If someone's cell count is low but she's been healthy, is it still cause for worry?

This is the mystery of it: Almost every cancer patient experiences a drop in white count following chemotherapy (also after some types of radiation), but only a small percentage of patients experience serious infection. Getting sick as a result of low white blood cell counts depends on a host of factors, such as age, whether there's another condition affecting the immune system, which other medications she's taking, and her general state of health before the chemo. The doctor will likely say not to worry about a low white blood cell count unless the absolute neutrophil count, or ANC, drops into the high-risk category. Even then, the usual strategy is to simply become more vigilant in watching for signs of infection.