Introduction: The optimal time interval between diagnostic excision of a primary cutaneous melanoma and sentinel node (SN) biopsy is unknown. The current study sought to determine whether this interval influenced the SN-positivity rate, recurrence or survival.
Methods: Data collected from 2004 to 2014 for a Dutch population-based cohort of patients with melanoma who underwent SN biopsy (SNB) within 100 days of initial diagnosis (n = 7660) and for a similarly specified cohort from a large Australian melanoma treatment centre (n = 3478) were analysed. Time to SNB was analysed continuously (in weeks) and categorically (per month). The effects of SNB timing on SN-positivity were assessed using multivariable logistic regression, and its effects on recurrence-free survival (RFS) and overall survival (OS) were assessed using Cox proportional hazard regression analyses. Advanced modelling using a multivariable Cox model with penalised splines for modelling the continuous effects of time to SNB on RFS and OS was also performed.
Results: In neither the Dutch nor the Australian cohort was there a significant association between time to SNB and SN-positivity in either cohort, nor was there an impact of time to SNB on RFS or OS in either cohort. The spline-based HR curves for RFS and OS confirmed these findings.
Conclusions: The time interval between diagnostic excision of a primary melanoma and SNB did not influence the SN-positivity rate or survival outcomes. This provides reassurance that neither early nor delayed definitive wide excision and SNB will adversely affect prognosis.
Keywords: Excision; Melanoma; Sentinel node; Survival; Time.
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