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Multicenter study affirms benefit of Mohs micrographic surgery for melanoma

Skin tissue conservation and same-day reconstruction of tumor-free margins are possible in a single-day procedure with Mohs micrographic surgery with MART-1, according to a prospective multicenter study of 562 melanomas.

“This study ... provides evidence-based guidelines for routine excision margins based on the objective measurement of subclinical extension of melanoma beyond the clinically observed border,” Patrick M. Ellison, MD, from John Boyer, MD, Inc., Honolulu, and colleagues wrote.

The study included 518 patients with 377 noninvasive melanomas and 185 invasive melanomas removed via Mohs surgery with MART-1 immunostains with frozen section processing.

Surgeons measured the margins at each stage of the surgical process. The Mohs layer specimen was processed using frozen sectioned tissue with hematoxylin and eosin and MART-1 stained sections. Positive margins were excised with an additional margin of not less than 2 mm and most typically 3 mm of normal-appearing skin. The steps were repeated until they achieved histologically tumor-free margins.

In all noninvasive melanoma, 6-mm margins achieved histological tumor clearance in 77.4% of tumors, 9-mm margins cleared in 92.1% and 12-mm margins had complete clearance in 97.1%.

To achieve 97% clearance, head/neck locations required a larger margin of 12 mm whereas 10 mm was needed in trunk/extremity locations (P < .01).

In primary invasive melanoma, 6-mm, 9-mm and 12-mm margins excised 69%, 88% and 98% of the tumors, respectively. Head/neck melanomas required 12 mm to reach 97% clearance, while 10 mm was adequate in trunk/extremity locations (P < .01).

The researchers found that preoperative tumor size and larger surgical margins were positively associated.

In recurrent noninvasive melanoma tumors, 6-mm margins met clearance in 48.6%, 9 mm had 72.9% clearance, 12 mm had 86.4% and 21 mm reached 97.3%. The 34 recurrent head/neck noninvasive melanomas required 20 mm to achieve 97% clearance while the three trunk/extremity melanomas required 9 mm.

In recurrent invasive melanoma, 12-mm margins were needed for clearance in 45.5% of tumors, 15 mm for 63.6%, 18 mm for 72.7%, 21 mm for 90.9% and 30 mm for 100%. Six head/neck tumors needed 20 mm for 97% clearance, and five trunk/extremity tumors needed 30 mm for 97% clearance.

The researchers also examined treatment cost. The overall average cost per tumor treated with Mohs micrographic surgery was $1,336.60; tumors on the trunk/extremity averaged $1,100.89, and tumors on the head/neck averaged $1,459.22.

The researchers recommended initial surgical margins of at least 10 mm for primary trunk/extremity melanomas and 12 mm for head/neck melanomas to reach histologically negative margins in most cases if comprehensive margin evaluation is not utilized.

Two limitations of the study were its nonrandomized and noncontrolled nature. – by Abigail Sutton

Disclosures: The authors report no relevant financial disclosures.