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Melanoma Excision Sliding Scale

<p>A sliding scale to bridge the gap between recommended 1 and 2 centimeter excision margins for melanoma.</p>

A sliding scale to bridge the gap between recommended 1 and 2 centimeter excision margins for melanoma.

While melanoma accounts for only 5% of skin cancers, it causes 75% of skin cancer deaths. Additionally, melanoma causes  morbidity and mortality in people of relatively young age, causing a loss of almost 20 years of potential life for each related death in the United States. Further, the incidence of melanoma is increasing annually.

Surgical excision is the only potentially curative treatment for primary cutaneous melanoma; however, remarkably, appropriate margins have not been thoroughly elucidated. Current randomized controlled trial evidence is lacking when it comes to optimal excision margins for primary cutaneous melanoma.

The goal of surgical excision is to remove the melanoma completely and thoroughly, including malignant cells outside the periphery of the lesion and in-transit metastases. The size of the excision performed therefore should err on the side of caution; removing more tissue rather than less when and if possible. Since risk of poor outcomes increases with depth of the melanoma, rigid adherence to one centimeter (or 2 centimeter) margins regardless of the depth does not make intuitive sense. Mitigating factors for wide excision include associated surgical morbidity, cosmetic defect, and risk of adverse sequelae.

Review of (relatively) recent randomized controlled clinical trials estimates that overall survival favors wide excision, but narrowly misses a statistically significant difference (P value 0.06). Current recommendations base excision margins on the maximum Breslow depth of the primary melanoma, defined by microscopic measurement of the greatest depth of the melanoma from the granular layer of the epidermis. National guidelines for excision margins for primary cutaneous melanoma varies from country to country, likely based on difficulty of data interpretation. For melanomas less than 1 millimeter thickness, general guidelines are a one-centimeter margin excision from the edge of the clinically observable lesion. For melanomas of 1 - 2 millimeters depth, guidelines are in the one to two centimeter margin range. There is consistent agreement that excision margins for melanoma greater than 2 millimeter depth should be two centimeters.

Since wider margins lead to a slightly greater chance of a favorable prognosis, they should be sought in areas that are surgically amenable.  Below is a recommended sliding scale for excision of melanoma in areas where functional and cosmetic considerations allow for choice of excision margins. Certainly, consideration in anatomically sensitive areas should be taken into account. And indeed, United States guidelines do allow for margin modification to accommodate individual anatomic or functional considerations.

These margins may appear somewhat aggressive, but considering the possibility of the devastating consequences of melanoma, should be considered when possible.

Depth (mm)          Excision margin (cm)

MIS and <0.1       1.0

0.1-0.19               1.1

0.2-0.39               1.2

0.4-0.59               1.3

0.6-0.79               1.4

0.8-0.99               1.5

1.0-1.19               1.6

1.2-1.39               1.7

1.4-1.59               1.8

1.6-1.79               1.9

1.8-2.0                 2.0

>2.0 mm              2.0 cm (or more)

(MIS = melanoma in situ)

There is insubstantial evidence to support excisions with greater than 2 centimeter margin (no matter the depth of the melanoma), but greater width could be considered. Additionally, a minimum excision of one centimeter and a maximum excision of 2 centimeters has been previously proposed and supported in a randomized controlled trial review (Haigh 2003).

An excellent review is:

Sladden MJ et al. Surgical excision margins for primary cutaneous melanoma (review). Cochrane database of systematic reviews 2009, issue 4.

Prior review of randomized controlled trials:

Haigh PI et al. Optimal excision margins for primary cutaneous melanoma: a systematic review and metanalysis. 2003; 46(6):419-426.

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