Causes of Fever After Chemotherapy in Patients with Malignant Lymphoma

Patients undergoing chemotherapy for malignant lymphoma may experience fever as a common side effect. While this symptom can be alarming, it often stems from specific physiological and pharmacological factors associated with cancer treatment. Understanding the underlying causes helps both patients and caregivers manage symptoms more effectively and seek timely medical intervention when necessary.

Decreased White Blood Cell Count and Immune Suppression

One of the primary reasons for post-chemotherapy fever is neutropenia—a significant drop in white blood cell (WBC) count, particularly neutrophils. Chemotherapeutic agents are cytotoxic by design, targeting rapidly dividing cells such as cancerous lymphocytes. However, they also affect healthy cells, especially those in the bone marrow responsible for producing blood components.

White blood cells play a crucial role in the body's immune defense, acting as the first line of protection against bacterial, viral, and fungal infections. When their levels fall due to chemotherapy, the immune system becomes compromised, leaving patients vulnerable to opportunistic pathogens. This condition, known as febrile neutropenia, is characterized by fever (typically defined as a single oral temperature of 38.3°C or higher) and requires immediate clinical evaluation to rule out life-threatening infections.

In many cases, prophylactic antibiotics and growth factor support (like G-CSF) are administered to reduce infection risk and accelerate WBC recovery. Close monitoring of blood counts throughout the treatment cycle is essential for early detection and management of immunosuppression-related complications.

Drug-Induced Fever (Drug Fever)

Besides infection-related causes, some patients develop fever directly due to the chemotherapy drugs themselves—a phenomenon referred to as drug fever. Certain agents, including cytarabine (Ara-C), are known to trigger transient inflammatory responses that manifest as fever without evidence of infection.

How Drug Fever Occurs

Drug-induced fever typically arises within hours or days after administration and resolves once the medication is discontinued. It's believed to result from the release of cytokines—signaling proteins involved in inflammation—in response to tumor cell breakdown or direct immune stimulation by the drug.

• Fever that correlates temporally with drug administration
• Absence of other identifiable infection sources
• Resolution of symptoms upon stopping the suspected agent
• Possible recurrence if the drug is reintroduced

Diagnosing drug fever involves a process of exclusion, requiring thorough lab testing and imaging to rule out infections or disease progression. Once confirmed, clinicians may adjust dosing schedules or switch to alternative regimens to minimize recurrence while maintaining therapeutic efficacy.

Other Contributing Factors

While low WBC counts and drug reactions are the most prevalent causes, additional factors can contribute to fever during lymphoma treatment:

Tumor lysis syndrome (TLS), although less common, can occur when large numbers of cancer cells die rapidly, releasing intracellular contents into the bloodstream. This metabolic disturbance may provoke systemic inflammation and fever, especially in patients with high tumor burden.

Additionally, central lines or catheters used for chemotherapy delivery can become sites for localized infection, leading to bloodstream infections and fever. Maintaining strict hygiene and regular assessment of vascular access points is critical in preventing such complications.

In rare instances, fever may also be a sign of underlying autoimmune phenomena or hypersensitivity reactions triggered by the combination of malignancy and treatment stress on the body.

When to Seek Medical Attention

Fever during chemotherapy should never be ignored. Any temperature elevation above 38°C warrants prompt contact with a healthcare provider. Early intervention improves outcomes, especially in immunocompromised individuals at high risk for sepsis.

Patients are generally advised to keep a thermometer at home, monitor symptoms daily, and maintain open communication with their oncology team. Signs like chills, fatigue, rash, cough, or pain should be reported immediately alongside fever.

In conclusion, while fever after chemotherapy for malignant lymphoma can stem from multiple sources—from suppressed immunity to drug side effects—timely recognition and appropriate management significantly improve patient safety and treatment continuity. With proper monitoring and supportive care, most febrile episodes can be addressed effectively without compromising long-term recovery goals.