Treatment outcomes of ureteral stenting for malignant extrinsic ureteral obstruction: a comparison between polymeric and metallic stents

Jumpei Asakawa, Taro Iguchi, Satoshi Tamada, Noriko Ninomiya, Minoru Kato, Takeshi Yamasaki, Tatsuya Nakatani Department of Urology, Osaka City University Graduate School of Medicine, Osaka, Japan Purpose: To compare treatment outcomes, more specifically patency rate, of polymeric and metallic stents for malignant ureteral obstruction.Patients and methods: Between August 2007 and September 2017, we retrospectively analyzed the data of 92 patients (126 ureters) having a diagnosis of malignant extrinsic ureteral obstruction treated with indwelling ureteral stents (polymeric and full-length metallic stents). Of these patients, 35 (54 ureters) were treated with polymeric stents and 57 (72 ureters) with a Resonance® metallic stent. The observation period was censored to 1 year. Survival rate in cases of malignant ureteral obstruction was calculated, and the relationship between the causes of ureteral obstruction, the stent type, and the patency rate was evaluated.Results: The median observation period was 145 days, with a median survival time of 258 days. The stent patency rate was 70.9% at 1 year, regardless of stent type. Stent occlusion was observed in 20 patients (33 ureters). According to stent type, occlusion of the polymeric and metallic stents was identified in 12 (22%) and 8 (11%) cases, respectively. The clinical features associated with stent failure were assessed. In univariate analysis, the patency rate was significantly better for the metallic stent than for the polymeric stent (1-year patency rate; 78.4%, 61.1%, respectively, HR, 2.15; 95% CI, 1.07–4.33; p=0.031). However, the patency rate among patients with abdominal dissemination, lymph node metastasis, and direct compression by tumor was not significantly different.Conclusion: Indwelling ureteral stents, particularly metallic stents, are effective for the treatment of malignant ureteral obstruction. Keywords: metallic stent, malignant ureteral obstruction, polymeric stent