Pneumocystis jiroveci pneumonia (PCP) in patients receiving neoadjuvant and adjuvant anthracycline-based chemotherapy for breast cancer: incidence and risk factors.

Opportunistic infection with Pneumocystis jiroveci pneumonia (PCP) has not been recognized as a significant complication of early-stage breast cancer treatment. However, we have observed an increase in PCP incidence among patients receiving chemotherapy for early-stage breast cancer. Herein we identify risk factors for and calculate incidence of PCP in this population. We identified all cases of PCP at Dana-Farber Cancer Institute/Brigham and Women's Hospital (DFCI/BWH) from 1/1/2000 to 12/31/2013 in patients with stage I-III breast cancer treated with an adriamycin/cyclophosphamide (AC)-containing regimen. Nineteen cases of PCP in non-metastatic breast cancer patients were identified. All patients with PCP were diagnosed after receipt of either three or four cycles of AC chemotherapy on a dose-dense schedule. Patients who developed PCP were treated with median 16.4 mg prednisone equivalents/day as nausea prophylaxis for a median 64 days. The overall incidence of PCP among 2057 patients treated with neoadjuvant or adjuvant dose-dense AC for three or more cycles was 0.6 % (95 % confidence interval 0.3-1.0 %). No PCP was diagnosed in 1001 patients treated with non-dose-dense AC. There was one death from PCP. Women receiving dose-dense AC chemotherapy for early-stage breast cancer are at risk for PCP. Administering the same chemotherapy and corticosteroid dose over an 8-week versus 12-week non-dose-dense schedule appears to have created a novel infectious vulnerability. Replacing dexamethasone with alternative anti-emetics may mitigate this risk.