PD13-09: Clinical validation of the EAU2021 intermediate risk NMIBC definition and implications for adjuvant treatment: a multicenter YAU Urothelial Collaboration
Department of Surgical Science, University of Studies of Torino
Introduction: Recently, EAU Guidelines adopted a new risk-stratification model for NMIBC (EAU2021 scoring model), which was tested in an IPD analysis of 3041 primary NMIBC. Of these, only 54% were treated with adjuvant chemotherapy and may be not representative of current clinical practice. Moreover, using the EAU2021 model, some TaHG tumors should be classified as intermediate risk (IR). Consequently, the IR group now includes a broad spectrum of disease (Ta and T1 as well as LG and HG tumors) for whom treatment may vary from adjuvant chemotherapy with or without maintenance to intravesical BCG.Based on these considerations, the outcome of our study was to validate the homogeneity of IR group and to evaluate the most effective chemotherapy regimen for each subgroup of patients. Methods: This was a multicenter collaboration involving 8 European referral Centers of the YAU Urothelial working group. Primary or recurrent NMIBC treated with intravesical chemotherapy and stratified as having IR disease according to the 2021 model were included. Main endpoint was RFS and PFS rates of the entire group, and of TaHG patients compared to other patients’ subgroups. Secondary endpoint was to evaluate the impact of maintenance chemotherapy on RFS and of PFS and to assess the best candidate for maintenance. KM curves were built to evaluate the risk of disease recurrence and progression and multivariable regression analyses to evaluate the impact of maintenance on RFS and PFS. The forest plot method was used to evaluate the subgroup of patients who benefit more from maintenance treatment. Results: Overall, 610 patients were included. Of these, 228 (38%) and 382 (63%) were primary and recurrent NMIBC, respectively. TaHG, TaLG and T1LG were found in 113 (19%), 440 (72%) and 57 (9%) of patients. RFS rates varied from 83% at 1 yr and 50% at 5 yrs. PFS rates varied from 99% at 1 yr and 93% at 5 yrs. Oncological outcomes of TaHG patients did not differ from those of TaLG or T1LG disease. On multivariable analyses maintenance was associated with improved RFS (HR 0.57, p<0.001) but not with PFS (HR 0.83, p=0.7). Maintenance was particularly effective in preventing recurrence among TaHG patients. Conclusions: We externally validated the homogeneity of IR disease spectrum regarding oncological outcomes, and we confirmed that selected TaHG patients harbor the same oncological outcomes of other IR subgroups. In IR disease, adjuvant chemotherapy with maintenance should be indicated to lower the risk of disease recurrence, especially in patients with TaHG tumors. SOURCE OF Funding: None.
