The clinical value of nanocarbon suspension and methylene blue in sentinel lymphatic tracing and pathologic fine sorting of penile cancer: a multicentre prospective study.

OBJECTIVE

To compare nanocarbon suspension and methylene blue as lymphatic tracers in inguinal lymph node mapping and sorting during surgery for penile cancer.

METHODS

This multicentre study included 62 patients (2020-2024); 33 underwent sentinel lymph node biopsy (SLNB) and 29 underwent inguinal lymph node dissection (ILND). SLNB patients were divided into control (no tracer), nanocarbon, or methylene blue groups (ChiCTR2200063416). Outcomes included lymph node detection rate (LNDR), number of lymph nodes per side (NOLNPIS), metastasis positive rate (PROLM), and operation time (OT). ILND patients were grouped into nanocarbon-assisted sorting (NLFLNSG) or traditional sorting (TLNSG), with comparisons of NOLNPIS, PROLM, OT, and lymphatic leakage rate (PLLR).

RESULTS

Both tracers effectively stained lymph nodes without adverse effects. During SLNB, methylene blue significantly improved LNDR (p = 0.013), NOLNPIS (p = 0.015), and reduced OT (p < 0.0001) compared to control, but PROLM showed no difference. In ILND, NLFLNSG yielded more lymph nodes than TLNSG (p = 0.043), with no significant differences in PROLM, OT, or PLLR.

CONCLUSION

Nanocarbon and methylene blue are safe and effective for lymphatic tracing in penile cancer SLNB, improving node identification and surgical efficiency. Nanocarbon-assisted sorting in ILND increases lymph node retrieval, aiding pathological staging and treatment guidance.