are likely to be more severe than symptoms associated with natural menopause.

Biological therapy

The side effects of biological therapy differ with the types of substances used, and from patient to patient. Rashes or swelling where the biological therapy is injected are common. Flu-like symptoms also may occur.

Herceptin may cause these and other side effects, but these effects generally become less severe after the first treatment. Less commonly, Herceptin can also cause damage to the heart that can lead to heart failure. It can also affect the lungs, causing breathing problems that require immediate medical attention. For these reasons, women are checked carefully for heart and lung problems before taking Herceptin. Patients who do take it are watched carefully during treatment.

Breast reconstruction

After a mastectomy, some women decide to wear a breast form (prosthesis). Others prefer to have breast reconstruction, either at the same time as the mastectomy or later on. Each option has its pros and cons, and what is right for one woman may not be right for another. What is important is that nearly every woman treated for breast cancer has choices. It is best to consult with a plastic surgeon before the mastectomy, even if reconstruction will be considered later on.

Various procedures are used to reconstruct the breast. Some use implants (either saline or silicone); others use tissue moved from another part of the woman’s body. The safety of silicone breast implants has been under review by the Food and Drug Administration (FDA) for several years. Women interested in having silicone implants should talk with their doctor about the FDA’s findings and the availability of silicone implants. Which type of reconstruction is best depends on a woman’s age, body type, and the type of surgery she had. A woman should ask the plastic surgeon to explain the risks and benefits of each type of reconstruction.

The National Cancer Institute booklet “Understanding Breast Cancer Treatment: A Guide for Patients” contains more information about breast reconstruction. The Cancer Information Service at 800-4-CANCER can suggest other sources of information about breast reconstruction and can talk with callers about breast cancer support groups.


Rehabilitation is a very important part of breast cancer treatment. The health care team makes every effort to help women return to their normal activities as soon as possible. Recovery will be different for each woman, depending on the extent of the disease, the type of treatment, and other factors.

Exercising the arm and shoulder after surgery can help a woman regain motion and strength in these areas. It can also reduce pain and stiffness in her neck and back. Carefully planned exercises should be started as soon as the doctor says the woman is ready, often within a day or so after surgery. Exercising begins slowly and gently and can even be done in bed. Gradually, exercising can be more active, and regular exercise becomes part of a woman’s normal routine. (Women who have a mastectomy and immediate breast reconstruction need special exercises, which the doctor or nurse will explain.)

Often, lymphedema after surgery can be prevented or reduced with certain exercises and by resting with the arm propped up on a pillow. If lymphedema occurs, the doctor may suggest exercises and other ways to deal with this problem. For example, some women with lymphedema wear an elastic sleeve or use an elastic cuff to improve lymph circulation. The doctor also may suggest other approaches, such as medication, manual lymph drainage (massage), or use of a machine that gently compresses the arm. The woman may be referred to a physical therapist or another specialist.

Followup care

Regular followup exams are important after breast cancer treatment. Regular checkups ensure that changes in health are noticed. Followup exams usually include examination of the breasts, chest, neck, and underarm areas, as well as periodic mammograms. If a woman has a breast implant, special mammogram techniques can be used. Sometimes the doctor may order other imaging procedures or lab tests.

A woman who has had cancer in one breast should report any changes in the treated area or in the other breast to her doctor right away. Because a woman who has had breast cancer is at risk of getting cancer in the other breast, mammograms are an important part of followup care.

Also, a woman who has had breast cancer should tell her doctor about other physical problems, such as pain, loss of appetite or weight, changes in menstrual cycles, unusual vaginal bleeding, or blurred vision. She should also report headaches, dizziness, shortness of breath, coughing or hoarseness, backaches, or digestive problems that seem unusual or that don’t go away. These symptoms may be a sign that the cancer has returned, but they can also be signs of various other problems. It’s important to share these concerns with a doctor.

National Cancer Institute (NCI)