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Gastric and esophageal cancers (GECS) hold a significant impact on the amount of cancer diagnosis and deaths yearly. Throughout the last several years, researchers have evaluated the effectiveness of ctDNA to estimate tumor burden and characterizing the genomic landscape of tumor biology and response to therapy in the metastatic setting. The goal is to detect minimal residual disease (MRD) and monitor cancer surveillance in the locally advanced setting.Dr. Rutika Mehta

In a previous trial, researchers studied the role of a commercial ctDNA assay for MRD detection and surveillance in locally advanced GECS. At this year’s AACR conference, Dr. Rutika Mehta, medical oncologist at Moffitt’s Gastrointestinal Oncology Program presented findings when using the same ctDNA assay in advanced stage settings of GECs.

For this study, 53 cohorts with recurrent/metastatic esophageal cancer were analyzed. 216 samples of plasma samples were collected over the course of October 2008 to August of 2022. The patients were divided into 3 groups: Group A (N=30) included patients with stage II/III disease who had confirmed clinical recurrence (R). Group B included (N=25) included patients with recurrent and Stage IV esophageal cancer who achieved a state of no evidence of disease on imaging. Group C (N=5) included recurrent and stage IV patients who transiently achieved NED on imaging. This study included the use of a personalized, tumor-informed multiplex PCR-based next-generation sequencing assay (Signatera), used to quantify ctDNA either postoperatively, on adjuvant or palliative therapy, or during active surveillance.

The results presented 30 of the 53 patients with recurrent stage II/III esophageal cancer had ctDNA status available postoperatively within 150 days of confirmed clinical recurrence.

Group A: 25 patients were ctDNA-positive ahead of clinical recurrence (sensitivity 83.3%) with a median of 31 days (range: 1-147 days.)
Group B: Next, the researchers studied the correlation between ctDNA status and imaging. 24 of the 25 patients showed significant correlation between ctDNA status (positive or negative) and disease status by imaging (Fisher exact test p=0.0001). 17 patients were ctDNA-negative and showed NED on imaging (negative predictive value of 100%; 17/17).  
Group C: All of the patients in this cohort demonstrated recurrent disease on imaging following NED and were ctDNA-positive prior to imaging.

The findings of this study demonstrated the utility of ctDNA in accurately predicting disease progression and supports the potential use of ctDNA to inform treatment decisions or prompt early radiographic imaging. Ultimately, ctDNA may surpass traditional radiographic surveillance benefitting patient by being minimally invasive and cost-effective in monitoring patients during and post-treatment.

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