Risk of Recurrence with Desmoplastic Melanoma and Desmoplastic Neurotropic Melanoma (DNM)

Historically, local recurrence with desmoplastic neurotropic melanoma (DNM):
- Has been high
In a retrospective analysis of 280 patients with DNM and desmoplastic melanoma:
- Quinn et al found:
  - A significantly greater local recurrence rate:
    - Associated with margins of less than 1 cm compared with margins greater than 2 cm (P=0.001):
      - No significant benefit was found when excision margins of 1 to 2 cm and greater than 2 cm were compared:
        
        Although the odds ratio for recurrence was 2:1 for the group with 1- to 2-cm margins compared with the group with greater than 2-cm margins
- Chen et al:
  - Noted a 6% crude local recurrence rate in their surgery-alone group:
    - This excellent local control rate was achieved despite 27.7% of the tumors having a mitotic rate of 5 or more, 14.9% of tumors being ulcerated, and 40.5% of tumors having a Breslow depth greater than 4 mm
In the series reported by Chen et al:
- Four patients had DNM involving named nerves
- All patients received adjuvant RT:
  - Covering the primary excision site and the involved nerve and its route to the base of the skull
- Local control was achieved in these patients, although one patient died of metastatic disease
- RT is important for these patients:
  - As recurrence extending beyond the base of the skull may not be surgically salvageable
Strom et al:
- Analyzed 277 patients with desmoplastic melanoma:
  - Of whom 113 (40.8%) received RT
- They found two subsets of patients who seemed to gain no benefit from RT:
  - These groups were those with:
    - Negative resection margins
    - A non-head and neck tumor location
    - A Breslow thickness of ≤ 4 mm
    - No perineural invasion
  - A patient with a head and neck tumor location with perineural invasion (PNI):
    - RT would be indicated based on these data
Guadagnolo et al:
- Analyzed 130 patients with desmoplastic melanoma:
  - Of whom 55% received adjuvant RT
- Although local control was not found to be significantly different among those with PNI versus those without:
  - 81% vs 88%, respectively; P=.52:
    - When local control outcomes were stratified by receipt of postoperative RT:
      - Patients with PNI who received RT had significantly better local control than those who did not:
        
        91% vs 63% at 10 years, respectively; P=.02
      - For those patients who clearly did not have PNI:
        
        RT did not significantly improve local control:
        
        90% with RT vs 85% without RT at 10 years; P=.82
References:
- Chen JY, Hruby G, Scolyer RA, et al. Desmoplastic neurotropic melanoma: a clinicopathologic analysis of 128 cases. Cancer. 2008;113:2770-2778.
- Guadagnolo BA, Prieto V, Weber R, et al. The role of adjuvant radiotherapy in the local management of desmoplastic melanoma. Cancer.2014;120:1361-1368
- Quinn MJ, Crotty KA, Thompson JF, Coates AS, O’Brien CJ, McCarthy WH. Desmoplastic and desmoplastic neurotropic melanoma: experience with 280 patients. Cancer. 1998;83:1128-1135.
- Strom T, Caudell JJ, Han D, et al. Radiotherapy influences local control in patients with desmoplastic melanoma. Cancer. 2014;120:1369-1378.