Real-World Utilization and Performance of Circulating Tumor DNA Monitoring to Predict Recurrence in Solid Tumors

PURPOSE Circulating tumor DNA (ctDNA) is a novel biomarker to monitor treatment response and predict cancer recurrence. However, the real-world performance of ctDNA monitoring is not well characterized in underrepresented populations such as the Southeast Asians. METHODS This retrospective analysis included patients with cancer who had commercial ctDNA tests (K-Track, Gene Solutions, Vietnam) between August 2022 and December 2023. A personalized tumor-informed ctDNA assay was performed for 623 patients and 815 plasma samples to quantify ctDNA before and after treatment. Clinical data of minimum 6 months after the last ctDNA test were available for 263 early-stage patients to analyze the prognostic value of ctDNA. RESULTS In the early-stage I-III, preoperative ctDNA detection rates were 66.7%, 84.6%, 54.3%, 52.6%, 93.3%, and 75.0% for lung, colorectal, breast, gastric, liver, and ovarian cancers, respectively. After surgery, 84.4% (38/45) of patients with recurrence had ctDNA detected in the plasma, while 96.3% (210/218) of patients with no recurrence had negative results. Postoperative ctDNA positivity significantly increased the risk of recurrence ( P < .001) in lung (hazard ratio [HR], 71.3 [95% CI, 17.6 to 287.8]), colorectal (HR, 44.3 [95% CI, 11.3 to 173.2]), breast (HR, 37.6 [95% CI, 3.09 to 456.8]), and gastric (HR, >100 [95% CI, 26.9 to >100.0) cancers. In the metastatic stage IV, pretreatment ctDNA detection rates were 80.0%, 87.7%, 73.3%, 70.6%, 91.7%, and 81.8% for lung, colorectal, breast, gastric, liver, and ovarian cancers, respectively. Case studies were presented to demonstrate utilization of ctDNA at all cancer stages. CONCLUSION ctDNA was a strong prognostic biomarker to monitor patients during cancer management.