The Impact of Ethnicity and Age on Distribution of Metastases in Patients with Upper Tract Urothelial Carcinoma: Analysis of SEER Data

Upper tract urothelial carcinoma (UTUC) constitutes a rare and aggressive entity accounting for 5% to 10% of all urothelial tumors. The importance of stratification and disparities according to ethnicity and age has never been tested in a sufficiently large sample of patients with metastatic UTUC (mUTUC). We conducted this study to address this void, and we hypothesized that the distribution of metastases may vary according to age and ethnicity. Within the Surveillance, Epidemiology, and End Results (SEER) database (2004-2016), we identified 1115 patients with mUTUC. The chi-square and t-test tests were used to examine statistical significance in terms of proportions and mean differences. A total of 925 (83.0%) patients were Caucasians, while 190 (17.0%) were African Americans. Among both ethnicities, lungs were the most common metastatic site (39.1% vs. 48.9%). Brain metastases were infrequent among both ethnicities (1.2 vs. 2.6%; p = 0.13). The trends in the lung metastases decreased with age from 42.3% to 36.6% (p = 0.010) among Caucasians, whereas they increased among African Americans from 34.0% to 51.7% (p = 0.04). Overall, 32.8% of Caucasians and 40.5% of African Americans exhibited more than one metastatic site. Among Caucasians, increasing age was associated with lower rates of having multiple metastatic sites (from 34.3% to 30.2%) (p = 0.004). According to our multivariable analyses, younger age was associated with an increased risk of lung (OR: 1.29, 95% CI 1.04-1.71; p = 0.045) and bone metastases (OR: 1.34, 95% CI 1.07-1.79; p = 0.046). Racial differences exist in the distribution of mUTUC metastasis and vary according to age. Our findings may also be considered in the design of randomized trials.