Objective To determine whether growth rate (GR) of cutaneous melanoma predicts the histological sentinel lymph node (SLN) positivity.
Design Retrospective cohort study.
Setting Two tertiary melanoma referral centers.
Patients A total of 698 patients with invasive primary cutaneous melanoma in whom the SLN was identified between January 1, 2000, and June 30, 2010.
Main Outcome Measure Based on previous studies, a surrogate measure for GR in primary invasive melanoma was calculated as the ratio of Breslow thickness to time to melanoma development.
Results The SLN was positive in 20.2% of patients. Multivariate logistic regression analysis revealed that GR, Breslow thickness, and the presence of microscopic satellitosis were independently associated with SLN positivity. The probability of SLN positivity was 8.2% for slow-growth melanomas (<0.10 mm/mo) compared with 19.8% for intermediate-growth melanomas (0.10-0.50 mm/mo) and 37.7% for fast-growth melanomas (>0.50 mm/mo). Growth rate was not an independent predictive factor for survival.
Conclusion Growth rate of primary cutaneous melanoma, together with Breslow thickness and the presence of microscopic satellitosis, predicts the histological SLN positivity.