Differential Diagnosis of Solitary Pulmonary Nodules in Postoperative Pancreatic Cancer Patients Using KRAS Gene Mutation Analysis.

Abstract

Solitary pulmonary nodules in postoperative pancreatic cancer patients pose a diagnostic challenge in distinguishing primary lung cancer (PLC) from pulmonary metastasis (PM). KRAS mutation analysis is a potential tool for distinguishing these entities. A retrospective study of 17 patients who underwent pulmonary resection after pancreatic cancer surgery was conducted. Paired pancreatic and pulmonary tumor samples were analyzed for KRAS mutations. PDX1 expression was assessed by immunohistochemistry. Preoperative clinical factors were evaluated using KRAS mutation-based classification as the reference. KRAS mutations were discordant between pancreatic and pulmonary tumors in nine patients (53%), leading to a diagnosis of PLC. KRAS G12R concordance was observed in three cases, confirming PM. Five cases with KRAS G12D or G12V concordance could not be definitively classified. KRAS mutation analysis identified more PLC cases than pathological diagnosis. PDX1 expression was found in both PM and some PLC cases, as well as in lung invasive mucinous adenocarcinoma cases without pancreatic cancer history, limiting its diagnostic value. Lymphovascular invasion in the pancreatic tumor was significantly associated with PM. KRAS mutation analysis of both pancreatic tumor and lung tumor is useful for distinguishing solitary pulmonary nodules in postoperative pancreatic cancer patients. KRAS mutation analysis identified PLC more frequently than conventional pathological diagnosis.