Clinical utility of longitudinal ctDNA monitoring by multiplex MS-ddPCR for risk stratification and follow-up in rectal cancer

With this MS-ddPCR assay, preoperative ctDNA showed limited prognostic value, whereas ctDNA 6 months postoperatively was strongly associated with recurrence and overall survival. The absence of an immediate postoperative sample limited assessment of early molecular response-a time point critical for guiding treatment decisions and follow-up strategies-underscoring the need for earlier sampling in future studies to optimize ctDNA-guided management. Given the small cohort and exploratory design, these findings are hypothesis-generating and support further validation of the assay in larger, prospective trials.