Background: Hypothetically, delay between melanoma diagnosis and SLNB could affect outcomes, either adversely by allowing growth and dissemination of metastases, or beneficially by allowing development of an anti-melanoma immune response. Available data are conflicting about the effect of SLNB delay on patient survival. Our objective was to determine whether delay between initial diagnosis and SLNB affects outcomes in patients with cutaneous melanoma. Study Design: We performed query and analysis of a large prospectively maintained database of patients with primary cutaneous melanomas undergoing SLNB. An independent dataset from MSLT-1 (Multicenter Selective Lymphadenectomy Trial-1) was used for validation. Primary outcomes included disease-free survival and melanoma-specific survival. Results: Early and delayed SLNB were defined as less than 30 and 30 or more days from initial diagnosis, respectively. There were 2,483 patients that met inclusion criteria. Positive sentinel lymph nodes were identified in 17.4% (n = 432). Among all patients, 42% had SLNB 30 or more days after diagnosis and 37% of positive sentinel lymph nodes were at 30 or more days. No differences in sex, anatomic site, or histopathologic features were identified between the 2 groups. There was no difference in melanoma-specific survival or disease-free survival between those undergoing early or delayed SLNB. Examination of MSLT-1 trial data similarly demonstrated no difference in survival outcomes. Conclusions: This, the largest study on this subject to date, found no adverse impact on long-term clinical outcomes of patients due to delay of SLNB beyond 30 days. The MSLT-1 data confirm this result. Patients can be reassured that if the operation is performed 30 or more days after diagnosis, it will not cause harm.
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