Heterogeneity of metastatic pancreatic adenocarcinoma: Lung metastasis show better prognosis than liver metastasis—a case control study

The prognosis of metastatic pancreatic ductal adenocarcinoma (PDAC) is grim, with a median overall survival of under 1 year. In our clinical practice, we observed a few cases of isolated lung metastases from PDAC with unusually long outcomes. We compared these cases in a case-control study of lung-only vs. liver-only metastases from PDAC.From our database, we found 37 cases of lung-only metastases and paired them with 37 cases of liver-only metastases by age, tumor location and treatment.The lung-only group differed significantly from the liver-only group with respect to the following parameters: female predominance, more metachronous cases, fewer nodules per patient, and smaller increases in tumor markers. Local invasion parameters (i.e., arterial or venous involvement) were not significantly different. The outcomes were significantly different, with a median overall survival from the occurrence of metastases of 20.8 vs. 9.1 months and a median progression-free survival of 11 vs. 3.5 months.In conclusion, this case-control study seemed to confirm that lung-only PDAC metastases have prognoses different from those of liver-only metastases. A better understanding of the mechanisms underlying these differences will help identify abnormalities associated with tumor aggressiveness.