Combining atezolizumab with carboplatin plus etoposide (Carbo-E) improved overall survival (OS) in patients with extensive-stage small cell lung cancer (ES-SCLC). However, there is a paucity of real-world outcomes. We present the largest and longest follow-up retrospective study evaluating treatment outcomes in ES-SCLC.

We conducted a retrospective cohort study to compare response rate, OS, and progression-free survival (PFS) in patients with ES-SCLC who received Carbo-E, Carbo-E and atezolizumab (Carbo-E-Atezo), and cisplatin and etoposide (Cis-E). We included all adult patients (≥ 18 years) treated at Cleveland Clinic between 1/2010-12/2022. Propensity score (PS) weighting and multivariable Cox proportional hazards regression adjusted for confounders.

Among 602 ES-SCLC patients, 375 (62 %) received Carbo-E, 160 (27 %) received Carbo-E-Atezo, and 67 (11 %) received Cis-E. The median age was 67, 65, and 59 years, respectively. The median follow-up among survivors was 23.9 months (IQR: 13.3---57.3). Five-year unadjusted OS was 4.5 % (Carbo-E), 7 % (Carbo-E-Atezo), and 5.2 % (Cis-E). Carbo-E-Atezo was associated with a longer PS-adjusted median OS than Carbo-E (9.1 vs. 8.2 months, P = 0.039), but no difference was seen in PFS (5.5 vs. 5.5, P = 0.09) or response rate (P > 0.9). Compared to Carbo-E, Cis-E showed higher response rates (OR: 1.67, P = 0.03) but no improvement in OS (11 vs 8.3 months, P = 0.067) or PFS (7.7 vs. 5.5 months, P = 0.058). Cis-E did not differ significantly from Carbo-E-Atezo in response rate, OS, or PFS.

Long-term outcomes in ES-SCLC remain poor. Atezolizumab added to Carbo-E modestly improved OS but not PFS. Cisplatin-based regimens increased response rates but did not improve survival.