Primary Cutaneous Melanoma with Regression Does not Require a Lower Threshold for Sentinel Lymph Node Biopsy

Abstract

Introduction

Histological evidence of primary tumor regression (RG) is observed in 35% or fewer patients with cutaneous melanoma. Some advocate a lower threshold for sentinel lymph node (SLN) biopsy when RG is present.

Methods

We identified 1,349 patients presenting to our center with clinically localized cutaneous melanoma between 1995 and 2004. Of these, 344 demonstrated histological RG in their primary melanoma. A retrospective analysis of their medical records was performed to obtain clinical and pathological information.

Results

The median Breslow depth for the 344 patients with RG was 1.1 mm versus 1.5 mm for 1,005 patients with no regression (NRG) (P < 0.005). SLN biopsy was performed in 64% of patients with RG and 72% without. Positive SLN was more common in those with NRG than in those with RG (18% vs 10%, P = 0.005). Only one RG patient with thin melanoma (≤1 mm, Clark IV) had a positive SLN. When stratified by Breslow depth, patients with RG had lower rates of SLN positivity in all groups (≤1.0mm, >1.0 and ≤2.0mm, >2 and ≤4 mm, and >4.0 mm). Recurrence was more common in patients with NRG (21% vs 12%; P < 0.005). Both local and systemic recurrence occurred more commonly in patients with NRG (4% vs 1%, P = 0.002 and 8% vs 3%, P < 0.005, respectively)

Conclusions

The presence of histological RG in a primary melanoma predicts neither SLN positivity when stratified by Breslow depth nor increased risk of recurrence when compared with melanomas with NRG.