Influenza Can Cause Serious Complications in Cancer Patients, Survivors

Carrie A. Thompson, MD

The flu might just be an unwelcome nuisance for the average individual, but it can cause serious complications for cancer patients receiving treatment.

“While we know that patients who are on chemotherapy probably don’t mount the same immune response to the vaccine as healthy patients, there is still good evidence that getting the flu shot decreases the risk and the severity of influenza,” Carrie A. Thompson, MD, an assistant professor of medicine and a hematologist at the Mayo Clinic in Minnesota said in a phone interview. “The influenza virus is a significant problem in anyone whose immune system is compromised due to cancer treatment and can lead to complications like pneumonia or hospitalizations or treatment delays between chemotherapy cycles.”

Since cancer patients have a weakened immune system due to cancer treatment, it is important that they receive the flu shot, which is made up of inactivated viruses, instead of the nasal spray vaccine, which is made up of live viruses, she said

“It’s possible that if somebody is immune compromised, that a live virus can replicate and cause influenza,” Thompson said. “The flu shot is an inactivated vaccine, therefore it is not possible to get influenza through the flu shot.”

The American Cancer Society recommends that cancer patients and survivors receive the flu shot in October to give the body ample time to make antibodies against the disease.

While the Centers for Disease Control recommends that all cancer patients and survivors receive the flu shot, Thompson said patients with leukemia or those undergoing a bone marrow transplant are at the highest risk of catching the flu, due to the intensity of the therapies.

“But any cancer therapy can lower the immune system, which increases the risk of catching influenza,” she said.

Patients and oncologists should also work together to determine the best time to get the flu shot, especially when the patient is about to undergo chemotherapy or may be in the middle of chemotherapy treatment, Thompson said.

“If somebody is planning to get chemotherapy, we recommend to do the flu shot at least 2 weeks before starting,” she said.

If the patient has to undergo chemotherapy treatment right away or is already in the midst of chemotherapy treatment, Thompson recommends patients receive the flu shot in between chemotherapy cycles in order to try to mount the best response to the vaccine.

“Cancer patients are at increased risk of developing a secondary pneumonia after influenza, which can lead to significant complications,” she said. “If patients are on cancer treatment, getting a significant infection like influenza can really compromise the cancer care.”

When a cancer patient is undergoing treatment and gets sick, therapy may have to be stopped, Thompson said.

Caregivers and anyone who lives with a cancer patient should also receive a flu shot to minimize the risk of the cancer patient getting the flu, she said.

“We really try to do everything to keep people healthy so that we can continue the cancer treatment on schedule,” she said.

Since cancer survivors may also still retain a weakened immune system from prior cancer treatments, it is also recommended that they receive the flu shot, Thompson said.

“All cancer survivors should have an annual flu vaccine,” she said. “Given that they’ve had some sort of cancer treatment, it’s possible that their immune system may be a little weaker than other individuals.”

Thompson also recommends that cancer patients and survivors alert their oncologist if they are feeling any flu-like symptoms.

“If somebody does get the flu during the influenza season, there are antiviral treatments that can be used but it’s important that patients seek medical attention as soon as they develop symptoms because these treatments are most effective when they’re used early in the course of influenza,” she said.

All cancer patients and survivors should consult their oncologist before getting the flu shot, Thompson added.