Different approach to M descriptor for future staging of oligometastatic disease in SCLC: A cross-sectional survival analysis

Abstract

Purpose This study aimed to investigate the impact of oligometastasis and the M descriptor on survival in small cell lung cancer (SCLC). Methods This multicenter, retrospective study included patients with newly diagnosed extensive-stage SCLC(ES-SCLC) from 2010 to 2020. Subgroups: Group 1: single metastasis in a single organ, Group 2: 2-5 metastases in a single organ, Group 3: 6 or more metastases in a single organ, and Group 4: metastases in two or more organs. This classification was based on the 9th Staging-M descriptor. Three-year progression-free survival (PFS) and overall survival (OS) analyses were conducted. Results The mean age of the 439 patients was 62 +/- 10 years, and 89.5% of them were male. The mean PFS for Groups 1, 2, 3, 4 was 10.7 months (95% CI 8.9-12.5), 7.5 months (95% CI 5.6-9.4), 4.3 months (95% CI 2.9-5.7), and 5.4 months (95% CI 4.7-6.1), respectively. PFS in Group 2 was significantly higher. The mean OS for Groups 1, 2, 3, 4 was 13.3 months (95% CI 11.2-15.3), 9.5 months (95% CI 7.1-11.9), 7.1 months (95% CI 4.5-9.7), and 6.9 months (95% CI 6.0-7.9), respectively. OS in Group 1 was significantly higher. OS and PFS in the M1b group were significantly higher than in the M1c1 and M1c2 groups (p < 0.05) with no statistical difference between the M1c1 and M1c2 groups. Conclusion There is no significant difference in survival between the M1c1 and M1c2 groups. In ES-SCLC, the number of metastases may be a more predictive factor for prognosis than the number of metastatic organs.