Nodal and systemic recurrence following observation of a positive sentinel lymph node in melanoma

Background Two RCTs found no survival benefit for completion lymphadenectomy after positive sentinel lymph node biopsy compared with observation with ultrasound in patients with melanoma. Recurrence patterns and regional control are not well described for patients undergoing observation alone. Methods All patients with a positive sentinel node biopsy who did not have immediate completion lymphadenectomy were identified from a single-institution database (1995-2018). First recurrences were classified as node only, local and in-transit (LCIT) only, LCIT and nodal, or systemic. Regional control and factors associated with recurrence survival were analysed. Results Median follow-up was 33 months. Of 370 patients, 158 (42 center dot 7 per cent) had a recurrence. The sites of first recurrence were node only (13 center dot 2 per cent), LCIT only (11 center dot 9 per cent), LCIT and nodal (3 center dot 5 per cent), and systemic (13 center dot 8 per cent). The 3-year postrecurrence melanoma-specific survival rate was 73 (95 per cent c.i. 54 to 86) per cent for patients with node-only first recurrence, and 51 (31 to 68) per cent for those with initial systemic recurrence. In multivariable analysis, ulceration in the primary lesion (hazard ratio (HR) 2 center dot 53, 95 per cent c.i. 1 center dot 27 to 5 center dot 04), disease-free interval 12 months or less (HR 2 center dot 38, 1 center dot 28 to 4 center dot 35), and systemic (HR 2 center dot 57, 1 center dot 16 to 5 center dot 65) or LCIT and nodal (HR 2 center dot 94, 1 center dot 11 to 7 center dot 79) first recurrence were associated significantly with decreased postrecurrence survival. Maintenance of regional control required therapeutic lymphadenectomy in 13 center dot 0 per cent of patients during follow-up. Conclusion Observation after a positive sentinel lymph node biopsy is associated with good regional control, permits assessment of the time to and pattern of recurrence, and spares lymphadenectomy-related morbidity in patients with melanoma.