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.