A role for pelvic sentinel lymph nodes in lower extremity melanoma?

Consensus on management of pelvic sentinel lymph nodes (PSLNs) has not been reached and thus the extent of sentinel lymph node biopsy (SLNB) of the groin in melanoma patients varies among centers and surgeons. Lymphatic drainage to PSLNs is often identified in, but the diagnostic and clinical relevance of PSLNs has been debated. Our aim was to determine if the presence of PSLNs affected recurrence or survival rates in patients with melanoma in the lower extremities.

This retrospective study consisted of 702 patients with cutaneous melanoma operated between 2005 and 2018. Of these, 134 patients with melanoma in the lower extremities were included in the study. Images of lymphoscintigraphy and SPECT-CT studies were thoroughly observed together with surgery reports to define the status of SLNs.

Overall, 85 of 134 patients went through SLNB and 28 of them had PSLN identified. Two had their PSLN removed, which led 26 patients with PSLN to be compared to the 57 who did not have PSLN identified. We did not find statistically significant differences in overall recurrence (26.9% versus 28.0%, p = 1.00), regional nodal recurrence (11.5% versus 15.8%, p = 0.67), local or in-transit recurrence (19.2% versus 8.8%, p = 0.17), or distant recurrence rates (15.4% versus 19.3%, p = 0.66). Disease-free survival did not differ between the groups (median 23.0 (IQR 15.0-39.0) versus 19.0 (IQR 10.3-61.8) months, p = 0.82). Likewise, there was no statistically significant difference in melanoma-specific 5-year survival (78.6% versus 87.2%, p = 0.42).

We did not find more frequent recurrence, shorter disease-free survival, or poorer melanoma-specific survival in patients with drainage to PSLN. Our findings strengthen the evidence that PSLNs should not be routinely biopsied if they are not the first-tier nodes.