Pneumocystis jirovecii pneumonia in solid tumors: High mortality amid frequent corticosteroid exposure and infrequent prophylaxis

BACKGROUND: Pneumocystis jirovecii pneumonia (PCP) is increasingly recognized in non-HIV immunocompromised populations, including patients with solid tumors. However, the clinical characteristics, risk factors, and outcomes of PCP in this population remain poorly defined. OBJECTIVE: To characterize the clinical features, risk factors, and outcomes of PCP in patients with solid tumors and evaluate the role of corticosteroid exposure and prophylaxis. METHODS: We performed a retrospective cohort study of adults diagnosed with proven or probable PCP within a large integrated health system from January 1, 2017, through December 31, 2025. Patients with solid tumors were identified and compared with the remainder of the cohort. Multivariable logistic regression was used to evaluate factors associated with all-cause 30-day mortality and severe disease. RESULTS: Among 866 patients with PCP, 190 (21.9%) had solid tumors. Thirty-day and 90-day all-cause mortality were 37.9% and 48.4%, respectively. Chronic corticosteroid use was present in 54.7% of patients yet PCP prophylaxis was uncommon (3.2%). Metastatic disease (adjusted odds ratio [aOR]: 3.50; 95% CI, 1.40-8.76), chronic corticosteroid use (aOR: 2.60; 95% CI, 1.37-4.93), and lymphopenia (aOR: 2.40; 95% CI, 1.06-5.43) were independently associated with 30-day mortality. Compared with other PCP patients, those with solid tumors had higher odds of 30-day mortality (OR: 2.54 95% CI, 1.79-3.60) and severe disease (OR: 1.59; 95% CI, 1.15-2.20). CONCLUSIONS: Patients with solid tumors who develop PCP experience substantial morbidity and mortality. Corticosteroid exposure is common and frequently exceeds accepted prophylaxis thresholds, yet prophylaxis is rarely used, highlighting a potentially actionable gap in preventive care.