Testing the external validity of the POUT III trial (adjuvant platnium-based chemotherapy in upper tract urothelial carcinoma) in a North American cohort.

Objective: The European POUT III randomized controlled trial provided level-one evidence that adjuvant platinum-based chemotherapy is the standard of care following nephroureterectomy (RNU) for locally invasive or node-positive upper tract urothelial carcinoma. We aim to assess this European randomized controlled trial's generalizability (external validity) to a North American cohort, using a nationwide database.

Materials And Methods: To compare trial patients with those seen in real-world practice, we simulated the trial inclusion criteria using data from the National Cancer Database (NCDB). We identified patients with histologically confirmed transitional cell carcinoma who underwent RNU. The available demographic characteristics of the NCDB cohort were compared with the POUT III trial cohort using Chi-squared test.

Results: The NCDB cohort (n = 3,380) had a significantly higher proportion of older patients (age ≥ 80: 23.5% vs. 5%), and more males (68% vs. 56.2%) than the POUT cohort (Table 1, both p < 0.001). Additionally, the rate of advanced nodal disease was higher in the NCDB (N1 9.6%, N2 9.3%) than in the POUT (N1 6%, N2 3%) cohort (p < 0.001). A more extensive lymph node dissection was performed in NCDB vs. POUT patients (node≥10 10.9% vs. 3%, p < 0.001). Sensitivity analysis removing all subjects with a Charlson Comorbidity Index > 0 did not change the significance of any results.

Conclusions: While the primary disease stage was similar, the rate of advanced nodal disease was significantly higher in NCDB, which might be explained partially by the more extensive lymph node dissection performed in the latter. These differences warrant caution when applying the POUT III findings to North American patients.