Prognostic impact of oligometastasis in older patients with extensive-stage small cell lung cancer

Immune checkpoint inhibitor plus chemotherapy (ICT) is the standard treatment for extensive-stage small cell lung cancer (ES-SCLC). We previously reported that oligometastasis (OM) is a predictor of ICT efficacy, however, the relationship between ICT efficacy and OM in older patients remains unknown. Therefore, this study examined the efficacy of ICT in the older patients including the influence of OM.

We enrolled patients with ES-SCLC who received ICT as first-line treatment between September 2019 and June 2022. Patient characteristics and treatment efficacy were compared between older (≥75 years) and non-older (<75 years) patients.

We enrolled 228 patients, including 42 older patients. The prevalence of synchronous oligometastasis (SOM) at the start of first-line treatment was 21.0 % and 21.4 % (p = 1.0) in the older and non-older groups, respectively. The progression-free survival (PFS) with first-line therapy was 5.4 and 4.5 months (p = 0.55) and overall survival (OS) was 11.5 and 12.6 months (p = 0.74) for the SOM and non-SOM subgroups in the older group, respectively. For second-line treatment, PFS was 4.5 and 6.3 months (p = 0.79), and OS after second-line initiation was 16.0 and 13.2 months (p = 0.55) in oligoprogression (OP) and non-OP patients in the older group, respectively.

The frequencies of SOM and OP were not significantly different between older and non-older patients. Although the small number of older patients in this study makes it impossible to conclude definitively, we did not observe a significant prognostic prolongation in older patients with OM as in non-older patients.