Background
Retrospective analysis (MD Anderson Cancer Center) of desmoplastic melanoma (DM) — a rare neurotropic variant with high local recurrence rate after surgery alone. 130 patients with DM of the head/neck and other sites treated with surgery ± adjuvant RT. Assessed the impact of RT on local recurrence and survival. DM is characterized by fibromatous stroma, neurotropism, and high LR risk.
Interventions and follow up
Arm A: Surgery + adjuvant RT
Arm B: Surgery alone; retrospective compariso
Primary endpoint: Local recurrence rate
mFollow up: Not specified
Arm B: Surgery alone; retrospective compariso
Primary endpoint: Local recurrence rate
mFollow up: Not specified
Results
Local Recurrence (surgery alone): ~20–26%
Local Recurrence (surgery + RT): ~7–10%
Head/neck DM LR risk: Highest without RT; adjuvant RT significantly reduces LR
OS: No significant OS difference between treatment groups
Local Recurrence (surgery + RT): ~7–10%
Head/neck DM LR risk: Highest without RT; adjuvant RT significantly reduces LR
OS: No significant OS difference between treatment groups
Adverse events
Main adverse events: Adjuvant RT toxicity site-dependent (head/neck: mucositis, xerostomia, skin reaction). RT doses typically 60–66 Gy given neurotropic nature. Acceptable toxicity in this series.
Conclusions
Adjuvant RT significantly reduces local recurrence in desmoplastic melanoma compared to surgery alone (~7–10% vs ~20–26%). Given DM's neurotropic nature and high LR risk — particularly for head/neck sites — adjuvant RT should be strongly considered after surgical excision, especially when margins are close or positive.
Key Limitations
Key Limitations: Retrospective, single-institution; potential selection bias (higher-risk tumors may have received RT); limited OS benefit suggests systemic spread remains the major driver of mortality; no standardized pathologic criteria for "desmoplastic"; modern MRI-guided surgical planning may reduce margins needed.
Clinical Context
Desmoplastic melanoma is a distinct histologic subtype with neurotropism and high LR risk, particularly for H&N. Adjuvant RT is widely recommended for DM, especially with positive margins, deep invasion, or perineural invasion to named nerves. Unlike conventional melanoma, DM has a low rate of sentinel node positivity (~4%) and rare LN metastases. RT dose typically 60 Gy (vs 30/5 for nodal basins) given neurotropism requiring higher BED.
References