OBJECTIVES: To report results of an epidemiology model estimating metastatic (stage IV) NSCLC patient population size in WE for first (1L) through second LOT (2L), including maintenance.

METHODS: Data were combined from cancer registries in WE (France, Germany, Italy, Spain, and the United Kingdom), IARC’s Cancer Incidence in Five Continents (volume XI), and physician survey results from CancerMPact^® (CMP). Recent country-, age-, and sex-specific incidences of NSCLC by histology were estimated and multiplied by respective projected country populations to estimate annual number of new cases for 2021-2026. Staging distribution (AJCC 8^th edition) of NSCLC by histology from SEER for 2018 was applied. 10-year prevalence was calculated for stage IV NSCLC patients by histology, combining incidence and survival data from SEER. The number of unique Stage IV NSCLC patients without driver mutations during a given year on 1L, 1L maintenance, or 2L were calculated using data from the 2020 CMP physician survey.

RESULTS: 10-year prevalence in WE of stage IV NSCLC patients without driver mutations was estimated at 182,550 in 2021 and projected to increase to 195,216 by 2026. The numbers of stage IV non-squamous (NSQ) NSCLC patients with active treatment by LOT in 2021 are estimated at 42,484 in 1L, 44,151 in 1L maintenance, and 24,517 in 2L. Corresponding estimates of SQ patient numbers are 13,446 in 1L, 8,363 for 1L maintenance, and 8,157 in 2L. The total increase in number of unique patients over 2021-2026 varied by country (NSQ [range]: 4.6%-9.5%; SQ: 3.9%-10.4%).

CONCLUSIONS: The number of patients receiving active treatment for SQ and NSQ metastatic NSCLC without driver mutations in WE is substantial and expected to increase in the future. The 5-year overall survival for stage IV NSCLC remains ~6%, suggesting that new treatments are needed. Robust estimates are critical to anticipate unmet needs by LOT.