No statistically significant difference in overall survival (OS) with addition of adjuvant radiation therapy in patients with desmoplastic melanoma (p=0.1312), even when matched for propensity scoring (p=0.6267).
Clinical Pearls
No statistically significant difference in overall survival (OS) with addition of adjuvant radiation therapy in patients with desmoplastic melanoma (p = 0.1312), even when matched for propensity scoring (p =0.6267)
Factors that worsened overall survival include older age, T stage ≥2, N stage ≥1, and no receipt of immunotherapy
Demographic makeup of the study population of desmoplastic melanoma patients were primarily male, Caucasian, and between ages 50-74 years old
Discussion:
Desmoplastic melanoma is a rare & aggressive form of melanoma. Diagnosed at higher stages and having higher rates of local recurrence, desmoplastic melanoma confers greater levels of morbidity. Due to the elevated rates of recurrence, which are estimated to be as high as 60%, radiotherapy (RT) has been utilized for potential prevention of recurrence. However, no evidence-based guidelines exist on the utility of RT among patients with desmoplastic melanoma, and therefore this study sought to analyze available data through the National Cancer Database to assess overall survival amongst those receiving radiation therapy.
This was a retrospective cohort study with the inclusion criteria of patients age ≥18 years with non-metastatic desmoplastic melanoma confirmed by histological analysis. Of the 3,527 patients meeting inclusion criteria, 534 (15.1%) received adjuvant radiation therapy. Epidemiological makeup of those included in the study were primarily male, Caucasian, and between 50 to 74 years old. Of note, those who were receiving immunotherapy and therefore have worse baseline prognostic factors were more likely to have additionally been receiving radiation therapy, therefore potentially modifying the perceived effect of radiation therapy. To address this, the authors performed propensity score matching to compare overall survival outcomes, with the variables matched being T stage, N stage, and surgical margin status.
This study found no significant difference between overall survival rates among the two cohorts, with the overall survival prior to propensity matching being 133.9 months in the control group and 111.4 months in the cohort receiving radiation therapy (p = 0.1312). When matched for propensity scoring, no statistical difference was found, with the overall survival for the control cohort being 101.8 months and the intervention group being 111.4 months (p =0.6267). While this was the first study of this size to assess the survival benefit, or lack thereof, of radiation therapy in desmoplastic melanoma patients, it was limited by its retrospective design. Furthermore, due to data limitations from the database used, the rates of local recurrence were not analyzed. While this study may shed light on a rare disease with a poor prognosis, further prospective evaluation of radiation therapy is needed to inform clinical practice.
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