E329: Long term outcomes and pattern of recurrence in patients with thin melanoma and a negative sentinel lymph node biopsy- a single center experience

Objective: The majority of patients diagnosed with melanoma have thin melanomas (TM) (≤1 mm). Data on the rate and pattern of recurrence after a negative sentinel lymph node biopsy (SLNB) are sparse.

Methods: We retrospectively searched our institutional database and retrieved the records of patients with TM who underwent a SLNB with negative results. We analyzed patterns of recurrence, time to recurrence and mode of diagnosis. 

Results:

Thirteen of the 198 patients with TM and negative SLNB results had tumor recurrence (6.5%): 2 local in-transit (15.4%), 3 regional (21.3%) and 8 distant (61.5%). Distant recurrences tended to occur later than local or regional ones (median disease-free survival = 50 months (95% confidence interval [CI]: [36.1-63.9]) vs. 34 and 15 months [95% CI: 5.4-24.6], p=0.005, respectively). The percentage of patients with tumor thickness ≥0.8 mm was higher among those who sustained recurrence (84.6% vs. 64.9% for no recurrence, p=0.04). The majority of patients with recurrence were not being followed-up when diagnosed (69%), and they presented due to clinical symptoms. Patients with recurrence had lower survival compared to those without recurrence (median: 118 months vs. ongoing survival, p< 0.001, respectively).

 

Conclusions:

Melanoma recurrence in patients with TM and negative SLNBs is rare, tends to be distant and negatively affect prognosis. Recurrence tends to occur in patients with melanoma thickness ≥0.8 mm.  Further studies are needed to identify patients with high recurrence risk and determine optimal follow-up protocols.