Leukopenia during cancer treatment is quite common, especially in chemotherapy patients. At the same time, leukopenia can also be caused by malignancies when infiltrating the bone marrow or by some malignancies that proliferate the lymphatic system, inhibiting the leukocyte flow. Furthermore, radiation therapy, if given to multiple sites of active bone marrow proliferation, can also cause leukopenia. Regardless of the cause, the risk of infection in people with leukopenia during cancer treatment is very high, which is a sign of severe prognosis.