Macroscopic, but not microscopic, perivesical fat invasion at radical cystectomy is an adverse predictor of recurrence and survival

OBJECTIVE To examine whether the presence of microscopic (pT3a) or macroscopic (pT3b) disease worsens the prognosis relative to pT2 disease at radical cystectomy, as the prognostic significance of pT3a vs pT3b perivesical fat invasion (pT3) is controversial. PATIENTS AND METHODS In all, 242 patients with pT3 disease (pT3a in 88, pT3b in 121) had radical cystectomy and bilateral pelvic lymphadenectomy for transitional cell carcinoma of the urinary bladder; they were compared with 172 who had organ-confined muscle-invasive disease (pT2). For the analyses we used univariable and multivariable Cox regression models of recurrence and cancer-specific survival, adjusted for age, tumour grade, lymphovascular invasion and the presence of lymph node metastases. RESULTS In multivariable analyses, microscopic perivesical fat extension (pT3a) was not associated with higher recurrence (P=0.3) or the mortality rate (P=0.06) vs pT2 disease. Conversely, the presence of deep perivesical fat extension (pT3b) was associated with 1.8 times the rate of recurrence (P=0.002) and with twice the rate of death (P=0.001) vs pT2 disease. CONCLUSION These findings imply that a detailed assessment of the cystectomy specimen for the presence of microscopic perivesical fat invasion might not be necessary, as the presence of pT3a disease has no strong effect on recurrence or mortality. Moreover, patients with pT3a disease might not require more aggressive therapy than their counterparts with pT2 disease. However, further validation of our data is required.