Neutropenic Sepsis
A life-threatening oncological emergency in which chemotherapy-induced collapse of the neutrophil count removes the main defence against bacteria, so a fever after chemotherapy is treated as sepsis and given broad-spectrum antibiotics within one hour, before the neutrophil count is even known.
First principles
Neutrophils are the first responders against bacteria, and cytotoxic chemotherapy destroys them selectively
Chemotherapy targets rapidly dividing cells, and bone marrow precursors divide as fast as the tumour it is aimed at. Neutrophils have the shortest lifespan of the marrow-derived cell lines, so they are the first and hardest hit, typically reaching their lowest point (nadir) seven to fourteen days after a cycle. Without neutrophils, bacteria (commonly gut flora that translocate across chemotherapy-damaged mucosa) proliferate with no first line of defence to stop them.
Educational content pending clinical review. Not medical advice.