SAN DIEGO — 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.
Dr. 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, Dr. 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.
Ted Bosworth/MDedge News
Dr. Susan M. Swetter
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,” Dr. 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 Dr. 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 Dr. 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. Dr. Swetter said that even smaller margins can be considered “to accommodate function and/or the anatomic location.”