Presentation Authors: Koichiro Ogihara*, Eiji Kikuchi, Keisuke Shigeta, Masayuki Hagiwara, Ryuichi Mizuno, Mototsugu Oya, Tokyo, Japan
Introduction: In patients with Ta-3N0M0 upper tract urothelial carcinoma (UTUC) with a longer survival rate as compared to those with T4 and/or N+M0 UTUC, there is an ongoing debate with respect to the key risk factors which influence intravesical recurrence (IVR) after radical nephroureterectomy (RNU). Since conditional survival (CS) analysis provides better estimates of survival time at each follow-up time, we aimed to assess the changes in conditional IVR free rates after RNU and how the impact of well-known risk factors evolves over time, especially in Ta-3N0M0 UTUC patients.
Methods: We identified 682 patients with Ta-3N0M0 UTUC who underwent open or laparoscopic RNU from 1980 to 2015 at our 7 institutions. The CS was estimated using the multiplicative law of probability, illustrating IVR free survival with multiple Kaplan-Meier methods. The changing impact of parameters on IVR over time was assessed by multivariate Cox regression analysis.
Results: Median age was 71 years and median follow-up period was 48.4 months. Intravesical recurrence after RNU was detected in 295 patients (43.3%). Five-year IVR free survival (IVRFS) rates after surgery were 44.2% at baseline, but when we assessed the conditional IVRFS probability of surviving a certain number of years after RNU, the 5-year conditional IVRFS rate increased from 44.2% to 59.3%, 71.5%, 77.0% and 94.0% based on 1-, 2-, 3-, and 4-year survivorships (Figure left). Multivariate analysis revealed that pT2 or lower stage, previous history of a bladder tumor, and laparoscopic RNU were independent risk factors for developing IVR at baseline. We found that the effects of well-known predictive factors lost their statistical significance with time. However, the impact of laparoscopic RNU sustained their statistical power over time. We further demonstrated 5-year conditional probability of IVRFS as a function of prediction time. The probability of an additional 5-year IVR free survivorship (5|s) with open RNU gradually increases after surgery over time (47.9% at s=0 (baseline) to 95.9% at s=5), whereas laparoscopic RNU showed significantly lower IVRFS (32.5% at s=0 (baseline) to 85.7% at s=5) (Figure right).
Conclusions: CS analysis revealed that the probability of IVRFS increased with time in UTUC patients after RNU. Patients who undergo laparoscopic RNU with T2 or less pathological stage may be recommended for longer follow up to detect subsequent IVR.