Effect of Pneumocystis jirovecii pneumonia prophylaxis on hematologic toxicity in patients receiving chemoradiation for primary brain tumors.

ABSTRACT

PURPOSE: Diffuse gliomas are managed with radiation and temozolomide; however, this therapy often results in hematologic toxicities. Patients undergoing chemoradiation also risk contracting Pneumocystis jirovecii pneumonia (PJP), and frequently receive prophylaxis against PJP during treatment. Independent of chemoradiation, some PJP prophylaxis drugs have the potential to cause myelosuppression, which could require cessation of chemotherapy. Here, we evaluate differences in the frequency of hematologic toxicities during chemoradiation when patients receive PJP prophylaxis. METHODS: This retrospective chart review evaluated patients with primary brain tumors treated with radiation and concurrent temozolomide. Analyses were performed to assess the effect of the type of PJP prophylaxis on risk for neutropenia, lymphopenia, or thrombocytopenia and the severity of these adverse effects as defined using the Common Terminology Criteria for Adverse Events. RESULTS: Of the 217 patients included in this analysis, 144 received trimethoprim-sulfamethoxazole (TMP/SMX) and 69 received pentamidine. Of the patients who received TMP/SMX, 15.3% developed an absolute neutrophil count < 1500 cells/µL compared with 7.2% of patients receiving pentamidine (p = 0.10). Platelet count < 100,000/µL occurred in 18.1% of patients who received TMP/SMX and 20.3% of patients who received pentamidine (p = 0.70). No significant differences in lymphocyte counts between therapies were seen. Severity of hematologic toxicities were similar between PJP prophylaxis groups. CONCLUSION: These findings suggest that the type of PJP prophylaxis does not significantly affect the risk for hematologic toxicity in brain tumor patients receiving radiation and temozolomide. Additional studies are merited to evaluate the higher rate of neutropenia in patients on TMP/SMX observed in this study.