Sentinel lymph node biopsy in thick malignant melanoma: a 10-year single unit experience

Between the years 2000-2010, 195 patients were diagnosed with ≥4 mm Breslow thickness malignant melanoma in our unit. Median follow-up was 36.8 months. 49% of patients were male and 51% were female. Median age was 74 years. The commonest melanoma type was nodular (55%). The commonest tumour location was on the extremity (45%). 64% of tumours were ulcerated. Median mitotic rate was 9. Median Breslow thickness was 7 mm 66 patients underwent sentinel lymph node biopsy. 44 (67%) patients had negative results and the remaining 22 (33%) patients were positive for metastatic melanoma. There was no statistically significant correlation between any of the patient or tumour variables (age, sex, melanoma type, melanoma site, Clark level, Breslow thickness, mitotic rate, ulceration) and sentinel lymph node status. Patients with Breslow thickness melanoma of <6 mm had a significantly better 5-year disease free and overall survival compared with those patients with >6 mm Breslow thickness melanoma (63.5% vs. 32.9%; P=0.004 and 73.9% vs. 54.7%; P=0.02 respectively). Recurrence rate was 50% in those with positive sentinel lymph node biopsy compared to 23% in those with negative results. Distant recurrence was the commonest in both groups. 5-year disease free survival was 64.1% in the SLNB -ve group and 35.4% in the SLNB +ve group (P=0.01). There was no significant difference in overall survival between the SLNB -ve and SLNB +ve groups (70.3% vs. 63.7% respectively; P=0.66). We conclude that sentinel lymph node biopsy in our unit has provided no survival benefit in those with thick melanoma over the past 10 years but is an important predictor of recurrence free survival. Breslow thickness remains an important predictor of disease free and overall survival in thick melanoma.