Conference Coverage

Merkel cell carcinoma management undergoes revolution


 

REPORTING FROM SDEF HAWAII DERMATOLOGY SEMINAR

– The treatment of Merkel cell carcinoma is rapidly becoming much less toxic and more effective – and dermatologists have a key role in making this happen, Paul Nghiem, MD, PhD, declared at the SDEF Hawaii Dermatology Seminar provided by Global Academy for Medical Education/Skin Disease Education Foundation.

Dr. Paul Nghiem, professor of medicine and head of dermatology at the University of Washington, Seattle Bruce Jancin/MDedge News

Dr. Paul Nghiem

That’s because dermatologists are typically the physicians who make the diagnosis of Merkel cell carcinoma (MCC), so they’re on the scene from the outset and well positioned to help direct early management of this particularly aggressive malignancy, explained Dr. Nghiem, professor and head of dermatology at the University of Washington, Seattle.

“The management of Merkel is pretty high stakes, and if you get it right at the beginning it makes a huge difference in the side effects, as well as the chances that the patient will have the disease under control,” said Dr. Nghiem, who is sometimes called “the Merkel man” because of his many pioneering contributions to the field.

Better early management

Getting early management right, he added, hinges upon ordering a baseline PET-CT scan to search for metastases before performing definitive surgical excision of the primary tumor.

“There are really important prognostic and therapeutic implications for a baseline scan in almost any patient with early Merkel – and that’s a very different situation than with melanoma,” the dermatologist said. “There’s at least a threefold higher likelihood that the cancer has spread asymptomatically at baseline with Merkel cell carcinoma than with melanoma.”

In a soon-to-be-published study by Dr. Nghiem and coworkers, baseline imaging resulted in prognostically important upstaging that led to an altered management strategy in 12% of 584 patients with MCC, or 1 in 8.

“You don’t want to overtreat locally a lesion that has already spread distantly; you want to start focusing on the distant disease. The local disease is secondary,” he said.

The surgical excision of the primary lesion should be thoughtfully wide without being aggressive or mutilating, and it should involve primary closure. “Definitely avoid flaps and grafts, which delay your further management with radiotherapy by months and months,” Dr. Nghiem advised.

Adjuvant radiotherapy of the primary tumor site is extremely effective at preventing recurrent MCC. In Dr. Nghiem’s view, almost everyone is a candidate: In a series of 803 patients in the Seattle MCC cohort, 92% received local adjuvant radiotherapy. The national rate, in contrast, is only about 50%, highlighting the need for additional physician education.

“A little bit of radiation – one dose – appears to be just as effective as 6 weeks in controlling microscopic disease. That’s probably something we’re going to be moving towards as a field,” he predicted.

Indeed, local adjuvant radiotherapy is so effective in MCC that the surgical margins make no difference. This was demonstrated in a study by Dr. Nghiem and his coinvestigators involving 70 patients with margins greater than 1 cm who received radiotherapy, 70 others with smaller or even positive margins who received radiotherapy, and 35 patients with margins of 1 cm or less who did not receive radiotherapy. There were no MCC recurrences in any of the radiotherapy recipients, regardless of their margin status. In contrast, 7 of the 35 patients who didn’t receive radiation therapy developed a cancer recurrence. Of note, the recurrence rate of MCC is historically about 40% – far greater than for any other skin cancer. Most recurrences happen within the first 2-3 years, Dr. Nghiem observed.

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