Prognostic impact of percentage of squamous differentiation in patients with nonbilharzial squamous cell carcinoma and transitional cell carcinoma treated with radical cystectomy.

Abstract

498 Background: Squamous differentiation has been reported to occur in 10-22 % of transitional cell carcinoma. The prognostic impact of squamous differentiation is controversial. In addition, it remains unclear whether the percentage of squamous differentiation impact outcome of patients with nonbilharzial squamous cell carcinoma and transitional cell carcinoma treated with radical cystectomy Methods: We performed a retrospective study of patients with non-bilharzial squamous variants or squamous bladder carcinoma treated in two French institutions. The percentage of squamous differentiation was determined by an expert GU pathologist on radical cystectomy specimens. Progression-free survival (PFS) and cancer-specific survival (CSS) were analyzed according to the percent of squamous differentiation. Survivals were estimated using the Kaplan-Meier method and compared using multivariate Cox proportional hazard regression analysis. Results: Forty patients were identified including 28 and 12 patients which tumors were classified as transitional cell carcinomas cases with squamous cell differentiation and pure non-bilharzial squamous bladder carcinoma, respectively. Patients with tumors harboring more than 50% of squamous differentiation had a PFS of 6.3 months as compared to 60.2 months for those with squamous differentiation present in less than 50% (p = 0.014). In multivariate analysis, the percentage of squamous differentiation was the only independent prognostic factor for PFS (HR = 2.63 (IC 95%: 1.22-5.67). First site of recurrence of patients with squamous differentiation ≥50% were more frequently the pelvis (72% versus 17 %; p = 0.049). No difference in CSS were observed between patients with tumors < 50% or ≥50% squamous differentiation (16.3 months versus 62 months) (p = 0.2). Conclusions: Extensive squamous differentiation in bladder cancer is associated with poor PFS and pelvic progression, suggesting that those patients might benefit from adjuvant pelvic radiotherapy. Larger studies are needed to validate these findings.