Relation between dexamethasone (DEX) usage, preventive trimetprim/sulfametoxazole (ST), and pneumocystis pneumonia (PCP) for patients with breast cancer receiving dose-dense AC followed by dose-dense paclitaxel (ddAC-ddP): Preplanned analysis of WJOG9016B.

Abstract

e12022 Background: PCP is rare complication of ddAC-ddP. DEX is plausible risk factor for PCP. Dose and duration of DEX against CINV is changing over time as other anti-emetic drugs (5HT3 RA, NK1 RA, and olanzapin) became available. Then DEX usage varies widely in each hospitals. ASCO/IDSA guideline recommends preventive ST for patients receiving 20 mg or more predonisone equivalents daily for more than one month, although evidence is lacking in patients receiving ddAC-ddP. This study is to investigate relation between DEX usage, preventive ST, and risk of PCP for patients receiving ddAC-ddP. Methods: This study is preplanned analysis of WJOG9016B (UMIN000024992) which investigated relative dose intensity of ddAC-ddP supported by 3.6 mg (approved dose in Japan) of pegfilgrastim. Eligible pts were HER2 negative PBC with stage I to IIIc, going to start ddAC-ddP and younger than 65 y.o.. DEX usage and preventive ST usage were discrete to treating physicians. Results: From Jan. 2017 to Jan. 2018, 92 pts were registered and 91 pts were in the FAS set, because one patients turned out be ineligible after registration. All patients received DEX for prevention of delayed CINV. Median total dose of DEX during ddAC was 112 mg (range; 80 to 212 mg), which was equal to 13.3 mg (9.52 mg–24.76 mg) predonisone equivalents daily. Only five of them (5.4%) received more than 20 mg predonisone equivalents daily. Twenty patients received preventive ST. Three patients developed PCP. None of them with preventive ST developed PCP (0%), whereas three of patients without ST developed PCP (4.2%). These three patients received total DEX dose during ddAC at 80 mg, 112 mg, and 112 mg, respectively. Conclusions: ST was highly effective for PCP prevention for patients receiving ddAC-ddP, if DEX used against delayed CINV. Without ST prevention, the risk of PCP was 4.2 %, which was higher than threshold (3.5%) proposed in ASCO/ IDSA guidelines. The threshold of steroid dose leading to the risk of PCP might be lower than 20 mg or more predonisone equivalents daily in patients receiving ddAC-ddP. Clinical trial information: UMIN000024992.