TUMOR BUDDING: PROGNOSTIC VALUE IN MUSCLE-INVASIVE BLADDER CANCER.

OBJETIVES: To assess if 'tumour budding' (TB) behaves as a poor prognostic factor in muscle-invasive bladder carcinoma (MIBC). TB is the presence of tumour cells isolated or in small groups of fewer than five cells located at the tumour invasion front.

MATERIAL AND METHODS: Retrospective study of 106 patients with MIBC who underwent radical cystectomy. A cytokeratin AE1/AE3 immunostaining was applied to identify and quantify TB by the 'hot-spot' method. The variables evaluated were: age, gender, TNM stage, associated CIS, differentiation degree, tumour size, tumour location, lymphatic, venous or perineural invasion, p53, Ki67, molecular subtype (basal/luminal) and chemotherapy. Main variables were overall and cancer-specific survival.

RESULTS: The mean follow-up time was 47 ± 46.45 months. The mean TB count was 32.3 ± 25.9 'buds'. The ROC curve established 14 'buds' as the cut-off point: the median survival rate for the 'low-grade TB' group (≤14 'buds') was 69.5 months, and for the 'high-grade TB' group (>14 'buds') was 18.5 months (p = 0.003). In the multivariate analysis, independent predictive variables regarding mortality were: age, TB and TNM stage. Patients with more than 14 'buds' had 2.27 times more risk of mortality, CI95% :1.19-4.34, p = 0.013. In addition, the risk of mortality rises progressively as the number of 'buds' increases, at a rate of 2% per 'bud'.

CONCLUSION: According to our results, TB becomes an independent predictor factor for cancer-specific mortality in MIBC, with a cut-off point of 14 'buds'.