After two recent clinical trials provided long-awaited new information on the role of lymph node management in patients with melanoma, a panel was formed to update the 2012 ASCO-Society of Surgical Oncology (SSO) guidelines for sentinel lymph node (SLN) biopsy. Published in December 2017, the updated ASCO-SSO guideline further defines the subset of patients with thin melanomas who may be considered for SLN biopsy and suggests the possibility of foregoing complete lymph node dissection (CLND) in selected patients with a positive sentinel node.1
Changes to SLN Recommendations
Dr. Mark Faries
Dr. Sandra L. Wong
“Patients with T1/thin melanomas represent a large fraction of patients with melanoma overall. Although only a small percentage of patients will have nodal metastases, the absolute number with metastases is substantial,” Mark Faries, MD, of the Angeles Clinic and Research Institute and guideline co-author, said. However, Dr. Faries noted that the decision to undergo SLN biopsy “is not cut and dry. It is important for clinicians to be familiar with the benefits and risks so their patients can be fully informed.”
This recommendation follows reports of slightly higher rates of metastases in patients with T1b lesions and a demonstration of improved prognosis with negative SLN biopsy among patients with thin melanomas > 0.8 mm, compared with those who do not undergo SLN biopsy. Guideline co-author Sandra L. Wong, MD, MS, of Dartmouth-Hitchcock Health System, explained that “the harmonization of the guideline recommendations with the just-implemented 8th edition of the American Joint Committee on Cancer staging system will help clinicians with clinical decision-making.”
Dr. Wong added that the new recommendations “assure appropriate use of SLN biopsy (T1b lesions), noting the importance of avoiding overuse of the procedure in patients with a very low likelihood of having regional nodal disease, e.g., T1a.”
Recommendations for patients with thicker melanomas are unchanged; SLN biopsy is still recommended for patients with intermediate-thickness T2 and T3 melanoma (> 1.0-4.0 mm thickness). For patients with thick T4 (> 4.0 mm) melanomas, guidelines recommend considering SLN biopsy. Dr. Wong noted that for these patients, SLN biopsy has “both diagnostic and therapeutic benefits for nodal staging … some patients may end up with T4N0 disease, which has different prognostic implications.” If patients are found to have involved nodes, Dr. Wong explained that this information “could influence decisions around systemic treatment, and there is reason to believe that there are regional control benefits of SLN biopsy.”
Changes to CLND Recommendations
For patients with a positive SLN biopsy, the decision to proceed to completion lymph node dissection (CLND) can be challenging. Previously, CLND was recommended for all patients with a positive SLN biopsy. However, two trials—the Multicenter Selective Lymphadenectomy II (MSLT-II) trial and the German Dermatologic Oncology Cooperative Group trials—found no difference in melanoma-specific survival with CLND versus close observation in selected patients.
Accordingly, the updated guidelines state that CLND and careful observation are both options for patients with low-risk micrometastatic disease, keeping in mind clinicopathological factors, in particular the exclusion criteria for the MSLT-II trial. Dr. Faries explained that although CLND can provide significant staging information, “the potential downsides of the procedure, including the risk of lymphedema, may lead some patients to elect observation.” On the other hand, he commented that detection of nonsentinel nodal metastases “might tip the scales for some patients who are not sure whether they want additional treatment.”
Close observation, which in both trials required ultrasound of regional nodes, presents its own challenges to patients and providers. Dr. Wong noted that developing a program for close follow-up “necessitates coordination between surgeons, radiologists, and other involved providers such as dermatologists, medical oncologists, and dermatopathologists.” Dr. Faries added that if this type of close follow-up is not possible for the patient or their physician, “they should probably go ahead with the dissection.”
For patients at higher risk of distant metastases, guidelines propose that observation should be considered “only after a thorough discussion with patients about the potential risks and benefits of foregoing CLND.” Dr. Wong suggested that for patients with a high risk of metastasis, “the risks of foregoing CLND must be discussed, since lack of survival benefit is just one clinical endpoint.”
Dr. Faries added that patients diagnosed with sentinel node metastases are often scared or overwhelmed and may need time to process the information and consider their next steps. “Each patient will weigh the risks and benefits of surgery differently, but each should be given a full opportunity to make the decision that is right for them,” he said.
–Melinda Tanzola, PhD