Does the time interval between sentinel lymph node biopsy and completion lymph node dissection affect outcome in malignant melanoma? A retrospective cohort study.

Nodal clearance was recommended after positive sentinel lymph node biopsy (SLNB) despite further metastases to the regional lymph node basin being found in only 6-21% in the literature. This retrospective study was conducted to determine the role of the time interval between excision of primary melanoma and confirmed metastasis in the sentinel lymph node biopsy as well as the one between positive sentinel lymph node biopsy (SLNB-positive patients) and subsequent completion lymph node dissection (CLND) on the presence of metastases. The monocentric analysis included 121 patients with a history of completion lymph node dissection after positive SLNB from January 2005 to October 2013. Additional metastases in the regional lymph node basin (non-sentinels) were found in 14.05% (n = 17). Significant risk factors for the presence of metastases in CLND were the time between confirmed primary tumour to metastasis in sentinel lymph nodes (SLN) (p = 0.0034), N-category of TNM-classification (p = 0.0066) and independent of thickness of primary tumour (p = 0.11). If SLNB was performed up to forty-three days after confirmed primary melanoma, subsequent lymph node dissection was positive in less than 9.1%. When SLNB was performed with a delay of more than 80 days, all patients had metastases in the CLND specimens. Our data analysis suggests that delays in subsequent procedures of SLNB after diagnosis of primary melanoma may have a greater impact on positivity of non-sentinel lymph nodes than previously assumed. Our retrospective analysis may indicate the reconsideration of time schedule in the management of primary melanoma to potentially avoid local relapse in the draining lymph node region after positive SLNB.