Pneumocystis Pneumonia in a Patient With Colorectal Cancer Receiving Bevacizumab and mFOLFOX6 Therapy

Pneumocystis pneumonia (PCP) can be a life-threatening fungal infection for immunocompromised individuals. We report a case of PCP in a 75-year-old male with colorectal cancer receiving bevacizumab plus mFOLFOX6 (oxaliplatin, leucovorin, and 5-fluorouracil) therapy.

The patient, diagnosed with unresectable advanced colorectal cancer, developed fever and neutropenia during the 40th course of bevacizumab plus mFOLFOX6 therapy and was diagnosed with febrile neutropenia. Moreover, laboratory tests and imaging studies indicated PCP. Although initial treatment with corticosteroids and trimethoprim-sulfamethoxazole temporarily improved the patient's condition, the patient later developed acute respiratory distress syndrome and succumbed to the disease. Lymphocytopenia associated with the prolonged bevacizumab plus mFOLFOX6 therapy may have contributed to the onset of PCP.

This case reaffirms that advanced age, immunosuppression, and cumulative steroid exposure are critical risk factors for PCP. Early imaging and prophylactic TMP-SMX administration should be considered in high-risk patients. Early intervention is crucial to prevent PCP progression to ARDS in patients with solid tumors.