Sentinel node followed by completion lymph node dissection versus nodal observation: staging or therapeutic? Controversy continues despite final results of MSLT-1

Management of Localized Melanoma in the Anti-PD-1 Era

PURPOSE OF REVIEW

The management of cutaneous melanoma has rapidly progressed over the past decade following the introduction of effective systemic therapies. Given the large number of recent clinical trials which have dramatically altered the management of these patients, an updated review of the current evidence regarding the management of localized melanoma is needed.

RECENT FINDINGS

The role of effective systemic therapies in earlier stages (I-III) melanoma, both in adjuvant and neoadjuvant settings is rapidly changing the role of surgery in the management cutaneous melanoma, particularly regarding surgical safety margins for wide local excision (WLE), the role of sentinel lymph node biopsy (SLNB) and the extent of lymph node dissections. The randomized phase 2 SWOG1801 trial has demonstrated superiority of neoadjuvant-adjuvant anti-PD1 therapy in improving event-free survival by 23% at 2-years over adjuvant anti-PD-1 therapy only. Furthermore, the PRADO trial has suggested a more tailored approach both the extent of surgery as well as adjuvant therapy can safely and effectively be done, depending on the response to initial neoadjuvant immunotherapy. These results await validation and it is expected that in 2024 the phase 3 Nadina trial (NCT04949113) will definitively establish neo-adjuvant combination immunotherapy as the novel standard. This will further redefine the management of localized melanoma. The use of effective systemic therapies will continue to evolve in the next decade and, together with new emerging diagnostic and surveillance techniques, will likely reduce the extent of routine surgery for stage I-III melanoma.

Alternatives and reduced need for sentinel lymph node biopsy (SLNB) staging for melanoma

Sentinel lymph node biopsy (SLNB) has been introduced in the 1990s to identify patients who might benefit from completion lymph node dissection. Neither SLNB nor CLND improved survival, but SLNB staging did provide the best staging, above Breslow thickness and ulceration. The SLN status and SLN tumour burden were used in all trials until date looking at modern adjuvant systemic therapy with immune checkpoint inhibition (ICI) or targeted therapies (TT). Adjuvant ICI and TT are shifting towards stage II melanoma. The question is whether there is still role for SLNB in melanoma, in this day and age, and if so, how does the future look for SLNB staging? The SLN status and SLN tumour burden might be useful for a consultation to discuss the number needed to treat in a risk/benefit discussion. For stage IIB/C patients, it seems likely, however, that patients will forego a nuclear scan followed by the risk of surgical intervention and morbidity associated with SLNB if they opt to receive adjuvant therapy regardless of the SLNB result. For stage I/IIA, it is still required to detect high-risk patients who might benefit from adjuvant therapy. However, biomarkers are emerging, such as gene expression profilers (GEP), immunohistological signatures and liquid biopsies with ctDNA. There still is a role for SLNB staging in melanoma today, but we expect that the availability of therapeutic option independent of SLNB status as well as emergence of validated biomarkers to predict risk will reduce the need for SLNB staging in the upcoming decade to the point it will no longer be used.

Sentinel Node Biopsy for Head and Neck Cutaneous Melanoma

Sentinel lymph node biopsy is the most precise and accurate staging technique for malignant melanoma. This resulted from international collaborations and technical innovations across subspecialties and systematic and methodical study of real-time clinical problems. This article describes sentinel node biopsy from conception to current techniques. Indications for the procedure and evidence of its prognostic value are discussed. Controversies surrounding results of Multicenter Selective Lymphadenectomy Trial I and II and German Dermatologic Cooperative Oncology Group Selective Lymphadenectomy trial are reviewed. Head and neck melanoma is presented as a unique subsite for performing sentinel node biopsy and when considering completion cervical lymphadenectomy.

Risk factors for positive sentinel lymph nodes in head and neck melanoma - a survival analysis

Introduction

Sentinel lymph node biopsy is the gold standard procedure for head and neck cutaneous melanoma staging.

Objective

To evaluate the technical aspects, positivity and prognostic effect of the cervico-facial sentinel lymph node biopsy.

Methods

Retrospective, unicentric study. From 2009 to 2014, 49 patients with cutaneous melanoma of the head and neck underwent surgery at Instituto do Câncer do Estado de São Paulo (ICESP).

Results

Of the 49 patients, 5 had cervical metastasis at the moment of admission. Clark, Breslow and mitotic index were predictors of death. Among the 31 patients undergoing sentinel lymph node biopsy, 3 had positive sentinel lymph nodes (9.7%). Deaths were recorded in two of the cases with positive sentinel lymph nodes (66.6%), and in 5 (17.8%) of the patients with negative lymph nodes. The mean Breslow index was 11.3 mm for primary melanomas with positive sentinel lymph nodes and 4.3 mm for those with negative sentinel lymph nodes. Positivity was associated with Clark and Breslow levels. Malar location showed a protective effect on prognosis. The mean survival for patients with a mitotic index <3.5 was 181 months and 63.4 months for those with a mitotic index >3.5.

Conclusion

The frequency of positive sentinel lymph node biopsy in patients with malignant melanoma of the head and neck was lower than in other studies, although the sample consisted of individuals with advanced melanomas. The mitotic index was important for prognosis prediction.

The extent of surgery for stage III melanoma: how much is appropriate?

Since the first documented lymph node dissection in 1892, many trials have investigated the potential effect of this surgical procedure on survival in patients with melanoma. Two randomised controlled trials were unable to demonstrate improved survival with completion lymph node dissection versus nodal observation in patients with sentinel node-positive disease, although patients with larger sentinel node metastases (>1 mm) might benefit more from observation than from dissection, and could potentially be considered for adjuvant systemic therapy instead of complete dissection. Adjuvant immunotherapy with high-dose ipilimumab has led to improvements in overall survival, whereas therapy with nivolumab and pembrolizumab has improved relapse-free survival with greater safety. Furthermore, adjuvant-targeted therapy with dabrafenib and trametinib has improved survival outcomes in BRAF^V600E and BRAF^V600K-mutated melanomas. Three neoadjuvant trials have all shown high response rates, including complete responses, after short-term combination therapy with ipilimumab and nivolumab with no recurrences so far, although follow-up is still short. Despite the absence of a survival benefit with completion lymph node dissection in patients with sentinel node-positive or negative disease, the use of sentinel node staging will increase because of the introduction of effective adjuvant therapies. However, routine completion lymph node dissection for sentinel node-positive disease should be reconsidered. Accordingly, existing clinical guidelines are currently being revised. For palpable (macroscopic) nodal disease, the type and extent of surgery could be reduced if the index node can accurately predict the response and if studies show that lymph node dissection can be safely foregone in patients with a complete response. Overall, the appropriate type and extent of surgery for stage III melanoma is changing and becoming more personalised.

Risk Factors for Lymphatic and Hematogenous Dissemination in Patients With Stages I to II Cutaneous Melanoma

Importance

The lymphatic and the hematogenous pathways have been proposed for disease progression in cutaneous melanoma, but association with recurrence has not been studied separately to date.

Objective

To identify the risk factors associated with lymphatic and hematogenous metastasis.

Design, Setting, and Participants

This retrospective cohort study included 1177 patients with malignant melanoma treated at Instituto Valenciano de Oncología, València, Spain. Data were retrieved from the melanoma database from January 1, 2000, through December 31, 2015, and analyzed from June 1 to 30, 2018.

Exposure

Malignant melanoma at stages I to II.

Main Outcomes and Measures

Analyses of survival free of lymphatic and hematogenous metastasis were performed using Kaplan-Meier curves and Cox proportional hazards regression.

Results

For the 1177 patients included in the study analysis (51.1% women; median age at diagnosis, 55 years [interquartile range, 42-68 years), median follow-up was 75 months (interquartile range, 33-121 months); 108 (9.2%) developed lymphatic metastasis, and 108 (9.2%) developed hematogenous metastasis. In the multivariate analysis, being older than 55 years (hazard ratio [HR], 1.9; 95% CI, 1.2-3.1), tumor in the head/neck (HR, 1.7; 95% CI, 1.0-2.9) and acral locations (HR, 2.4; 95% CI, 1.3-4.5), greater Breslow thickness (HR for >4.00 mm, 5.4; 95% CI, 2.4-12.4), and presence of vascular invasion (HR, 3.2; 95% CI, 0.9-10.6) were associated with lymphatic spreading. Hematogenous metastasis was associated with greater Breslow thickness (HR for >4.00 mm, 10.4; 95% CI, 3.6-29.7), the absence of regression (HR, 0.1; 95% CI, 0.0-1.0), TERT promoter mutations (HR, 2.9; 95% CI, 1.5-5.7), and BRAF mutations (HR, 1.9; 95% CI, 1.1-3.6).

Conclusions and Relevance

Risk factors associated with lymphatic and hematogenous metastasis differ. Follow-up and adjuvant treatment strategies may therefore need to be adapted to individual clinical, histopathologic, and molecular characteristics.

Practice-Changing Developments in Stage III Melanoma: Surgery, Adjuvant Targeted Therapy, and Immunotherapy

In this article, we will focus on the practice-changing developments for stage III melanoma, from the use of the sentinel node (SN) biopsy to complete lymph node dissection (CLND) and upcoming adjuvant therapies. MSLT-1 (Multicenter Selective Lymphadenectomy Trial-1) was the first and only prospective randomized controlled trial to examine whether the SN biopsy has any notable melanoma-specific survival benefit (primary endpoint). MSLT-1 randomly assigned 2,001 patients to undergo either wide local excision (WLE) and an SN biopsy or WLE and nodal observation. Two prospective randomized controlled trials have examined the potential benefit for immediate CLND versus delayed CLND after sequential observation. Both the DECOG-SLT and MSLT-2 trials failed to demonstrate a notable benefit for immediate CLND; therefore, sequential follow-up with ultrasonography and a delayed CLND in the case of relapse should be considered the new standard of care. The CheckMate 238 study demonstrated a notable benefit for adjuvant nivolumab in terms of 18-month relapse-free survival (RFS) rates compared with high-dose adjuvant ipilimumab. Single-agent adjuvant BRAF inhibition has been examined and failed to improve RFS. However, the COMBI-AD study did demonstrate a substantial benefit for combination BRAF and MEK inhibition for patients with BRAF-mutated resected stage IIIA to IIIC melanoma.

A Practical Approach to the Diagnosis of Melanocytic Lesions

CONTEXT.—

Melanocytic lesions are common in routine surgical pathology. Although the majority of these lesions can be confidently diagnosed using well-established morphologic criteria, there is a significant subset of lesions that can be diagnostically difficult. These can be a source of anxiety for patients, clinicians, and pathologists, and the potential consequences of a missed diagnosis of melanoma are serious.

OBJECTIVE.—

To provide a practical approach to the diagnosis of melanocytic lesions, including classic problem areas as well as suggestions for common challenges and appropriate incorporation of ancillary molecular techniques.

DATA SOURCES.—

Literature search using PubMed and Google Scholar, incorporating numerous search terms relevant to the particular section, combined with contemporaneous texts and lessons from personal experience.

CONCLUSIONS.—

Although a subset of melanocytic lesions can be diagnostically challenging, the combination of a methodical approach to histologic assessment, knowledge of potential diagnostic pitfalls, opinions from trusted colleagues, and judicious use of ancillary techniques can help the pathologist navigate this difficult area.

Gamma probe and ultrasound guided fine needle aspiration cytology of the sentinel node (GULF) trial - overview of the literature, pilot and study protocol

BACKGROUND

Sentinel node (SN) biopsy (SNB) detects clinically occult metastases of breast cancer and melanoma in 20-30%. Wound infections, seroma and lymph edema occur in up to 10%. Targeted ultrasound (US) of the SN, (with fine needle aspiration cytology (FNAC) if appropriate) has been investigated as a minimally invasive alternative, but reported sensitivity rates are too low to replace SNB. Our hypothesis is that the use of a handheld gamma probe concomitant with US may improve sensitivity. Our aim is to provide an overview of the current literature on preoperative nodal staging of clinical N0 melanoma patients, report on a pilot, and present a study protocol for a minimally invasive alternative to the SNB: Gamma probe and Ultrasound guided Fine needle aspiration cytology of the sentinel node (GULF trial).

METHODS

The GULF trial is a multicenter open single arm observational trial. Newly diagnosed cT1b-4N0M0 cutaneous melanoma or cT1-3N0M0 breast cancer patients, aged >18 years, presenting for SNB are eligible. 120 patients will be included for preoperative targeted gamma probe guided US and FNAC of the SN. Afterwards all patients proceed to surgical SNB. Primary endpoint is the sensitivity of FNAC. Secondary endpoints include SN identification rate and the histopathological compatibility of Core Needle Biopsy and FNAC vs. SNB. Secondary endpoints were investigated in a pilot with 10 FNACs and marker placements, and 10 FNACs combined with Core Needle Biopsy.

RESULTS

A pilot in 20 patients showed that SN identification rate was 90%, supporting the feasibility of this technique.

DISCUSSION

There is broad experience with US (in combination with FNAC) prior to SNB, but sensitivity and specificity are too low to completely abandon SNB. Promising alternative techniques potentially will replace SNB in the future but more evidence is needed in the form of prospective studies. Accurate identification of the SN for US-FNAC has been proven feasible in our pilot. When adequate sensitivity can be reached, US-FNAC provides a minimally invasive alternative for the surgical SNB procedure.

TRIAL REGISTRATION

The GULF trial is registered in the Netherlands Trial Registry (NTR), ID: NRT5193 . May 1st 2015.

Surgical Management and Adjuvant Therapy for High-Risk and Metastatic Melanoma

Wide local excision is considered routine therapy after initial diagnosis of primary melanoma to reduce local recurrences, but it does not impact survival. Sentinel node staging is recommended for melanomas of intermediate thickness, but it has also not demonstrated any indisputable therapeutic effect on survival. The prognostic value of sentinel node staging has been long established and is therefore considered routine, especially in light of the eligibility criteria for adjuvant therapy (trials). Whether completion lymph node dissection after a positive sentinel node biopsy improves survival is the question of current trials. The MSLT-2 study is best powered to show a potential benefit, but it has not yet reported any data. Another study, the German DECOG study, presented at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting did not show any benefit but is criticized for the underpowered design and insufficient follow-up. There is no consensus on the use of adjuvant interferon in melanoma. This topic has been the focus of many studies with different regimens (low-, intermediate-, or high-dose and/or short- or long-term treatment). Adjuvant interferon has been shown to improve relapse-free survival but failed to improve overall survival. More recently, adjuvant ipilimumab has also demonstrated an improved relapse-free survival. Overall survival data have not yet been reported due to insufficient follow-up. Currently, studies are ongoing to analyze the use of adjuvant anti-PD-1 and molecular targeted therapies (vemurafenib, dabrafenib, and trametinib). In the absence of unambiguously positive approved agents, clinical trial participation remains a priority. This could change in the near future.

Lymph nodes and the melanoma surgeon: re-defining a long-term relationship

Surgeons now have an enhanced ability to stage patients with clinically localized cutaneous melanoma using sentinel lymph node biopsy. Despite this, the weight of clinical evidence is tilting in favor of a measured approach to pre-emptive lymph node removal. Careful consideration of whether traditional surgical approaches to the regional nodes, whether done in the name of 'staging' or pre-emptive removal of a potential site of relapse, really 'benefit' the patient is paramount for optimal care.

[Sentinel node in melanoma and breast cancer. Current considerations]

The main objectives of sentinel node (SN) biopsy is to avoid unnecessary lymphadenectomies and to identify the 20-25% of patients with occult regional metastatic involvement. This technique reduces the associated morbidity from lymphadenectomy and increases the occult lymphatic metastases identification rate by offering the pathologist the or those lymph nodes with the highest probability of containing metastatic cells. Pre-surgical lymphoscintigraphy is considered a "road map" to guide the surgeon towards the sentinel nodes and to localize unpredictable lymphatic drainage patterns. The SPECT/CT advantages include a better SN detection rate than planar images, the ability to detect SNs in difficult to interpret studies, better SN depiction, especially in sites closer to the injection site and better anatomic localization. These advantages may result in a change in the patient's clinical management both in melanoma and breast cancer. The correct SN evaluation by pathology implies a tumoral load stratification and further prognostic implication. The use of intraoperative imaging devices allows the surgeon a better surgical approach and precise SN localization. Several studies reports the added value of such devices for more sentinel nodes excision and a complete monitoring of the whole procedure. New techniques, by using fluorescent or hybrid tracers, are currently being developed.