How much time is enough? Sentinel lymph node mapping time depends on the radiotracer agent

Area of Science:

• Nuclear medicine
• Oncology
• Surgical pathology

Background:

• Technetium-99m tilmanocept (TcTM) replaced technetium-99m sulfur colloid (TcSC) as the standard lymphoscintigraphy (LS) agent for melanoma patients in 2014.
• Sentinel lymph node biopsy (SLNB) is crucial for melanoma staging.
• Understanding the comparative performance of LS agents is vital for optimizing surgical procedures and patient outcomes.

Purpose of the Study:

• To compare TcTM and TcSC in melanoma patients undergoing SLNB.
• To evaluate differences in lymphoscintigraphy mapping time.
• To assess intra-operative sentinel lymph node (SLN) identification and false negative rates (FNR).

Main Methods:

• Retrospective analysis of SLNB procedures between 2010 and 2018.
• Stratification of patient data based on TcSC (n=258) or TcTM (n=133) usage.
• Statistical comparison using Student's t test and chi-squared test.

Main Results:

• Demographics, primary tumor characteristics, and total SLN identified were similar between TcTM and TcSC groups.
• TcTM demonstrated significantly shorter LS mapping times (51.8 min) compared to TcSC (195.1 min) (p < 0.01).
• No significant differences were observed in the proportion of positive SLN or FNR between the TcTM (25%) and TcSC (22%) groups.

Conclusions:

• TcTM offers a significant advantage by reducing LS mapping time while achieving comparable SLN identification rates to TcSC.
• The similar FNR suggests comparable diagnostic accuracy between the two agents.
• Further research is warranted to confirm equivalent oncologic outcomes and long-term efficacy.