What are infections and who is at risk?

When germs (also called microbes or microorganisms) enter the body, multiply, and cause harm or illness the result is an infection. The main types of germs are bacteria, viruses, protozoa (some of which act as parasites), and fungal organisms (also called fungi).

Infections that develop in people who have cancer or are getting cancer treatment can be more serious than those in people who are otherwise healthy. They can also be harder to treat. If you have cancer, it’s important to find and treat infections early, before they get worse and spread.

By learning more about problems that infections can cause, you and your family may be able to help prevent them:

• You can take steps to avoid being exposed to dangerous germs.
• You can take certain drugs and do things to help prevent some infections even after you have been exposed to the germs.
• If you do get an infection, the information here will help you know what to look for and what you should do to get treatment quickly.

Cancer itself can increase your risk of getting a serious infection. So can certain types of cancer treatment. Once the cancer is gone and treatment is over, the risk of infection usually goes back to a normal level.

For most people with cancer, the highest risk for serious infection only lasts for a limited time. And most people with cancer are not at a high risk of getting the kinds of infections described here. Your risk of infection depends on the type of cancer you have and the treatment you get. For example, surgery does not weaken a person’s resistance to infection nearly as much as a bone marrow transplant. And some chemotherapy drugs are less likely than others to affect a person’s ability to resist infection.

It’s important to weigh the risk of infection and other side effects against the benefits of cancer treatment. Talk with your doctors before or during chemotherapy or radiation therapy to see how this information applies to you. Here are some questions you can ask your doctor or cancer care team before and during cancer treatment:

• Will this cancer treatment make me more likely to get infections?
• If I get an infection, how severe is it likely to be, and how long might it last?
• Will you do anything special to help keep me from getting infections?
• What can I do to lower my risk of infection?
• How will I know if I have an infection?
• What should I do if I think I have an infection?
• If I get a fever, does that mean I have an infection?
• How will you decide how to treat my infection?
• What will you do if the treatment doesn’t get rid of my infection?
• What are the likely side effects of the proposed treatments for infection?