Occult pT2–4 disease and postoperative loss of full-dose cisplatin eligibility in CT-staged cT≤1/cN0 upper tract urothelial carcinoma

PURPOSE: In upper tract urothelial carcinoma (UTUC), selecting candidates for perioperative chemotherapy is difficult because preoperative staging is inaccurate and nephro-ureterectomy lowers renal function. We assessed the frequency and prognosis of occult pT2-4 disease and the postoperative loss of full-dose cisplatin eligibility in radiographically non-locally advanced UTUC. METHODS: We retrospectively reviewed 280 surgically treated UTUC patients (1995-2024). The primary cohort comprised cM0/cN0/cT≤1 (CT-based) patients who underwent upfront radical nephro-ureterectomy without neoadjuvant therapy (n=173). The primary endpoint was occult pT2-4 disease; pN+ was descriptive. RESULTS: Occult pT2-4 disease occurred in 85 of 173 patients (49.1%) but declined across eras, reaching 23.8% in 2020-2024; pN+ was found in 4 of 32 lymphadenectomy-evaluable patients. Occult disease was associated with lower 5-year overall survival (58% vs 78%; adjusted hazard ratio 1.96, 95% CI 1.17-3.29). Among baseline full-dose-eligible occult-disease patients with postoperative data (n=27), 18 (66.7%) fell below the full-dose threshold and 1 (3.7%) became renally ineligible; this missed full-dose cisplatin window affected 18 of 173 patients (10.4%). CONCLUSION: Occult pT2-4 disease persisted in the contemporary era and was associated with worse overall survival although the pooled rate overstated current risk. Complete renal ineligibility was rare; the predominant change was a shift from the full-dose to the split-dose renal-function range. Because neoadjuvant chemotherapy was not evaluated, these findings indicate a need for better preoperative staging and prospective study rather than a treatment recommendation.