A Highly Uncommon Presentation: A Consecutive Three-Case Series of Malignant Ureteral Obstruction in Long-Term Survivors of Non-small Cell Lung Cancer.

Malignant ureteral obstruction (MUO) is an exceptionally rare complication in non-small cell lung cancer (NSCLC), particularly among long-term survivors. We report three cases of MUO arising in patients with stage IV or recurrent NSCLC, all of whom had survived 3.6-4.0 years after their initial diagnosis. Two of the three cases harbored epidermal growth factor receptor (EGFR) mutations, and MUO in EGFR-mutated NSCLC has not been previously described, suggesting a potential association with prolonged survival under targeted therapy. All patients developed hydronephrosis and renal dysfunction requiring ureteral stent placement. Their clinical courses diverged: one EGFR-mutated patient maintained preserved renal function and remained free from urinary tract infection for three years and four months following stent placement, whereas the remaining two patients experienced rapid disease progression and died within months. These cases indicate that prompt recognition of MUO and early ureteral decompression may meaningfully improve symptoms and preserve renal function, thereby contributing to favorable clinical trajectories in selected long-term survivors. As patient survival continues to lengthen with modern systemic therapies, optimizing drainage strategies will become increasingly important.