Sex- and Age-Related Differences in the Distribution of Metastases in Patients With Upper Urinary Tract Urothelial Carcinoma

Background: The distribution of metastatic sites in upper tract urothelial carcinoma (UTUC) is not well-known. Consequently, the effects of sex and age on the location of metastases is also unknown. This study sought to investigate age- and sex-related differences in the distribution of metastases in patients with UTUC. Materials and Methods: Within the Nationwide Inpatient Sample database (2000-2015), we identified 1,340 patients with metastatic UTUC. Sites of metastasis were assessed according to age (<= 63, 64-72, 73-79, and >= 80 years) and sex. Comparison was performed with trend and chi-square tests. Results: Of 1,340 patients with metastatic UTUC, 790 (59.0%) were men (median age, 71 years) and 550 (41.0%) were women (median age, 74 years). The lung was the most common site of metastases in men and women (28.2% and 26.4%, respectively), followed by bone in men (22.3% vs 18.0% of women) and liver in women (24.4% vs 20.5% of men). Increasing age was associated with decreasing rates of brain metastasis in men (from 6.5% to 2.9%; P = .03) and women (from 5.9% to 0.7%; P = .01). Moreover, increasing age in women, but not in men, was associated with decreasing rates of lung (from 33.3% to 24.3%; P = .02), lymph node (from 28.9% to 15.8%; P = .01), and bone metastases (from 22.2% to 10.5%; P = .02). Finally, rates of metastases in multiple organs did not vary with age or sex (65.2% in men vs 66.5% in women). Conclusions: Lung, bone, and liver metastases are the most common metastatic sites in both sexes. However, the distribution of metastases varies according to sex and age. These observations apply to everyday clinical practice and may be used, for example, to advocate for universal bone imaging in patients with UTUC. Moreover, our findings may also be used for design considerations of randomized trials.