Doctor: McCain's setback 'normal' during brain cancer treatment

Sen. John McCain on Monday said he was "feeling well" in Arizona after being hospitalized last week in the Washington, D.C., area with a viral infection.

The six-term Republican, battling an aggressive form of brain cancer, was admitted last week to Walter Reed National Military Medical Center in Bethesda, Maryland. His office said that he received care for a viral infection that was described as "normal side effects of his ongoing cancer therapy." 

Doctors who are not involved in McCain's care said that a patient's energy levels can be sapped and immune system stressed while receiving radiation and chemotherapy treatment. That can make it difficult to shake viruses such as the common cold. 

"It is a fairly normal sign of a weakened immune system that is commonly seen in a patient who is undergoing radiation and chemotherapy," said Dr. Michael Lawton, president and CEO of Barrow Neurological Institute in Phoenix. 

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In July, McCain was diagnosed with glioblastoma, an aggressive and deadly form of brain cancer, after doctors removed a blood clot during a procedure at Mayo Clinic in Phoenix. He returned to Washington, D.C., and maintained his work schedule while he received radiation and chemotherapy treatment. 

Dr. Matthew Callister, a radiation oncologist at Banner MD Anderson Cancer Center in Gilbert, said a person's age and overall strength can be factors in how they handle treatment. However, an older adult who is relatively fit could fare better than a young adult who is not in the same physical condition.

"It depends a lot on the individual," Callister said. "The biggest issue is fatigue ... Treatment also can affect appetite and metabolism."

Dr. Mark Gilbert, chief of neuro-oncology at the National Institutes of Health's National Cancer Institute, said in a statement released by the senator's office that McCain responded well to treatment at Walter Reed for a viral infection.

Gilbert added that the senator's underlying cancer is "responding positively" to treatment.

In a Monday morning Twitter message, McCain thanked supporters for their warm wishes.

"I'm feeling well & looking forward to returning to work after the holidays," McCain tweeted.

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