Incidence and effect of variant histology on oncological outcomes in patients with bladder cancer treated with radical cystectomy

Introduction We sought to describe incidence of histological variants after radical cystectomy (RC) due to bladder cancer (BCa). Moreover, we investigated survival outcomes accounting for this parameter. Methods We retrospectively evaluated data from 1,067 patients with BCa treated with RC between 1990 and 2013 at a single tertiary care referral center. All specimen were evaluated by dedicated uropathologists. Univariable and multivariable Cox regression analyses tested the effect of different histopathological variant on recurrence, cancer-specific mortality (CSM), and overall mortality (OM) after accounting for all available confounders. Results Of 1,067 patients, 729 (68.3%) harbored pure urothelial BCa while 338 (31.7%) were found to have a variant. Considering uncommon variants, 21 (2.0%) were sarcomatoid, 10 (0.9%) lymphoepitelial, 19 (1.8%) small cell, 109 (10.2%) squamous, 89 (8.3%) micropapillary, 23 (2.2%) glandular, 34 (3.2%) mixed variants, and 33 (3.1%) were found with other types of variants. With a median follow-up of 6.2 years, 343 recurrence, 365 CSM, and 451 OM were recorded, respectively. At multivariable Cox regression analyses, the presence of small cell variant was associated with higher recurrence (hazard ratio [HR] = 3.47, P<0.001), CSM (HR = 3.30, P<0.04), and OM (HR = 2.97, P<0.003) as compared with pure urothelial cancer. Conversely, no survival differences were recorded considering other histological variants (all P> 0.1). Conclusion Our study confirms that histological variant is not an infrequent event at RC specimen. However, in our single-center series, only patients found with small cell variant were associated with a negative effect on survival after RC.