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Chemotherapy and Your Immune System

Chemotherapy and Your Immune System

Coping with the High Risk of Infection Caused By Breast Cancer Treatment

If you receive chemotherapy treatments for breast cancer, you may face a high risk for developing infections, and your body may be less able to fight infections once they develop. This is because chemotherapy hurts your immune system by lowering the number of white blood cells produced in your body. White blood cells are important in preventing and fighting infections.

Chemotherapy and your immune system

Chemo tends to lower the number of white blood cells because it destroys any cells in your body that grow quickly. These include cancer cells, but also the rapidly growing healthy cells in your hair, digestive system, and bone marrow—where blood cells are produced.

It is important to remember that different types of chemotherapy affect the immune system differently and that individual responses to treatment can vary widely. You will have frequent blood tests during chemotherapy so that your doctor can monitor the levels of different blood cells in your body. Your white blood cell count may not go down significantly during chemotherapy. However, if it falls below a certain level, you will have a condition called neutropenia (pronounced: noo-tro-PEE-nee-ya). In this condition, your white blood cell level is extremely low and you are at a high risk for infection.

If your blood tests show that your white blood cell level is low, or that you have neutropenia, you will have to:

  • take special precautions to prevent infection
  • report any suspected infection to your doctor immediately
  • possibly receive injections of a substance that stimulates the growth of white blood cells

"...chemotherapy hurts your immune system by lowering the number of white blood cells produced in your body..."

Preventing Infection

There is nothing you can do to prevent your white blood cell count from dropping as a result of chemotherapy. What you can do is take extra-special precautions to avoid any situation that might increase your risk of infection. Because your immune system is weak, you can develop infections from bacteria that are always around but that normally do not affect you. Common areas for infection are your skin, mouth, digestive tract and genital areas. As a general rule, take extra care to keep these areas clean and to avoid injuring them.

Here are some specific ways to reduce your risk of infection:

  • Super Hygiene Maintenance
  • Wash your hands frequently.
  • Do not use antiperspirants or tampons.
  • Do not cut or pick at your cuticles.
  • Do not squeeze or scratch pimples.
  • Clean any cuts and scrapes immediately.
  • Protecting Vulnerable Areas
  • Always wear shoes.
  • Use gloves for dishwashing and gardening.
  • Use potholders when cooking.
  • Use sunscreen to avoid sunburn.
  • Use electric razors to avoid nicks.
  • Do not receive any vaccinations or have any dental work done without consulting your doctor.
  •  o protect your rectal area, do not use suppositories or enemas and do not take rectal temperatures.

Avoiding High Risk Situations

Stay away from people who are sick and from anyone who has been recently vaccinated.

Avoid crowds and public transportation.

Avoid anything that might have high concentrations of bacteria like standing water (birdbath, humidifier) and animal litter boxes.

Avoiding High Risk Activities

Do not do anything that’s likely to result in injury, like bicycling, skating, or skiing.

Avoiding Raw Foods

Do not eat raw fish, seafood, meat or eggs. Even raw fruits and vegetables and uncooked herbs can be risky.

Signs of Infection

If you have neutropenia, your doctor may ask you to take your temperature several times a day and report any changes. Even a small fever can indicate that you have an infection.

IMPORTANT REMINDER: If you have a fever, do not take any medicine (aspirin, ibuprofen, or anything else) to lower it. Your doctor will want to monitor your temperature to keep track of the infection.

Here is a list of the most common signs of infection. If you have any of them, call your doctor immediately:

  •  fever, chills or sweats
  •  cough, painful breathing or sore throat
  •  diarrhea
  •  mouth sores, or a change in the color of your gums
  •  pain or burning with urination or frequent need to urinate
  •  unusual vaginal discharge or itching
  •  redness, pain or swelling of any area of the skin
  •  redness, pain or swelling around cuts, sores, pimples, tubes or catheters


Boosting White Blood Cell Levels

If your white blood cell counts are low, your doctor may prescribe injections of a growth factor. Growth factors are substances that can stimulate the production of different cells in the body, such as white blood cells. By stimulating white blood cell production, growth factors strengthen your immune system and reduce your chance of getting an infection. You may receive growth factor injections from your doctor, or you can learn to inject them yourself. Your doctor may recommend that you start the injections before, during or after each course of chemotherapy.


References and Resources

Most of the information in this article was found on OncoLink, the Web site of the University of Pennsylvania’s Cancer Center. For more details visit

Other references include the web sites of the American Cancer Society and the National Cancer Institute.