SAN DIEGO What is an adequate margin for surgical excision of melanoma?
Beyond a clear margin, "we really don't know," Dr. Duane C. Whitaker said at a melanoma update sponsored by the Scripps Clinic.
That's why there's a place for Mohs surgery in the treatment of melanoma.
"Mohs for melanoma has not caught on terribly widely, but on the other hand I don't believe it will ever disappear because there are times when you simply need Mohs surgery to be able to treat the primary melanoma in a reasonable way," said Dr. Whitaker, a dermatologist and Mohs surgeon who practices in Tucson, Ariz.
He described Mohs surgery as "the best method we have to establish tumor-free margins when we remove any type of visible tumor. Any time that we don't truly know what margin beyond clear should be achieved to help the patient, then probably there is some role for Mohs surgery."
The best studies to date have demonstrated that the cure rate with Mohs surgery in stage I and stage II melanomas is at least equivalent to local excision with a predetermined margin, he said.
Mohs surgery has several traditional advantages. It spares tissue in the ear, nose, and other critical anatomic sites; determines margins precisely; allows for immediate reconstruction; allows minimum wound and repair; and allows physicians to start additional and adjunctive therapies right away.
The technique is especially useful for neurotrophic and desmoplastic melanomas since "they're often deeper and wider than you would anticipate," he said.
A key factor when deciding whether to perform Mohs or not "is your comfort with following [the patients], talking about the issues involved, and being ready for that patient who may come back with a lump that you didn't expect," continued Dr. Whitaker, who is the current vice president of the American College of Mohs Surgery.
Beyond the realm of melanoma, Mohs surgery seems to have applications as the method to establish free margins of a primary tumor when evidence does not support a survival benefit achieved by more radical surgery. "If all melanomas occurred in the trunk or proximal extremities where we can do a wider local excision with 3-cm margins, they wouldn't be so difficult to treat," he said, "but when they occur on the digits, the nose, or the periocular areas," that adds complexity.
Mohs surgery seems to be the most reliable method to obtain local free margins at the time of surgery. "It is considered one component of treatment for those tumors which have substantial metastatic risk," Dr. Whitaker said. "Assessment of the host and tumor characteristics will help you determine the full therapeutic plan."
Mohs is 'the best method we have to establish tumor-free margins when we remove any type of visible tumor.' DR. WHITAKER
A melanoma lesion on a patient's nose is shown before Mohs surgery.
The same patient is shown after Mohs was performed to remove the lesion. Photos courtesy Dr. Duane C. Whitaker