Don't undertreat margins of primary melanoma

Following American Academy of Dermatology (AAD) guidelines for primary cutaneous melanoma helps ensure consistent outcomes, an expert said Friday at the 74^th Annual Meeting of the American Academy of Dermatology in Washington D.C.

READ: Melanoma treatment:Surgery is not obsolete

Current AAD melanoma guidelines recommend narrow excisional biopsy that encompasses the entire breadth of the lesion, with margins sufficient to ensure the lesion is not transected.¹ Physicians may accomplish this with elliptical or punch excisions with sutures, or with disk ("scoop") excisions, the guidelines add. And partial sampling is acceptable in certain cases, such as with large tumors, tumors in facial or acral locations, and tumors with a low degree of suspicion or little clinical uncertainty.

Hensin Tsao, M.D., Ph.D.When biopsying suspicious pigmented lesions, Hensin Tsao, M.D., Ph.D., says "Try to remove the entire lesion so that no cryptic focus of melanoma remains. With either fusiform excision or disk excision, the goal is to remove the entire lesion for analysis. In terms of the definitive, or wide, resection, there might be a gap there - people might still be undertreating some melanomas in terms of margins." Dr. Tsao is professor of dermatology at Harvard Medical School and director of the Melanoma and Pigmented Lesion Center/Department of Dermatology at Massachusetts General Hospital.

ALSO READ: Skin cancer cases rise, but new treatment gives hope 

AAD guidelines recommend margins of 0.5 to 1.0 cm for melanoma in situ; 1 cm for tumors ≤ 1.0 mm thick; 1 to 2 cm for lesions 1.01 to 2.0 mm thick; and 2 cm for lesions > 2.0 mm thick. "These guidelines are consistent with guidelines recommended by other organizations such as the National Comprehensive Cancer Network. The overall goal is to have more uniform guidelines."

Ultimately, Dr. Tsao says, biopsy success rests less on the type of biopsy than the expertise of the physician.

"A skilled dermatologist can usually remove the entire lesion through any number of means,” he says. “However, if you're trying to clear the melanoma lesion but technically your margins are always less than the 2 to 3 mm recommended removal margin, there’s a greater likelihood that you will bump into the tumor's edge. If we were all trained properly, results would be more uniform."

NEXT: Margin data

Margin data

Regarding margins, a long-term follow-up study which started in 1992 in the United Kingdom compared 3 cm versus 1 cm margins in tumors more than 2 mm thick. Dr. Tsao says, "It suggested that 1 cm is inadequate for melanomas greater than 2 mm.² However, this is not relevant for contemporary practice, since the guidelines recommend 2 cm margins for this thickness stratum."

One of the first trials spearheaded by the World Health Organization compared narrow (1 cm) versus wide (3 cm) margins for melanomas up to 2 mm in thickness.

INTERESTING: Mole count may not predict melanoma risk

"There were three local recurrences in the 1 cm group but none in the 3 cm arm; all three recurrences occurred in patients with melanomas between 1.00 and 2.00 mm in thickness.³ Thus, most guidelines recommend a slightly larger margin for melanomas between 1.00 and 2.00 mm in thickness," Dr. Tsao says. Research shows slightly more local recurrence for 1 cm margins versus 3 cm margins in tumors up to 2 mm thick, he notes. But again, Dr. Tsao says, surgeons nowadays generally prefer wider margins than 1 cm.

Overall, "No study shows an overall survival benefit for wider margins versus narrow ones." Because such margins offer equivalent results, "In general, surgical margins have been reduced from earlier practice without compromising results."

READ: FDA expands Opdivo use for metastatic melanoma

Margin size exerts more impact on local control than survival, he says, because by the time the tumor is removed, melanoma cells have either spread beyond the original location or not. "Imagine a melanoma on the right thigh. It's the melanoma cell that goes to the brain, liver or lung that ultimately proves fatal. And you can never eradicate that through surgery and of the right thigh, no matter if you take 5 mm or 1 cm margins. By the time of excision, melanoma cells have either spread or not. That's the reason overall survival has rarely been impacted by studies of resection margins."

Disclosures: Dr. Tsao is on the scientific advisory board for Lubax and has received funding from the National Institutes of Health, American Skin Association and the U.S. Department of Defense, and serves as an editorial advisor for several dermatologic journals.

References

1. Bichakjian CK, Halpern AC, Johnson TM, et al. Guidelines of care for the management of primary cutaneous melanoma. American Academy of Dermatology. J Am Acad Dermatol. 2011;65(5):1032-47.

2. Hayes AJ, Maynard L, Coombes G, et al. Wide versus narrow excision margins for high-risk, primary cutaneous melanomas: long-term follow-up of survival in a randomised trial. Lancet Oncol. 2016 Jan 11. doi: 10.1016/S1470-2045(15)00482-9. [Epub ahead of print]

3. Veronesi U, Cascinelli N, Adamus J, et al. Thin stage I primary cutaneous malignant melanoma. Comparison of excision with margins of 1 or 3 cm. N Engl J Med. 1988;318(18):1159-62.