Abstract P2-08-24: Risk of chemotherapy-induced febrile neutropenia (FN) in patients with metastatic cancer of the breast or other sites not receiving colony-stimulating factor prophylaxis (CSF) in US clinical practice
Authors: Weycker Derek , Silvia Amanda , Hanau Ahuva , Lamerato Lois , Richert-Boe Kathryn , Kaur Manpreet , Shah Neel , Hatfield Mark , Lyman Gary H 
Published: March 2020

Abstract
Background: Clinical practice guidelines recommend CSF prophylaxis for patients receiving chemotherapy regimens with a high risk of FN (&gt;20%), and consideration of CSF prophylaxis for those receiving intermediate-risk regimens (10-20%) who have ≥1 risk factor for FN. The objective of this study was to estimate the use of CSF prophylaxis among patients with metastatic cancer, and the risk of FN among eligible patients not receiving it.
Methods: This retrospective study was conducted at four US health systems—Geisinger Health System (PA), Henry Ford Health System (MI), Kaiser Permanente Northwest (OR, WA), and Reliant Medical Group (MA). Study population comprised patients who received chemotherapy for metastatic solid tumors (breast, colon/rectum, lung) or non-Hodgkin’s lymphoma (NHL) from 2009-2017. For each eligible patient, data on chemotherapy course, cycles, and regimens, as well as the use of supportive care (CSF, antimicrobials) and FN episodes during the course, were collected via a standardized case report form using electronic data warehouses, cancer registries, and medical charts. Analyses were non-comparative and descriptive only.
Results: Study population totaled 1,457 patients (26% breast; 25% colon/rectum; 43% lung; 6% NHL). Nearly half of all patients received a chemotherapy regimen classified as either high-risk for FN (21%), or intermediate-risk for FN and had ≥1 FN risk factor (28%). Among patients receiving high-risk regimens, 51% did not receive primary prophylaxis with CSF (PP-CSF), and among those receiving an intermediate-risk regimen with ≥1 risk factor, 86% did not receive PP-CSF; among all remaining patients, 89% did not receive PP-CSF. Across these three subgroups of patients who did not receive PP-CSF (ie, high-risk regimen, intermediate-risk regimen with ≥1 risk factor, all others), FN risk during the course was 17%, 16%, and 14%, respectively. More than 90% of FN episodes required hospitalization, and FN-related mortality was 14%. Among metastatic breast cancer patients, 56% received a high-risk regimen (46%) or an intermediate-risk regimen and had ≥1 FN risk factor (10%); among this subset, 30% did not receive PP-CSF and their FN risk was 16%.
Conclusions: In this real-world evaluation of patients with metastatic cancer of the breast or other sites receiving chemotherapy at four large US health systems, over two-thirds of patients who were candidates for PP-CSF (per clinical guidelines) did not receive it. Among the subset of candidates who did not receive PP-CSF, FN risk was high (16%) and associated consequences were severe. Careful consideration should be given to identifying metastatic patients at elevated risk of FN—based on their chemotherapy regimen and risk factors—to ensure appropriate use of supportive care.
Table. FN risk factors and chemotherapy FN risk level among metastatic patientsBreast Cancer (N = 380)Colorectal Cancer (N = 360)Lung Cancer (N = 626)NHL (N = 91)All (N = 1,457)FN Risk FactorsAge ≥65y, %20.821.137.240.729.2Prior chemotherapy or radiation therapy, %39.234.248.445.142.3Prior neutropenia, %1.82.22.69.92.7Bone marrow involvement, %27.12.830.024.222.2Recent surgery, %40.042.216.914.329.0Liver dysfunction (bilirubin &gt;2.0), %0.81.40.50.00.8Renal dysfunction (creatinine clearance &lt;50), %45.362.259.365.956.8Chemotherapy FN Risk Level, %High45.80.017.417.620.5Intermediate10.554.726.450.530.7Low8.922.541.20.025.6Unclassified34.722.815.031.923.1
Citation Format: Derek Weycker, Amanda Silvia, Ahuva Hanau, Lois Lamerato, Kathryn Richert-Boe, Manpreet Kaur, Neel Shah, Mark Hatfield, Gary H Lyman. Risk of chemotherapy-induced febrile neutropenia (FN) in patients with metastatic cancer of the breast or other sites not receiving colony-stimulating factor prophylaxis (CSF) in US clinical practice [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-08-24.