Genomic Concordance Between Primary and Oligo‐Recurrent Lesions in Pancreatobiliary Cancer

BACKGROUND/PURPOSE: The introduction of oligo-recurrence (OR) as a subtype of metastasis offered new hope, suggesting that local therapies may lead to prolonged survival/cure in selected cases. This study compared the genomic alterations between primary tumors and matched OR lesions in patients with pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA). METHODS: Eight patients with OR of PDAC or CCA were eligible. Genomic DNA was extracted from the tissue samples of primary tumors and matched OR lesions. Comprehensive genomic profiling (CGP) was performed using a panel of 216 cancer-related genes. The genomic profiles of the two groups were compared. RESULTS: Among 17 tumor samples from eight patients, 32 genomic mutations were identified in nine genes. A total of 48 copy number alterations were found across 31 distinct genes. Driver genomic mutations were concordant between the primary tumors and OR lesions in all cases, whereas differences in passenger mutations were observed in two cases. Five of the eight patients remained recurrence-free, including two pancreatic cancer cases who remained recurrence-free for > 4 years after surgery. CONCLUSIONS: The genomic mutation statuses of primary tumors and OR lesions were concordant, and patients' prognosis was significantly better than that of patients with other Stage IV cancers.