Clinical features of glioma patients who develop pneumocystis pneumonia with temozolomide chemoradiotherapy.

Introduction: The treatment of glioma with temozolomide chemoradiotherapy predisposes patients to pneumocystis pneumonia (PCP). Because PCP is a rare outcome, very little is known about specific clinical risk factors for its development in patients with glioma.

Methods: We performed a population-based retrospective cohort study of glioma patients undergoing temozolomide chemoradiotherapy 2005 to 2019 in Ontario, Canada. We compared clinical features of patients who did not versus did develop PCP within one year of chemoradiotherapy. We examined the overall survival of patients by PCP status.

Results: There were 5130 patients with glioma treated with temozolomide chemoradiotherapy. Ultimately, 38 patients (0.74%) were diagnosed with PCP within 1 year of chemoradiotherapy. Most (71%) infections occurred between 0-90 days and 29% occurred between 91-365 days. Median survival was 12.3 months in patients who did not develop PCP and 8.6 months in those who did develop PCP (P < 0.001). Trough 90-day lymphocyte counts were lower in the PCP group. When the lymphocytes fell below 0.19 × 10/L (or 0.25 × 10/L among patients without PCP prophylaxis), the risk of PCP was > 3.5%.

Conclusions: Pneumocystis pneumonia is rare in glioma patients who receive temozolomide chemoradiotherapy. Infection is associated with shorter survival and the development of lymphopenia. Reserving PCP prophylaxis for patients whose lymphocyte counts drop below 0.25 × 10/L may be a reasonable strategy.