Real-world use of G-CSF primary prophylaxis in small cell lung cancer: secondary data analysis from the French national cohorts KBP-2020-CPHG and ESCAP-2020-CPHG.

PURPOSE: Small-cell lung cancer (SCLC) is an aggressive malignancy frequently associated with chemotherapy-induced febrile neutropenia (FN), particularly with etoposide-platinum-based regimens. G-CSF primary prophylaxis (PP) is recommended according to regimen-level FN risk and patient-related risk factors. This study was aimed at describing the real-world use of G-CSF primary prophylaxis in patients with SCLC in France and at exploring survival outcomes descriptively. METHODS: This analysis used data from the prospective French national KBP-ESCAP-2020 cohorts, including patients newly diagnosed in 2020 and treated in non-academic public hospitals. Eligibility for G-CSF primary prophylaxis was determined according to chemotherapy regimen-level FN risk and patient-related risk factors based on guideline recommendations. RESULTS: Among 527 SCLC patients, 447 (84.8%) met the predefined eligibility criteria for G-CSF primary prophylaxis, of whom 285 (63.8%) received prophylaxis. G-CSF PP was more commonly administered to younger patients (mean age 66.4 vs. 69.4 years, p < 0.001) and those with a better PS (0-1 in 76.3% vs. 56.0%, p < 0.0001). In the sensitivity analysis, 439 patients remained eligible, of whom 281 (64.0%) received prophylaxis. Among patients eligible for G-CSF primary prophylaxis, median OS was 11.2 months [95% CI 10.2-12.0] with 3- and 6-month OS of 89.8% [86.4-93.4] and 75.4% [70.6-80.6] in the PP group, vs. 8.4 months [6.7-10.0], 72.8% [66.3-80.0], and 63.0% [55.9-70.9] in the non-PP group. PFS at 3 and 6 months was 86.7% [82.8-90.7] and 56.1% [50.7-62.2] vs. 70.4% [63.7-77.8] and 51.2% [44.1-59.5]. These estimates are descriptive, with baseline imbalances between groups and the associated survival curves cross at around 12 months. CONCLUSIONS: In this large real-world French cohort, G-CSF primary prophylaxis was administered to approximately two-thirds of patients meeting the predefined eligibility criteria, suggesting incomplete implementation of guideline recommendations. This proportion remained essentially unchanged in the sensitivity analysis.