Small cell lung cancer (SCLC) is a high-grade neuroendocrine carcinoma responsible for 200,000 deaths per year worldwide. Platinum-etoposide-based chemotherapy has been the standard of treatment for the past 40 years, with an overall survival of 10 months. Since 2019, the addition of immunotherapy (atezolizumab or durvalumab) to chemotherapy has become the standard of care for first-line treatment of extensive-stage SCLC following the demonstration of an improvement in overall survival in phase 3 studies. We aimed to evaluate the efficacy and safety of chemo-immunotherapy compared with chemotherapy alone in a “real-world” setting.

Retrospective observational study including patients undergoing first-line treatment for extensive-stage SCLC between 2014 and 2022. We separated the study population into two arms (chemo-immunotherapy/chemotherapy). For each arm, progression-free survival (PFS), overall survival (OS) and serious side effects were collected. Associations between treatments and survival outcomes were adjusted for potential confounders. Consolidative palliative thoracic radiotherapy was introduced in the models as a time-dependent variable.

A total of 118 patients with a median age of 63 years were included. 65.2 % of patients were performance status 0 or 1. In univariate analysis, PFS and OS were not significantly different between the chemo-immunotherapy and chemotherapy alone groups (p = 0.70 and 0.24 respectively). In multivariate analysis, the addition of immunotherapy to chemotherapy was not significantly associated with better PFS (HR 0.76, IC (0.49 – 1.19), p = 0.23), but it was significantly associated with better OS (HR 0.61, IC (0.38 – 0.98), p = 0.04). Consolidative palliative thoracic radiotherapy (time-dependent variable), when applied (almost only in the chemotherapy alone group), was significantly associated with better PFS and OS.

In this real-world study, chemo-immunotherapy was associated with slightly better OS compared to chemotherapy alone as a first-line treatment in ES-SCLC patients in multivariate analysis, which is not explained by a benefit in PFS. However, consolidative palliative thoracic radiotherapy seems to be significantly associated with better OS and PFS, suggesting that we should also consider using it in patients receiving chemo-immunotherapy.