Peritoneal Metastases in Stage II-III Colon Cancer Represent a Blind Spot for Circulating Tumor DNA Surveillance.

Ofori, Kwasi Ansere; Smart, Huxley; Liu, Sean; Bader, Justin M; Aguirre, Nicole; Gupta, Princy; Sharma, Anup; Turaga, Kiran · Ann Surg Oncol · 2026

prospective_cohort · Level II

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Abstract

While circulating tumor DNA (ctDNA) may guide adjuvant therapy in stage II-III colon cancer, detection largely hinges on systemic tumor shedding. In a secondary analysis of three prospective ctDNA studies, peritoneal metastases occurred in up to 9.4% of patients, were predominantly isolated, and were enriched among ctDNA-negative recurrences. Molecular and clinical data demonstrate reduced ctDNA levels in peritoneum-only disease, identifying a surveillance blind spot with direct implications for high-risk patients.