Double Immunohistochemical Labelling of PRAME and Melan A in Slow Mohs Biopsy Margin Assessment of Lentigo Maligna and Lentigo Maligna Melanoma.

Introduction: Lentigo maligna (LM) and lentigo maligna melanoma (LMM) predominantly affect the head and neck areas in elderly patients, presenting as challenging ill-defined pigmented lesions with indistinct borders. Surgical margin determination for complete removal remains intricate due to these characteristics. Morphological examination of surgical margins is the key form of determining successful treatment in LM/LMM and underpin the greater margin control provided through the Slow Mohs micrographic surgery (SMMS) approach. Recent assessments have explored the use of immunohistochemistry (IHC) markers, such as Preferentially Expressed Antigen in Melanoma (PRAME), to aid in LM/LMM and margin evaluation, leveraging the selectivity of PRAME labelling in malignant melanocytic neoplasms. Methods: A Novel double-labelling (DL) method incorporating both PRAME and MelanA IHC was employed to further maximise the clinical applicability of PRAME in the assessment of LM/LMM in SMMS biopsies. The evaluation involved 51 samples, comparing the results of the novel DL with respective single-labelling (SL) IHC slides. Results: The findings demonstrated a significant agreement of 96.1% between the DL method and SL slides across the tested samples. The benchmark PRAME SL exhibited a sensitivity of 91.3% in the SMMS specimens and 67.9% in histologically confirmed positive margins. Discussion: This study highlights the utility of PRAME IHC and by extension PRAME DL as an adjunctive tool in the assessment of melanocytic tumours within staged excision margins in SMMS samples.

Clinical and Histopathological Investigation of Pediatric Melanonychia: A Single-Center Retrospective Case Series.

HYPOTHESIS: The natural history of pediatric melanonychia and the necessity of biopsy for ruling out melanoma are debated in the literature. We hypothesize that there is a low rate of malignant nail pathology among pediatric patients undergoing nail bed biopsy for melanonychia. METHODS: We performed a retrospective chart review of 54 pediatric patients (age <18 years) at a single institution who presented with melanonychia and underwent nail bed biopsy from 2007 to 2022. Data points collected included patient demographics, medical history, physical exam findings, pathology reports, and clinical photos. Univariate and multivariate analyses were performed to assess for risk factors associated with high-risk pathology findings. RESULTS: The average age of melanonychia onset was 5.5 years (SD 4.4). The average age of first biopsy was 7.8 years (SD 4.3). On physical exam, 27 patients had at least four features concerning for melanoma (asymmetry, border irregularity, color heterogeneity, diameter > 1/3 of nail, evolving color, evolving diameter, Hutchinson's sign). The most common pathology diagnoses were melanocytic nevus (35%), atypical intraepidermal melanocytic proliferation (AIMP) with benign features (24%), subungual lentigo (22%), and AIMP with concerning features (17%). There were no cases of melanoma in situ or invasive malignant melanoma. On multivariate regression, the only significant risk factor associated with more concerning pathology (AIMP with concerning features) was the calendar year in which biopsy was performed (coefficient = -0.34, P = 0.016). There was no association between physical exam features and high-risk pathology. Twelve patients had surgical re-excision of the lesion, 6 of which were due to incomplete excision of AIMP with concerning features and 6 of which were due to recurrence. CONCLUSIONS: Our case series did not find any cases of melanoma in situ or malignant melanoma arising from pediatric melanonychia. Atypical intraepidermal melanocytic proliferation with concerning features was associated only with the year in which the biopsy was performed, which may reflect the improved understanding of pediatric melanonychia as often benign despite concerning features on pathology. The decision to perform a nail matrix biopsy in pediatric melanonychia should be based on a collaborative discussion between the patient's parents, dermatologist, and plastic surgeon.

Anatomical variants of the intercostobrachial nerve and its preservation during surgery, a systematic review and meta-analysis.

BACKGROUND: The anatomic variants of the intercostobrachial nerve (ICBN) represent a potential risk of injuries during surgical procedure such as axillary lymph node dissection and sentinel lymph node biopsy in breast cancer and melanoma patients. The aim of this systematic review and meta-analysis was to investigate the different origins and branching patterns of the intercostobrachial nerve also providing an analysis of the prevalence, through the analysis of the literature available up to September 2023. MATERIALS AND METHODS: The protocol for this study was registered on PROSPERO (ID: CRD42023447932), an international prospective database for reviews. The PRISMA guideline was respected throughout the meta-analysis. A systematic literature search was performed using PubMed, Scopus and Web of Science. A search was performed in grey literature through google. RESULTS: We included a total of 23 articles (1,883 patients). The prevalence of the ICBN in the axillae was 98.94%. No significant differences in prevalence were observed during the analysis of geographic subgroups or by study type (cadaveric dissections and in intraoperative dissections). Only five studies of the 23 studies reported prevalence of less than 100%. Overall, the PPE was 99.2% with 95% Cis of 98.5% and 99.7%. As expected from the near constant variance estimates, the heterogeneity was low, I2 = 44.3% (95% CI 8.9%-65.9%), Q = 39.48, p = .012. When disaggregated by evaluation type, the difference in PPEs between evaluation types was negligible. For cadaveric dissection, the PPE was 99.7% (95% CI 99.1%-100.0%) compared to 99.0% (95% CI 98.1%-99.7%). CONCLUSIONS: The prevalence of ICBN variants was very high. The dissection of the ICBN during axillary lymph-node harvesting, increases the risk of sensory disturbance. The preservation of the ICBN does not modify the oncological radicality in axillary dissection for patients with cutaneous metastatic melanoma or breast cancer. Therefore, we recommend to operate on these patients in high volume center to reduce post-procedural pain and paresthesia associated with a lack of ICBN variants recognition.

Influence of Post-radiation Ocular Surface Disorder on Ocular Surgery: A Case Report and Review of the Literature.

BACKGROUND: Ocular surface disorder after ocular radiation therapy, even though commonly reported, is often overlooked. Any delay in diagnosis may lead to complications that threaten vision. The presented case highlights the clinical outcome of a severe post-radiation disorder of the ocular surface, the importance of intensive therapy, and the limitations of further surgical interventions. CASE PRESENTATION: A 34-year-old woman was referred for a second opinion due to a years-long history of pain and redness in her right eye (OD) after proton beam therapy for recurrent iris melanoma. The patient then developed post-radiation retinopathy with macula edema, secondary glaucoma, cataract, as well as a severe ocular surface disorder with corneal decompensation and band keratopathy. Several surgical treatments have been attempted, including phacoemulsification with IOL implantation and trabeculectomy with mitomycin C. Due to refractory glaucoma, Baerveldt glaucoma drainage was then necessary. Given the worsening clinical presentation of post-radiation ocular surface disorder with progressing band keratopathy, the possibility of penetrating keratoplasty (PKP) was discussed. CONCLUSION: The continuous worsening of clinical symptoms of the disorder of the ocular surface after proton beam radiotherapy can be the result of a post-radiation syndrome. Gradual expansion of ischemia, vasculitis, and inflammatory mediators compresses the retinal tissue, leading to recurrent macular edema as well as to secondary glaucoma and corneal decompensation. Band keratopathy is occasionally noted and seems to result from severe post-radiation disorder of the ocular surface. However, PKP would typically be indicated in cases of corneal perforation, uncontrolled infectious keratitis, or for improving vision in the presence of corneal opacification, none of which applied to our patient. Furthermore, post-radiation keratopathy implies compromised corneal stromal lymphogenesis and angiogenesis, both of which are now considered essential conditions for allograft rejection. Moreover, a previously performed Baerveldt glaucoma drainage surgery can affect the survival rate of the endothelial cells of the recipient cornea. Therefore, a penetrating or endothelial keratoplasty should be viewed as a high-risk procedure. In this instance, the rigorous treatment of the severe ocular surface disorder was crucial. We managed our patient's complex situation by following the latest guidelines set by the Tear Film & Ocular Surface Society and aimed to alleviate the symptoms as effectively as possible. In conclusion, careful decision-making regarding surgical treatment options should be considered, taking into account the complexities and potential risks involved.

Radar-Guided Localization and Resection for Metastatic Nodal and Soft Tissue Melanoma: A Single-Institution Retrospective Study.

BACKGROUND: Radar-guided localization (RGL) offers a wire-free, nonradioactive surgical guidance method consisting of a small percutaneously-placed radar reflector and handheld probe. This study investigates the feasibility, timing, and outcomes of RGL for melanoma metastasectomy. METHODS: We retrospectively identified patients at our cancer center who underwent RGL resection of metastatic melanoma between December 2020-June 2023. Data pertaining to patients' melanoma history, management, reflector placement and retrieval, and follow-up was extracted from patient charts and analyzed using descriptive statistics. RESULTS: Twenty-three RGL cases were performed in patients with stage III-IV locoregional or oligometastatic disease, 10 of whom had reflectors placed prior to neoadjuvant therapy. Procedures included soft tissue nodule removals (8), index lymph node removals (13), and therapeutic lymph node dissections (2). Reflectors were located and retrieved intraoperatively in 96% of cases from a range of 2 to 282 days after placement; the last reflector was not able to be located during surgery via probe or intraoperative ultrasound. One retrieved reflector had migrated from the index lesion, thus overall success rate of reflector and associated index lesion removal was 21 of 23 (91%). All RGL-localized and retrieved index lesions that contained viable tumor (10) had microscopically negative margins. There were no complications attributable to reflector insertion and no unexpected complications of RGL surgery. CONCLUSION: In our practice, RGL is a safe and effective surgical localization method for soft tissue and nodal melanoma metastases. The inert nature of the reflector enables implantation prior to neoadjuvant therapy with utility in index lymph node removal.

There are a variety of tools available to localize melanoma that had spread to deep layers of the skin or lymph nodes that can guide surgeons to the cancer when the tumor cannot be felt. We evaluated a marker that reflects radar signals that has been studied in breast surgery but not in melanoma. The marker was placed in the tumor before surgery and was located during surgery using a handheld probe, guiding the surgeon to the correct location. An advantage of the radar-reflecting marker we studied is that since it is safe to stay in the body, it can be placed ahead of the use of cancer medications and can keep track of the tumor as it responds to treatment. In a review of 23 surgeries in which the radar-reflecting marker was used, there was one case where the marker migrated away from the tumor and one case where the marker was not able to be located. Monitoring or alternative definitive treatment was provided in each of these cases. Overall, we found the marker to be an effective tumor localization tool for surgeons and safe for patients. Other marker options available are unable or less suitable to be placed a long time in advance of surgery due to either technical or safety reasons, so the radar-reflecting marker is especially useful when it is placed in a tumor ahead of medical treatment leading up to planned surgical treatment.

Regional lymph node evaluation in pediatric conventional melanoma subtype: a single-center 10-year review.

PURPOSE: To assess the prognostic and therapeutic significance of sentinel lymph node biopsy (SLNB) and completion lymph node dissection (CLND) in pediatric conventional melanoma (CM), while evaluating potential predictive factors for outcomes. METHODS: We conducted a retrospective analysis of medical records spanning 2009-2020, focusing on patients aged 18 or younger with localized cutaneous conventional melanoma. RESULTS: Among the 33 patients, SLNB detected metastasis in 57.6% of cases, with 52.6% undergoing CLND. Positive SLN patients had higher relapse risk (HR 5.92; 95% CI 1.27-27.7; P = 0.024) but similar overall survival (HR 3.19; 95% CI 0.31-33.1, P = 0.33). No significant differences in disease-free survival (DFS) and OS were found between patients who underwent CLND and those who did not (HR 1.91; 95% CI 0.49-7.43, P = 0.35, and HR 0.52; 95% CI 0.03-8.32, P = 0.64, respectively). Univariate analysis showed age at diagnosis (P = 0.02) correlated with higher recurrence risk, with a 21% hazard increase per additional year of age. CONCLUSIONS: Positive SLN status and age at diagnosis were associated with worse DFS in CM patients. Our study did not find any prognostic or therapeutic value in CLND for pediatric melanoma. Further multicenter trials are needed to confirm our single-institution experience. LEVEL OF EVIDENCE: Level IV.

Role of Surgery in Metastatic Melanoma and Review of Melanoma Molecular Characteristics.

We aimed to review the molecular characteristics of metastatic melanoma and the role of surgery in metastasectomy for metastatic melanoma. We performed a systematic literature search on PubMed to identify relevant studies focusing on several mutations, including NRAS, BRAF, NF1, MITF, PTEN, TP53, CDKN2A, TERT, TMB, EGFR, and c-KIT. This was performed in the context of metastatic melanoma and the role of metastasectomy in the metastatic melanoma population. A comprehensive review of these molecular characteristics is presented with a focus on their prognosis and role in surgical metastasectomy.

Head and Neck Mucosal Melanoma: Where Are We Now?

PURPOSE OF REVIEW: To highlight recent and relevant treatment considerations while managing mucosal melanoma. RECENT FINDINGS: Evidence is building to support the use of targeted therapy and immunotherapy while managing mucosal melanoma. Surgical resection with postoperative radiotherapy plays a major role in managing resectable disease. Recent studies evaluate the addition of targeted, and immunotherapies with an attempt to determine the most efficacious sequence of treatment.

Effects of COVID-19 Pandemic on the Diagnosis of Melanoma and Keratinocyte Carcinomas: a Systematic Review and Meta-analysis.

Since December 2019, the COVID-19 pandemic has profoundly affected healthcare. The real effects of the COVID-19 pandemic on skin cancer are still unclear, more than 3 years later. This study aims to summarise the pandemic's impact on skin cancer diagnosis and outcome. A systematic review and meta-analysis was conducted, selecting studies comparing skin cancer diagnosis and prognosis post-pandemic with pre-pandemic data. A total of 27 papers were reviewed including 102,263 melanomas and 271,483 keratinocyte carcinomas. During the initial pandemic months (January-July 2020), melanoma surgeries dropped by 29.7% and keratinocyte carcinomas surgeries by 50.8%. Early pandemic tumours exhibited greater thickness and stage. In a long-term period beyond the initial months, melanoma surgeries decreased by 9.3%, keratinocyte carcinomas by 16.6%. No significant differences were observed in the Breslow thickness of melanomas after the start of the pandemic (mean difference 0.06, 95% confidence interval -0.46, 0.58). Melanomas operated on post-pandemic onset had an increased risk of ulceration (odds ratio 1.35, 95% confidence interval 1.22-1.50). Keratinocyte carcinomas showed increased thickness and worsened stage post-pandemic. However, studies included were mostly retrospective and cross-sectional, reporting diverse data. This review indicates that the pandemic likely caused delays in skin cancer diagnosis and treatment, potentially impacting patient outcomes.

Engineered platelet-based immune engager for tumor post-surgery treatment.

Tumor metastasis and recurrence are principal reasons for the high mortality and poor prognosis of cancers. Inefficient engagement between T cell and tumor cell, as well as the universal existence of immune checkpoints, are important factors to the limited immunological surveillance of the immune systems to tumor cells. Herein, an immune engager based on engineered platelets with CD3 antibody modification (P-aCD3) was constructed to facilitate the contact between T cell and tumor cell via providing the anchoring sites of above two cells. Combined with the immune checkpoint blockade strategy, P-aCD3 effectively enhanced T cell mediated cytotoxicity and inhibited tumor recurrence and metastasis in mice melanoma postoperative model and breast cancer model, resulting in significantly prolonged survival of mice.

Prognostic and predictive value of non-steroidal anti-inflammatory drugs in the EORTC 1325/KEYNOTE-054 phase III trial of pembrolizumab versus placebo in resected high-risk stage III melanoma.

BACKGROUND: Pain is common in patients with cancer. The World Health Organisation recommends paracetamol or non-steroidal anti-inflammatory drugs (NSAIDs) for mild pain and combined with other agents for moderate/severe pain. This study estimated associations of NSAIDs with recurrence-free survival (RFS), distant metastasis-free survival (DMFS) and the incidence of immune-related adverse events (irAEs) in high-risk patients with resected melanoma in the EORTC 1325/KEYNOTE-054 phase III clinical trial. PATIENTS AND METHODS: Patients with AJCC7 stage IIIA, IIIB or IIIC resected melanoma were randomized to receive 200 mg of adjuvant pembrolizumab (N = 514) or placebo (N = 505) 3-weekly for one year or until recurrence. As previously reported, pembrolizumab prolonged RFS and DMFS. NSAID use was defined as administration between 7 days pre-randomization and starting treatment. Multivariable Cox and Fine and Gray models were used to estimate hazard ratios (HRs) for associations of NSAIDs with RFS, DMFS and irAEs. RESULTS: Of 1019 patients randomized, 59 and 44 patients in the pembrolizumab and placebo arms, respectively, used NSAIDs. NSAIDs were not associated with RFS (HR 0.91, 95% CI 0.58-1.43) or DMFS in the pembrolizumab (HR 1.03, 95% CI 0.65-1.66) or placebo arms (for RFS, HR 0.76, 95% CI 0.48-1.20; for DMFS, HR 0.80, 95% CI 0.49-1.31). NSAIDs were associated with the incidence of irAEs in the placebo arm (HR 3.06, 95% CI 1.45-6.45) but not in the pembrolizumab arm (HR 0.94, 95% CI 0.58-1.53). CONCLUSION: NSAIDs were not associated with efficacy outcomes nor the risk of irAEs in patients with resected high-risk stage III melanoma receiving adjuvant pembrolizumab.

Mucosal melanoma of the head and neck: a retrospective analysis of 34 cases in Japan.

PURPOSE: Mucosal melanoma of the head and neck (MMHN) is a rare condition. This study aimed to investigate oncological outcomes of surgical intervention in patients with MMHN. MATERIALS AND METHODS: The study included 34 patients with MMHN who underwent surgical resection as initial treatment at 10 institutions in Japan between July 2005 and June 2015. Results: The 5-year overall survival (OS), local control rate (LCR), disease-free survival (DFS), and disease-specific survival (DSS) rates were 48.7%, 53.4%, 32.4%, and 55.1%, respectively. Based on multivariate analysis, no independent prognostic factors for the 5-year OS and DSS were found. Based on univariate analysis, the 5-year LCR was worse in patients with lesions in the nasal cavity and paranasal sinuses than in the oral cavity and pharynx. However, no differences in oncological outcomes were identified in relation to primary sites, and postoperative radiotherapy (PORT) and adjuvant systemic therapy did not contribute to improvements in the 5-year OS. CONCLUSIONS: No independent prognostic factors for the 5-year OS or DSS were identified. Regional or distant recurrences are often identified, regardless of local control with surgical resection. Difficult control of MMHN with conventional therapeutic strategies, such as surgical intervention, PORT, and systemic therapy, has been suggested.

Perioperative therapy of melanoma: Adjuvant or neoadjuvant treatment.

Surgery is the mainstay treatment of melanoma. However, even after radical resection the risk of relapses in majority of stage IIB-IV disease remains high. Currently, the standard treatment after surgery in high risk patients is systemic adjuvant therapy administered up to one year based on the results of clinical trials indicating significant reduction of risk of relapses. All clinical trials in adjuvant setting were based as primary end-point on relapse-free survival, not overall survival, and they did not incorporate and validate biomarkers prospectively. A new therapeutic strategy in locoregional advanced melanomas becomes a preoperative treatment to further increase of the cure rates and decrease the duration of systemic therapy.

Perioperative treatment with tranexamic acid in melanoma (PRIME): protocol for a Danish multicentre randomised controlled trial investigating the prognostic and treatment-related impact of the plasminogen-plasmin pathway.

INTRODUCTION: Inflammation is a hallmark of cancer and is involved in tumour growth and dissemination. However, the hallmarks of cancer are also the hallmarks of wound healing, and modulating the wound inflammatory response and immune contexture in relation to cancer surgery may represent effective targets of therapies.Repurposing anti-inflammatory drugs in a cancer setting has gained increasing interest in recent years. Interestingly, the known and thoroughly tested antifibrinolytic drug tranexamic acid reduces the risk of bleeding, but it is also suggested to play important roles in anti-inflammatory pathways, improving wound healing and affecting anti-carcinogenic mechanisms.As a novel approach, we will conduct a randomised controlled trial using perioperative treatment with tranexamic acid, aiming to prevent early relapses by >10% for patients with melanoma. METHODS AND ANALYSIS: Design: investigator-initiated parallel, two-arm, randomised, blinded, Danish multicentre superiority trial. PATIENTS: ≥T2 b melanoma and eligible for sentinel lymph node biopsy (n=1204).Project drug: tranexamic acid or placebo. TREATMENT: before surgery (intravenous 15 mg/kg) and daily (peroral 1000 mg x 3) through postoperative day 4. PRIMARY OUTCOME: relapse within 2 years after surgery.Primary analysis: risk difference between the treatment arms (χ2 test). SECONDARY OUTCOMES: postoperative complications, adverse events and survival.Inclusion period: summer 2023 to summer 2026. ETHICS AND DISSEMINATION: The trial will be initiated during the summer of 2023 and is approved by the National Committee on Health Research Ethics, the Danish Medicine Agency, and registered under the Data Protection Act. The study will be conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. Patients included in the study will adhere to normal Danish treatment protocols and standards of care, and we expect only mild and temporary side effects. Positive and negative results will be published in peer-reviewed journals, with authorships adhering to the Vancouver rules. TRIAL REGISTRATION NUMBER: NCT05899465; ClinicalTrials.gov Identifier.

An Ontario Health (Cancer Care Ontario) Clinical Practice Guideline: Surveillance Strategies in Patients with Stage I, II, III or Resectable IV Melanoma Who Were Treated with Curative Intent.

AIMS: To make recommendations on managing the surveillance of patients with stage I, II, III or resectable IV melanoma who are clinically free of disease following treatment with curative intent. MATERIALS AND METHODS: This guideline was developed by Ontario Health's (Cancer Care Ontario's) Program in Evidence-Based Care and the Melanoma Disease Site Group (including seven medical oncologists, four surgical oncologists, three dermatologists, one radiation oncologist and one patient representative). The MEDLINE, EMBASE, Cochrane Library, PROSPERO databases and the main relevant guideline websites were searched. Internal and external reviews were conducted, with final approval by the Program in Evidence-Based Care and the Melanoma Disease Site Group. The Grading of Recommendations, Assessment, Development and Evaluation approach was followed, and the Modified Delphi method was used. RESULTS: Based on the current evidence (eight eligible original study papers and four relevant guidelines) and the clinical opinions of the authors of this guideline, the initial recommendations were made. To reach 75% agreement for each recommendation, the Melanoma Disease Site Group (16 members) voted twice and one recommendation was voted on three times. After a comprehensive internal and external review process (including national and international reviewers), 12 recommendations, three weak recommendations and six qualified statements were ultimately made. CONCLUSIONS: After a systematic review, a comprehensive internal and external review process and a consensus process, the current guideline has been created. The guideline authors believe that this guideline will help clinicians, patients and policymakers make well-informed healthcare decisions that will guide them in clinical melanoma surveillance and ultimately assist in improving patient outcomes.

Optimal Practices for Suspected Nodal Melanoma-The Role of the General Surgeon.

This Viewpoint describes results of trials on neoadjuvant checkpoint inhibitor immunotherapy for patients with metastatic melanoma and recommends increased use of this approach.

The Value of Anterolateral Thigh Free Flap for the Reconstruction of Malignant Melanoma of the Sole of the Foot.

BACKGROUND: Wide excision of malignant melanoma on the foot usually results in an extensive function-destroying defect, and the reconstruction of foot defects remains challenging for reconstructive surgeons. We propose using anterolateral thigh perforator (ALT) free flaps for the reconstruction of widespread defects caused by malignant melanoma in the sole. METHODS: This retrospective study included 34 patients who underwent reconstruction of sole defects caused by malignant melanoma resection with 35 ALT perforator free flaps between August 2005 and July 2021. RESULTS: In total, 18 male patients and 16 female patients were included (mean age at surgery, 65.4 years). The mean size of the flaps was 100.4 cm 2 . Thirty-three of the 35 flaps survived. Hematoma, seroma, and chronic ulceration were not identified in any cases. All patients achieved independent ambulation within the follow-up period, except 1 patient with gait discomfort. The 5-year overall and disease-free survival rates of patients were 64.4% and 56.6%, respectively. CONCLUSIONS: The ALT flap is a versatile surgical option that should be considered for reconstruction of the sole after malignant melanoma resection, considering its various surgical advantages and the functional aspects of independent ambulation, the aesthetic aspects of wearing conventional footwear, and the anatomical aspects of the sole.

Smoking Status and Survival in Patients With Early-Stage Primary Cutaneous Melanoma.

Importance: While smoking is associated with a decreased incidence of cutaneous melanoma, the association of smoking with melanoma progression and death is not well defined. Objective: To determine the association of smoking with survival in patients with early-stage primary cutaneous melanoma. Design, Setting, and Participants: This cohort study performed a post hoc analysis of data derived from the randomized, multinational first and second Multicenter Selective Lymphadenectomy Trials (MSLT-I and MSLT-II). Participants were accrued for MSLT-I from January 20, 1994, to March 29, 2002; MSLT-II, from December 21, 2004, to March 31, 2014. Median follow-up was 110.0 (IQR, 53.4-120.0) months for MSLT-I and 67.6 (IQR, 25.8-110.2) months for MSLT-II. Patients aged 18 to 75 years with clinical stages I or II melanoma with a Breslow thickness of 1.00 mm or greater or Clark level IV to V and available standard prognostic and smoking data were included. Analyses were performed from October 4, 2022, to March 31, 2023. Exposure: Current, former, and never smoking. Main Outcomes and Measures: Melanoma-specific survival of patients with current, former, and never smoking status was assessed for the entire cohort and for nodal observation and among subgroups with sentinel lymph node biopsy (SLNB)-negative and SLNB-positive findings. Results: Of 6279 included patients, 3635 (57.9%) were men, and mean (SD) age was 52.7 (13.4) years. The most common tumor location was an extremity (2743 [43.7%]), and mean (SD) Breslow thickness was 2.44 (2.06) mm. Smoking status included 1077 (17.2%) current, 1694 (27.0%) former, and 3508 (55.9%) never. Median follow-up was 78.4 (IQR, 30.5-119.6) months. Current smoking was associated with male sex, younger age, trunk site, thicker tumors, tumor ulceration, and SLNB positivity. Current smoking was associated with a greater risk of melanoma-associated death by multivariable analysis for the entire study (hazard ratio [HR], 1.48 [95% CI, 1.26-1.75]; P < .001). Former smoking was not. The increased risk of melanoma-specific mortality associated with current smoking was greatest for patients with SLNB-negative melanoma (HR, 1.85 [95% CI, 1.35-2.52]; P < .001), but also present for patients with SLNB-positive melanoma (HR, 1.29 [95% CI, 1.04-1.59]; P = .02) and nodal observation (HR, 1.68 [95% CI, 1.09-2.61]; P = .02). Smoking at least 20 cigarettes/d doubled the risk of death due to melanoma for patients with SLNB-negative disease (HR, 2.06 [95% CI, 1.36-3.13]; P < .001). Conclusions and Relevance: The findings of this cohort study suggest that patients with clinical stage I and II melanoma who smoked had a significantly increased risk of death due to melanoma. Smoking status should be assessed at time of melanoma diagnosis and may be considered a risk factor for disease progression.