Does “low risk” muscle invasive bladder cancer actually exist?

Abstract

308 Background: Despite level one evidence demonstrating improved survival with neoadjuvant chemotherapy (NAC), studies suggest that many eligible patients with muscle invasive bladder cancer (MIBC) never receive it prior to radical cystectomy (RC). Our objective was to determine if the absence of known pre-operative risk factors can indeed stratify for low risk of extravesical disease with RC alone. Methods: We identified consecutive NAC-naive patients with clinical stage cT2N0M0 urothelial type bladder cancer treated with RC at our center. cT2 patients with either hydronephrosis, transurethral resection (TUR) specimens containing lymphovascular invasion (LVI), or mixed variant histology were grouped as high risk. Clinicopathologic and survival outcomes were compared to cT2 patients without these adverse features, who were grouped as low risk. Results: Of 251 cT2 patients, 119 (47.4%) were high risk [LVI=31, hydronephrosis=69, mixed histology=54; ≥2 risk factors=70]. High and low risk cohorts did not differ in age, gender, race, BMI, smoking, co-morbidities, prior intravescial therapy, or treatment delay. At time of RC, high risk patients more often had lymph node metastasis (38.6% v. 26.7% p=0.04) & tumor upstaging to pT3/4 (53.7% v. 40.2 p<0.001), with significantly less achieving pT0 (2.5% v. 12.1% p=0.004). There was no difference in adjuvant chemotherapy rates (26.4% v. 25% p=0.8). Two and five year cancer-specific survival (CSS) was 84.8% and 62.3% for low risk patients, but only 59.5% and 42% for high risk patients (p=0.008), with competing risk analysis revealing worse bladder cancer specific mortality (BCSM) (sub HR=2.08 [95%CI=1.36 – 3.2]). Odds Ratio for BCSM was 1.29 (95%CI=0.68-2.5) if one risk factor was present, & 3.2 (95%CI=1.7-5.8) if two risk factors. Only hydronephrosis (2.2 [95%CI=1.2-4.2]) and mixed histology (2.4 [95%CI=1.2-4.8]) were independently associated with worse BCSM on multi-variable analysis. Conclusions: Good cancer control is provided by RC alone to many patients with cT2 MIBC without adverse risk factors, particularly if hydronephrosis & mixed variant histology is absent. However, tumor upstaging and lymph node involvement is not trivial even in low risk patients, which must be included in informed decision making on NAC.