New NCCN Melanoma Guidelines Capture Evolving Best Practice

New NCCN Melanoma Guidelines Capture Evolving Best Practice

SAN DIEGO — New guidelines for cutaneous melanoma have been issued by the National Comprehensive Cancer Network (NCCN), creating some new standards of practice that extend a slow divergence from the last set of detailed recommendations released by the American Academy of Dermatology (AAD) in 2019.

Based on the constantly evolving science that drives guidelines, the new set of NCCN recommendations reflects the latest iteration of a consensus effort to define best practice, according to Susan M. Swetter, MD, professor of dermatology and director of the Pigmented Lesion and Melanoma Program at Stanford University in California.

Swetter chaired the committee that developed the most recent NCCN guidelines, released February 12. She also chaired the work group that developed the AAD recommendations, released in 2019. Differences between the two primarily reflect evolving evidence and expert opinion over time. 

Next AAD Guidelines More Than 1 Year Away

The AAD guidelines are developed infrequently and in a process that can take years. The next AAD cutaneous melanoma guidelines are not likely to be released until the end of 2025 or in 2026, Swetter said at the annual meeting of the American Academy of Dermatology on March 8. In contrast, the NCCN guidelines for cutaneous melanoma are revisited frequently. The last iteration was published only 1 year ago. 

Many of the changes in the 2024 NCCN guidelines capture incremental advances rather than a radical departure from previous practice. One example involves shave biopsies. According to a new recommendation, residual pigment or tumor found at the base of a shave procedure, whether for tumor removal or biopsy, should prompt a deeper punch or elliptical biopsy. 

The additional biopsy “should be performed immediately and submitted in a separate container to the pathologist,” Swetter said.

Further, the biopsy should be accompanied with a note to the pathologist that the shave specimen was transected. She added that the Breslow thickness (the measurement of the depth of the melanoma from the top of the granular layer down to the deepest point of the tumor) can accompany each of the two tissue specimens submitted to the pathologist.

This update — like most of the NCCN guidelines — is a category 2A recommendation. Category 1 recommendations signal a high level of evidence, such as a multicenter randomized trial. A 2A recommendation is based on nondefinitive evidence, but it does represent near uniform (≥ 85% agreement) expert consensus. 

More Than 50% Consensus Generally Required

The NCCN committee that issues periodic guidelines on cutaneous melanoma is formed by a rotating group of interdisciplinary melanoma specialists. More than 30 academic institutions nationwide are generally represented, and the group includes patient advocates. Typically, no comment or recommendation is provided if the committee cannot generate at least a majority endorsement (≥ 50%) on a given topic.

Overall, the majority of guidelines, including those issued by the NCCN and the AAD, are aligned, except to the degree of the time lag that provides different sets of evidence to consider. The rationale for keeping abreast of the NCCN recommendations is that updates are more frequent, according to Swetter, who noted that these are available for free once a user has registered on the NCCN website. 

Importantly, guidelines not only identify what further steps can be taken to improve diagnostic accuracy or outcomes but what practices can be abandoned to improve the benefit-to-risk ratio. As an example, surgical margins for primary melanomas have been becoming progressively smaller on the basis of evidence that larger margins increase morbidity without improving outcomes.

Although Swetter acknowledged that “we still haven’t identified the narrowest, most efficacious margins for cutaneous melanoma,” she cited studies now suggesting that margins of 2 cm appear to be sufficient even for advanced T3 and T4 tumors. Prior to the 1970s, margins of 5 cm or greater were common.

There are still many unanswered questions about optimal margins, but the 2023 NCCN guidelines already called for surgical margins of at least 1 cm and no more than 2 cm for large invasive melanomas when clinically measured around the primary tumor. Swetter said that even smaller margins can be considered “to accommodate function and/or the anatomic location.”

Best Margins for MIS Undefined

So far, there are no randomized trials yet to guide surgical margins or depth for many melanoma subtypes, including melanoma in situ (MIS). These are the types of data, when they become available, that change guidelines.

The list of procedures often performed, but for which there is no specific guidance from NCCN or other organizations, is long. Numerous examples were provided during the AAD symposium on guidelines, during which Swetter spoke. The bedside diagnosis of cutaneous melanoma with noninvasive testing was one.

Describing the 2-gene molecular assay for the evaluation of a suspected melanoma, Caroline C. Kim, MD, director of the Melanoma and Pigmented Lesion Program at Tufts University in Boston, explained that this tool, which is based on the presence of the LINC00158 gene and the preferentially expressed antigen in melanoma (PRAME), has limited utility as a tool for establishing a diagnosis of melanoma. But, she said, it has reasonably good reliability for ruling out melanoma, thereby providing a basis to avoid or delay further diagnostic steps, such as biopsy.

Skin biopsy, as established in the guidelines, “is still the gold standard,” but there are numerous studies indicating that patients negative for both LINC00158 and PRAME have a low risk for melanoma, she said.

“A double negative result is not 100% effective, but it is high,” said Kim, who provided several examples whereby she employed the test to follow the patient rather than do invasive testing.

This test is gaining popularity, according to Kim, who cited several surveys suggesting growing use among clinicians, but she characterized it as an adjunctive approach that should be considered in the context of guidelines. It is an example of an approach that is not yet standard practice but can be helpful if used appropriately, she noted.

Swetter and Kim report no relevant financial relationships. 

Ted Bosworth is a medical journalist based in New York City. 

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