What’s new in the latest melanoma guidelines

Among the other key points to remember about the eighth edition of AJCC:

• Tumor thickness is now measured to the nearest 0.1 mm rather than to the nearest 0.01 mm, as previously. Thus, a 0.75-mm-thick melanoma is now rounded up to 0.8 mm, while a 0.74-mm melanoma becomes a 0.7-mm tumor.
• Based upon recent evidence, tumors that are 0.8-1.0 mm thick, with or without ulceration, are now classified at T1b. So are ulcerated lesions that are less than 0.8 mm.
• Dermal mitotic rate is no longer used in staging T1 tumors, although it’s still supposed to be included in pathology reports.
• The T category definitions of primary tumors have been clarified in the eighth edition. A tumor is now classified as T0 only if there is no evidence of a primary tumor. Tx is employed when the primary tumor thickness can’t be determined, as for example when the biopsy specimen was obtained by curettage. Tis is utilized for melanoma in situ.
• The N subcategory definitions of regional nodal status have been revised. Microsatellites, clinical satellites, and in-transit metastases are now categorized as N1c, N2c, or N3c based upon the number of tumor-involved regional lymph nodes. These features are no longer defined by their size or distance from the primary tumor.

2018 NCCN melanoma guidelines

The guidelines have been revised to recommend against SLNB if a patient’s pretest probability of finding a positive SLN is less than 5%. This includes patients who have a clinical stage IA/T1a melanoma with a Breslow thickness of less than 0.8 mm without ulceration.

Courtesy RegionalDerm.com

If the pretest risk is 5%-10%, the NCCN recommends “discussing and considering” SLNB with the patient. This includes melanomas that are clinical stage IB/T1b or IB/T1a lesions less than 0.8 mm with adverse features such as a high mitotic index of at least 2 per mm², especially in a younger patient.

There is to be no SLNB in patients with microsatellites, clinical satellites, or in-transit metastases because SLN status has no prognostic significance in this situation.

Bruce Jancin/MDedge News

“You basically have already upstaged them once you have found one of these factors,” Dr. Ferris observed. “Microsatellitosis, clinical satellites, and in-transit metastases have all been shown to portend a poor prognosis, but we can’t say that one is worse than the others. So we basically lump them all together and use them in N staging based on the number of involved nodes.”

Routine ordering of prognostic genetic tests for BRAF or the multigene test panels that are now commercially available is not recommended except to guide systemic therapy or to determine if a patient is a candidate for a specific clinical trial. “Basically, there is not a place to use this information in the NCCN guidelines,” according to the dermatologist.