E316: The young nodal basin: Update on regional metastasis and clinical outcomes in young cutaneous melanoma patients

The Multicenter Selective Lymphadenectomy Trials (MSLT) I and II evaluated the role of SLNB and completion nodal dissection (CLND), respectively, in the management of cutaneous melanoma patients. In prior studies, younger melanoma patients demonstrate higher rates of positive (+) sentinel lymph node biopsy (SLNB) and longer survival, the reasons for which are ill-defined.

Methods: We performed a follow up investigation of young melanoma patients utilizing the randomized, multinational MSLT I and II databases. Melanoma-specific survival (MSS) and recurrence rates were assessed for young adults (YA) (18-39 years old), adults (40-59) and older adults (60+) within each nodal management group.

Results:

YA patients had longer MSS than patients over 40 years (p=0.06 MSLT I, p< 0.01 MSLT II). In MSLT I, YA (n=366) were more likely to be female, smoke, and have thinner tumors than older patients. YA had a 24% +SLNB rate, significantly higher than that of older patients (p< 0.05). Among YA, patients undergoing SLNB (n=225) were more likely to have extremity melanoma than YA undergoing observation (OBS) (n=141) (p< 0.05). YA who underwent OBS had a lower rate of nodal metastasis at 7 years (15% OBS vs. 30% SLNB, p< 0.001). YA who underwent SLNB had shorter MSS than those who underwent nodal OBS (p< 0.05). There was no difference in MSS between OBS and negative SLNB cohorts [Figure]. On multivariable analysis, SLNB in YA was associated with worse MSS.

In MSLT II, YA patients were more likely to be female, smoke, and have thinner tumors and lower ulceration rates than older cohorts. Of patients who underwent no-CLND, YA had lower rates of nodal recurrence than patients over 40 (p=0.06). No clinicopathologic differences between CLND (n=159) and no-CLND (n=181) groups in YA were noted. YA who underwent CLND had a shorter MSS than the no-CLND group, although this did not reach statistical significance on univariate (p=0.14) or multivariate (p=0.11) analyses.

Conclusions: YA who underwent SLNB had shorter MSS than those who did not undergo SLNB, and CLND was not associated with improved MSS in YA patients. YA who underwent OBS had similar MSS to SLNB negative patients despite an estimated nodal metastasis rate of 15%. The lower rate of estimated lymph node metastasis in the OBS cohort suggests other physiologic mechanisms may be responsible for the improved survival seen in those who did not undergo SLNB. In the era of modern systemic therapies, further studies evaluating immunologic factors in young melanoma patients are warranted.