What is the role of radiation therapy (RT) in the treatment of lentigo maligna melanoma?

Updated: Dec 19, 2019
  • Author: Winston W Tan, MD, FACP; Chief Editor: William D James, MD  more...
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Answer

Radiation therapy (RT) may be an option for patients who are not surgical candidates (eg, due to comorbidities, impact on function, or cosmesis); in patients who refuse surgery; or in whom surgery has failed, with a positive margin. For lentigo maligna treated with definitive primary RT, a literature review by Fogarty et al reported a recurrence rate of 5% after a median of reported follow-up of 3 years. [29]

These authors describe their experience with definitive RT for lentigo maligna at their center, including decisions that need to be made in RT planning and treatment, and management of adverse effects. They note that effective treatment requires accurate mapping of the tumor volume, which in lentigo maligna extends to the bottom of the appendageal structures in the dermis and includes hair follicles and sweat glands. Underestimation of this area, which is usually larger than than the pigmented lesion visible to the naked eye, has led to field-edge recurrences. [29]

The Radiotherapy or Imiquimod in Complex Lentigo Maligna (RADICAL) trial, currently in progress, is investigating the effectiveness of using either RT or imiquimod to treat lentigo maligna when surgery is not possible, is refused, or fails.


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