Sentinel lymph node biopsy in Japan.

Area of Science:

• Oncology
• Surgical Pathology
• Dermatology

Background:

• Intraoperative lymphatic mapping and selected lymphadenectomy (SLNB) are validated melanoma staging procedures in Japan, mirroring Western practices.
• Approximately 90% of Japanese university and cancer hospitals routinely perform SLNB, with about half of all melanoma patients undergoing the procedure.

Purpose of the Study:

• To discuss data from Japanese patients regarding the current status of SLNB for melanoma staging.
• To present the metastasis rates in sentinel lymph nodes (SLNs) based on tumor stage and primary tumor characteristics.

Main Methods:

• SLNB performed using variations of the Morton and Cochran standard procedure.
• Commonly used tracers include Tc(99m)-tin colloid or Tc(99m)-phytate for scintigraphy and patent blue violet or indigo carmine as blue dye.
• Indocyanine green is used in some institutions for fluorescent visualization under infrared cameras; detection rates exceed 95% with combined methods.

Main Results:

• Melanoma metastasis rates in SLNs varied significantly by pathological tumor stage (pTis: 0%, pT1: 10.7%, pT2: 21.0%, pT3: 34.0%, pT4: 62.4%).
• A significant correlation was observed between SLN metastasis rates and the presence of ulceration in the primary tumor.

Conclusions:

• SLNB is a widely adopted and effective method for melanoma staging in Japan.
• Tumor stage and ulceration are critical factors influencing metastasis risk in Japanese melanoma patients undergoing SLNB.