When a cancer patient is undergoing chemotherapy treatment, it almost always lowers his white blood cell count. Sometimes this happens only for a short period of time and the white blood cell count bounces back, other times it becomes an ongoing problem. Because white blood cells are the body's weapons against infection, having a low white blood cell count weakens the cancer patient's immune system. This means that when cancer patients catch a cold or flu, if their white count is low, they may not be able to fight off the infection as well as they normally would.
In this case, a cold or flu can quickly become more serious, leading to a high fever, pneumonia, or other complications. It's important for caregivers to understand the causes and symptoms of low white blood cell counts, so we've put together a longer article on the subject with more information.
When you're caring for a cancer patient and he catches a cold or flu, watch him closely for signs that the illness is becoming more serious. If his fever rises above 100 degrees or he develops a cough, chronic headache, or other symptoms of a bronchial or sinus infection, call his doctor. For more information on managing care for a patient with a low white blood cell count, see managing treatment for low white blood cell count.