Synchronous Oligometastasis and Oligoprogression as a Prognostic Marker in Patients With Extensive-Stage SCLC Treated...

Oligometastasis and oligoprogression (OP) has not been adequately defined in extensive-stage SCLC (ES-SCLC) and may be a good indication for adding local treatment. Therefore, this multicenter study aimed to investigate the prognostic impact of oligometastasis and OP in ES-SCLC.

We enrolled patients who received chemoimmunotherapy between September 2019 and June 2022. Patients were classified into oligometastasis and non-oligometastasis groups by determining the number of original tumor lesions and distant metastases (worsening or newly appearing lesions) at the time of initial diagnosis and disease progression after first-line treatment.

We retrospectively analyzed 265 consecutive patients with ES-SCLC. Synchronous oligometastasis (SOM) and OP was defined as less than or equal to five lesions in less than or equal to two organs, including lungs; 21.0% and 53.2% of patients had SOM and OP, respectively. Median progression-free survival was 5.8 months and 4.9 months in patients with and without SOM, respectively (hazard ratio [HR] = 0.72, 95% confidence interval [CI]: 0.51-1.02, p = 0.065). Median overall survival was 20.5 months and 15.0 months in patients with and without SOM (HR = 0.58, 95% CI: 0.37-0.95, p = 0.027) from the initiation of first-line treatment. The OP group revealed a better progression-free survival of 5.2 months (versus 3.2 mo, HR = 0.69, 95% CI: 0.50-0.96, p = 0.026) and overall survival of 15.1 months (versus 7.5 mo, HR = 0.44, 95% CI: 0.29-0.66, p = 0.027) from the initiation of second-line treatment compared with the non-OP group. The Lung Immune Prognostic Index score was significantly lower in the SOM and OP group.

ES-SCLC in patients with SOM and OP may be more indolent than that of the nonoligometastasis group, therefore, new treatment strategies, including the addition of local treatment, should be explored.

This study was registered at UMIN-CTR (UMIN000053402).