Occult lymph node metastases in patients with carcinoma invading bladder muscle: incidence after neoadjuvant chemotherapy and cystectomy vs after cystectomy alone

Objective: To investigate the effect of neoadjuvant chemotherapy (NAC) on the incidence of lymph node (LN) metastases in clinically node-negative (cN0) patients with carcinoma invading the bladder muscle (MIBC).

Patients and methods: Between 1990 and 2012, 828 consecutive patients underwent radical cystectomy (RC) with extended pelvic LN dissection (ePLND), of whom 441 had cT2-4N0M0 stage disease. A total of 83 patients received NAC then underwent RC and 358 patients underwent RC only. The ePLND template and the indication for NAC remained the same during the study period. The incidence of occult LN metastases was compared between the groups. Unadjusted and adjusted odds ratios (ORs) were calculated to investigate the influence of NAC, cT stage, gender and the preoperative staging technique used (computed tomography [CT] or positron emission tomography/CT) on the occurrence of LN metastases. Overall survival (OS) and disease-specific survival were analysed using the Kaplan-Meier method.

Results: Patients in the NAC group more often had locally advanced MIBC than patients in the non-NAC group (cT3-4: 88.0 vs 30.2%). In the NAC group, 19.3% of patients had LN metastases vs 28.5% of the patients in the non-NAC group (P = 0.099). In the patients with cT3-4 disease, the occurrence of LN metastases was significantly lower in the NAC group than in the non-NAC group (21.9 vs 40.7%, respectively, P = 0.002). In multivariable analysis, adjusting for cT stage, gender and staging method, NAC was independently associated with a lower likelihood of LN metastases (OR: 0.41, 95% CI 0.21-0.79; P = 0.008). Among the patients with cT3-4 disease, the median OS was significantly longer in the NAC group than in the non-NAC group (68.0 vs 23.0 months, P = 0.047) CONCLUSION: These data suggest that, along with a downstaging effect on the primary bladder tumour, NAC is associated with a lower incidence of occult LN metastases at the time of RC.