Neutropenia is defined as an absolute neutrophil count (ANC) below 1500/mm3, with severe neutropenia below 500/mm3 and profound neutropenia below 100/mm3. ANC is calculated: ANC = WBC x (% segmented neutrophils + % bands) / 100. Neutrophils are the body's primary defense against bacterial and fungal infections. When ANC falls below 500/mm3, the risk of serious infection rises dramatically, and below 100/mm3, the risk is extremely high with potential for life-threatening sepsis within hours. Chemotherapy-induced neutropenia is the most common cause in oncology patients. The nadir (lowest ANC) typically occurs 7-14 days after chemotherapy, though this varies by agent. Febrile neutropenia is defined as a single oral temperature >=38.3C (101F) or sustained temperature >=38.0C (100.4F) for one hour in a patient with ANC <500/mm3 (or expected to decrease below 500 within 48 hours). This is a medical emergency requiring blood cultures and empiric broad-spectrum antibiotics within 60 minutes of presentation — delays in antibiotic administration increase mortality. The MASCC (Multinational Association for Supportive Care in Cancer) risk score stratifies patients into low-risk (outpatient management possible) and high-risk (inpatient IV antibiotics...