Histologic variants associated with biological aggressiveness and poor prognosis in patients treated with radical cystectomy.

Background: The prognostic value of histologic variants (HV) after radical cystectomy (RC) remains controversial. We evaluated the clinicopathological features and prognosis in patients with pure urothelial carcinoma (UC) and HV following RC.

Methods: From 1990 to 2015, 286 patients with bladder cancer were treated with RC at six Kitasato University-affiliated hospitals. All patients were divided into two groups: pure UC and HV, which contained pure variants and mixed-type UC with variant pattern. A comparison of patient characteristics between the two groups was made to assess the clinicopathological features, and statistical analyses were performed to investigate prognosis in the two groups.

Results: Of the 286 patients, 226 (79%) had pure UC, while 60 (21%) had HV. Of all HV, pure variants accounted for 45% (n = 27). The prevalence of lymph node involvement, locally advanced stage (≥ pT3), positive soft tissue surgical margin and lymphovascular invasion were significantly higher in patients with HV than in those with pure UC. Patients with HV showed worse disease-free survival and cancer-specific survival than those with pure UC (P = 0.009 and 0.003, respectively). In multivariate analysis, HV and lymph node involvement were independent predictors of worse disease-free survival (P = 0.017 and 0.001, respectively). HV, locally advanced stage, lymph node involvement, and positive soft tissue surgical margin were also confirmed as independent predictors of worse cancer-specific survival (P = 0.011, 0.012, 0.003 and 0.010, respectively.).

Conclusions: HV was associated with greater biological aggressiveness and worse prognosis than pure UC.