A meta-analysis of circulating tumor DNA as a survival indicator in small cell lung cancer patients

A high level of circulating tumor DNA (ctDNA) has been linked to poor survival in patients with certain solid tumors. In spite of this, it is still unclear whether ctDNA is associated with poor survival in small cell lung cancer (SCLC). To investigate the above association, we conducted a systematic review and meta-analysis. PubMed, Web of Science, Cochrane's Library, and Embase were searched for relevant cohort studies from the inception of the databases to November 28, 2022. Data collection, literature search, and statistical analysis were carried out independently by two authors. To account for heterogeneity, we used a random-effects model. In this meta-analysis, 391 patients with SCLC were identified, and the data were pooled from nine observational studies and followed for 11.4 to 25.0 months. A high ctDNA was associated with worse overall survival (OS, risk ratio [RR] 2.50, 95% confidence interval [CI]1.85 to 3.38, p < 0.001; I² = 25%) and progression-free survival (PFS, RR 2.33, 95% CI 1.48 to 3.64, p < 0.001, I² = 42%). Subgroup analyses retrieved consistent results in prospective and retrospective studies, in studies with ctDNA measured with polymerase chain reaction or next-generation sequencing, and in studies analyzed with univariate or multivariate regression models. Studies suggest that ctDNA may be an important factor in predicting poor OS and PFS in SCLC patients.