Prognostic value of histopathological tumour growth patterns at the invasion front of T1G3 urothelial carcinoma of the bladder.

OBJECTIVE: The course of non-muscle-invasive urothelial carcinoma of the bladder (BC) staged T1G3 is hardly predictable and treatment is subject of intensive debate. In muscle-invasive BC, the infiltrative growth pattern at the tumour invasion front was able to predict patients' survival, in contrast to the nodular and trabecular growth pattern. The aim of this study was to evaluate this aspect in a series of primary T1G3 BC.
MATERIAL AND METHODS: The clinical and histopathological characteristics of patients with initial T1G3 BC treated between 1990 and 2007 at a single institute were retrospectively analysed. After independent blinded reassessment by two uropathologists, 205 patients were included in the study. The mean follow-up period was 6.7 years (range 0.4-13.2 years). All patients underwent transurethral resection of the bladder and opted for either initial cystectomy (19%) or repeat resection followed by adjuvant Bacillus Calmette-Guérin (BCG) instillation therapy (81%). In total, 34% of patients were cystectomized.
RESULTS: The most common invasion subtype was nodular (43.9%), followed by infiltrative (42.0%) and trabecular (14.1%) growth patterns. Progression and recurrence-free survival did not differ. However, cancer-specific survival rate was statistically significantly worse in infiltrative (59.3%) than in nodular (91.1%) and trabecular (86.2%) subtypes. These results were detected in the patient subgroups with initial radical cystectomy (p<0.01) and a primary bladder-sparing approach (p=0.02). In multivariate analysis of cancer-specific survival, carcinoma in situ and growth pattern showed statistical significance.
CONCLUSIONS: Tumour invasion pattern may be a strong predictor of cancer-specific survival and should be considered in counselling patients in selecting appropriate therapy for T1G3 BC.