Chemotherapy treatments for cancer are well known to be associated with a depletion of white blood cells, in particular neutrophils, causing a condition known as chemotherapy-induced neutropenia (CIN). Neutropenia is a serious adverse effect frequently associated with cancer chemotherapy. Loss of neutrophils causes disruption of immune defense mechanisms and increases the likelihood for infections.
The definition of neutropenia varies from institution to institution, but neutropenia is usually defined as an absolute neutrophil count (ANC) <1500 or 1000 cells/microL and severe neutropenia as an ANC <500 cells/microL or an ANC that is expected to decrease to <500 cells/microL over the next 48 hours.
Who Gets CIN?
CIN is a common side effect in cancer patients undergoing treatment that involves the destruction of a type of white blood cell (neutrophil), which is a patient’s first line of defense against infections. Patients with Grade 4 (severe) neutropenia have an abnormally low concentration of neutrophils, which may lead to infections, hospitalization and death.
G-CSFs are the current standard of care for CIN prevention. However, G-CSFs have limitations in reducing Grade 4 neutropenia with high-risk chemotherapy. Neutropenia, if severe enough, may cause doctors to lower target doses of chemotherapy, end therapy early and / or delay chemotherapy cycles, each of which has a negative effect on long-term outcomes of cancer care.
The incidences of CIN and its complications, such as fever, infection, and chemotherapy dose alterations, vary by type of malignancy. One large prospective registry reported CIN rates of 15% to 65% in patients with five major tumor types: breast cancer, colon cancer, lymphoma, lung cancer, and ovarian cancer.