Dr Randall on Strengths vs Limitations of a Prospective Study of ctDNA in Osteosarcoma MRD Surveillance

"Detecting recurrence three months earlier is only meaningful if that earlier detection ultimately changes survival, quality of life, or treatment effectiveness, and that remains unproven."

R. Lor Randall, MD, FACS, the David Linn Endowed Chair for Orthopedic Surgery, chair of the Department of Orthopedic Surgery, and a professor at UC Davis Comprehensive Cancer Center, discussed the clinical implications of a landmark study investigating personalized circulating tumor DNA (ctDNA) panels for relapse detection in osteosarcoma.

This longitudinal, prospective study was designed to determine if molecular monitoring could identify recurrence earlier than conventional radiographic methods. The primary findings confirmed that post-operative ctDNA status serves as a statistically significant predictor of event-free survival (EFS), with negative results correlating with significantly improved patient outcomes (P < .05).

Randall identified several key strengths of the research, noting that it represents one of the largest tumor-informed ctDNA cohorts reported in osteosarcoma to date. He emphasized that the prospective longitudinal sampling strategy was a major highlight, as it allowed investigators to track specific molecular changes throughout the entire treatment and surveillance continuum. Furthermore, the study addressed clinically meaningful end points—relapse detection and EFS—supported by a strong biologic rationale. The personalized assay design is particularly well-suited to address the marked genomic heterogeneity that characterizes osteosarcoma.

However, Randall also acknowledged significant limitations that currently temper the technology's immediate clinical integration. The study was a relatively small, single-center investigation with a short median follow-up of just over 8 months. Critically, the sensitivity of the assay was not absolute; some patients experienced relapse despite having negative ctDNA tests, indicating that a negative result does not eliminate the risk of recurrence, he noted.

Ultimately, the most significant hurdle remains the distinction between prognostic value and clinical utility. Although the study proves that ctDNA can detect recurrence months earlier than imaging, Randall noted that it remains unproven whether acting on this earlier information improves patient survival, quality of life, or treatment effectiveness. He concluded that while the results are promising, this critical question must be answered before personalized panels can be fully integrated into standard practice.