Lymphatic mapping and sentinel lymph node biopsy in urinary bladder cancer: A SPECT/CT-based experience

Area of Science:

• Uro-oncology
• Nuclear medicine imaging
• Surgical oncology

Background:

• Sentinel lymph node (SLN) mapping offers potential for improved nodal staging in bladder cancer.
• Minimizing morbidity associated with pelvic lymph node dissection (PLND) is a key objective.
• Feasibility, accuracy, and influencing factors of SLN mapping require further investigation.

Purpose of the Study:

• To assess the feasibility and diagnostic accuracy of SLN mapping in bladder cancer patients.
• To evaluate the impact of tumor stage, neoadjuvant chemotherapy (NAC), and imaging modality on SLN detection.
• To compare SLN identification with standard PLND findings.

Main Methods:

• Prospective study of 35 patients with urothelial carcinoma undergoing radical cystectomy.
• Preoperative peritumoral injection of ^99mTc-phytate followed by lymphoscintigraphy and SPECT/CT.
• Intraoperative SLN detection using a handheld gamma probe, compared with PLND.

Main Results:

• SLN mapping achieved patient-based detection rates of up to 68.6% with a gamma probe.
• Detection rates were highest in early-stage (T1-T2) and NAC-positive patients (100% intraoperative localization).
• A patient-based false-negative rate of 25% was observed; hemipelvis-based analysis showed no false negatives. Atypical lymphatic drainage was noted in 6% of patients.

Conclusions:

• SLN mapping is technically feasible in bladder cancer, revealing variable lymphatic drainage.
• Performance is influenced by tumor stage, NAC, and imaging modality.
• SLN mapping may complement PLND for enhanced staging and potentially enable tailored lymphadenectomy.