Is it appropriate to select patients for primary prophylactic use of pegfilgrastim based on the risk of febrile neutropenia?

backgroundFebrile neutropenia (FN), a major hematologic adverse event in perioperative chemotherapy for breast cancer, is more prevalent among Asian populations than Caucasians. Hematopoietic growth factor guidelines recommend pegfilgrastim for primary prophylaxis based on chemotherapy regimen and patient risk factors. We verified the appropriateness of these guidelines for patient selection.

methodsThe CSPOR-BC FN study, a prospective multicenter study conducted in Japan from 2015 to 2017, included 477 patients surveyed for FN (≥ 37.5 ℃ and grade 4 neutropenia). Cutoff values for age and pre-treatment neutrophil count as risk factors were determined.

resultsThe incidence of FN was 28.7% (N = 137). The regimen (TC), age (≥ 65), low pre-treatment neutrophil count, and no primary prophylaxis with pegfilgrastim were significant FN risk factors. Logistic regression determined age ≥ 65 as a significant risk factor (odds ratio, OR = 2.24; 95% confidence interval, CI: 1.34-3.75). However, sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic (ROC) curve for FN cutoff at 65 were 28.4%, 83.8%, and 0.5195, respectively, indicating low discriminative ability. Similarly, pre-treatment neutrophil count at 1000/μl remained a risk factor (OR = 0.8, 95% CI: 0.67-0.95), even with the ROC-optimized cutoff of 2436/μl. The sensitivity, specificity, and AUC were 27.6%, 83.8%, and 0.5561, respectively, indicating a limited ability to differentiate.

conclusionThese results indicate that the current approach to select patients for primary prophylactic use of pegfilgrastim by evaluating existing FN risk factors may not be appropriate for individual patient assessment.