Metachronous pulmonary and pancreatic metastases arising from sigmoid colon cancer: A case report

BACKGROUND: Metachronous pulmonary and pancreatic metastases from colorectal cancer are rare. The diagnosis of pancreatic metastases is difficult and predominantly relies on computed tomography, pathology and immunohistochemistry. Here, we describe the use of next-generation sequencing (NGS) for determination of the origin of metastasis and prognostic prediction of colorectal cancer. CASE SUMMARY: A 59-year-old man was diagnosed with sigmoid adenocarcinoma stage IIA (T3N0M0) and underwent surgery in April 2014, followed by XELOX adjuvant chemotherapy. The patient developed pulmonary metastasis in the right upper lung and underwent surgery in May 2016 without further adjuvant chemotherapy. In May 2018, pancreatic metastasis was found and he underwent pancreaticoduodenectomy. After surgery, he was treated with adjuvant S-1 chemotherapy from June 2018 to March 2019. Histopathological review of the specimens from all three lesions indicated consistent patterns characteristic of colon cancer. Concordant gene mutation profiles were observed across the three lesions that included oncogenic driver mutations most frequently seen in colon cancer (e.g., APC, TP53, KRAS and FBXW7). Blood circulating tumor (ct)DNA before adjuvant chemotherapy was undetectable with NGS, suggesting a favorable response to chemotherapy. The patient was alive and well at the latest follow-up visit, achieving a disease-free survival of 17 mo. CONCLUSION: The genetic profiles of primary tumor, metastases and ctDNA may have clinical value in auxiliary diagnosis, prognosis and therapeutic decision-making.