About 650,000 cancer patients receive outpatient chemotherapy every year, according to the Centers for Disease Control and Prevention. Although chemo and radiation can extend cancer patients’ lives and help stamp out the disease, the treatments can put their lives at risk.

Chemo and radiation kill cancer cells, but they can also wipe out patients’ immunity. As a result, even seemingly benign infections can become threats to people being treated for cancer.

Up to 75 percent of our body’s white blood cells are neutrophils, and they play a major role in helping fight infection. When they’re needed, neutrophils are among the first cells to respond. They gobble up microorganisms and release enzymes and other substances to kill bacteria and stop infections in their tracks.

But chemotherapy and radiation can reduce the number of neutrophils in the blood and lead to a condition called neutropenia. Usually, patients are particularly susceptible between seven and 12 days after getting chemo. During this time, even minor infections can quickly become serious, leading to sepsis or death.

As a result, cancer patients who get one of the treatments should be extra careful. Frequent hand washing, glove use when gardening, regular bathing, fastidious food safety, and saying no to sharing food, utensils or cups with others are just a few ways to keep infection at bay.

Don’t have cancer or have a chemotherapy patient in your life? You can still help protect people with compromised immune systems by staying up to date on vaccinations such as the flu shot. Since people with weakened immune systems usually have to avoid live vaccines, they often must wait months to get routine vaccinations.

Meanwhile, their only protection is the community immunity that comes from others who are vaccinated.

Another easy way to help chemo patients is to wash your hands regularly and well. This helps stem the spread of disease and protect those whose immune systems can’t defend them against common infections.

The CDC offers a site for cancer patients, caregivers and health-care providers about infections and neutropenia. It’s at cdc.gov/cancer/preventinfections.