Therapeutic implications of the metabolic changes associated with BRAF inhibition in melanoma.

Melanoma metabolism can be reprogrammed by activating BRAF mutations. These mutations are present in up to 50% of cutaneous melanomas, with the most common being V600E. BRAF mutations augment glycolysis to promote macromolecular synthesis and proliferation. Prior to the development of targeted anti-BRAF therapies, these mutations were associated with accelerated clinical disease in the metastatic setting. Combination BRAF and MEK inhibition is a first line treatment option for locally advanced or metastatic melanoma harboring targetable BRAF mutations. This therapy shows excellent response rates but these responses are not durable, with almost all patients developing resistance. When BRAF mutated melanoma cells are inhibited with targeted therapies the metabolism of those cells also changes. These cells rely less on glycolysis for energy production, and instead shift to a mitochondrial phenotype with upregulated TCA cycle activity and oxidative phosphorylation. An increased dependence on glutamine utilization is exhibited to support TCA cycle substrates in this metabolic rewiring of BRAF mutated melanoma. Herein we describe the relevant core metabolic pathways modulated by BRAF inhibition. These adaptive pathways represent vulnerabilities that could be targeted to overcome resistance to BRAF inhibitors. This review evaluates current and future therapeutic strategies that target metabolic reprogramming in melanoma cells, particularly in response to BRAF inhibition.

NCCN Guidelines® Insights: Melanoma: Cutaneous, Version 2.2024.

The NCCN Guidelines for Cutaneous Melanoma (termed Melanoma: Cutaneous) provide multidisciplinary recommendations for diagnostic workup, staging, and treatment of patients. These NCCN Guidelines Insights focus on the update to neoadjuvant systemic therapy options and summarize the new clinical data evaluated by the NCCN panel for the recommended therapies in Version 2.2024 of the NCCN Guidelines for Cutaneous Melanoma.

IDH1 inhibition potentiates chemotherapy efficacy in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is associated with a five-year overall survival rate of just 13%, and development of chemotherapy resistance is nearly universal. PDAC cells overexpress wild-type IDH1 that can enable them to overcome metabolic stress, suggesting it could represent a therapeutic target in PDAC. Here, we found that anti-IDH1 therapy enhanced the efficacy of conventional chemotherapeutics. Chemotherapy treatment induced ROS and increased TCA cycle activity in PDAC cells, along with the induction of wild-type IDH1 expression as a key resistance factor. IDH1 facilitated PDAC survival following chemotherapy treatment by supporting mitochondrial function and antioxidant defense to neutralize reactive oxygen species through the generation of alpha-ketoglutarate and NADPH, respectively. Pharmacologic inhibition of wild-type IDH1 with ivosidenib synergized with conventional chemotherapeutics in vitro and potentiated the efficacy of sub-therapeutic doses of these drugs in vivo in murine PDAC models. This promising treatment approach is translatable through available and safe oral inhibitors and provides the basis of an open and accruing clinical trial testing this combination (NCT05209074).

Disparities in Receipt of Adjuvant Immunotherapy among Stage III Melanoma Patients.

OBJECTIVES: Melanoma survival has greatly improved with the advent of immunotherapy, but unequal access to these medications may exist due to nonmedical patient factors such as insurance status, educational background, and geographic proximity to treatment. METHODS: We used the National Cancer Database to assess patients with nonmetastatic cutaneous melanoma who underwent surgical resection and sentinel lymph node biopsy (SLNB) with tumor involvement from 2015 to 2020. We evaluated rates of adjuvant immunotherapy among this patient population based on patient, tumor, and facility variables, including insurance status, socioeconomic status, pathologic stage (IIIA-IIID), and treatment facility type and volume. RESULTS: Adjuvant immunotherapy was associated with improved survival for stage III melanoma, with a slight increase in 5-year OS for stage IIIA (87.9% vs. 85.9%, P=0.044) and a higher increase in stages IIIB-D disease (70.3% vs. 59.6%, P<0.001). Receipt of adjuvant immunotherapy was less likely for patients who were older, low socioeconomic status, or uninsured. Low-volume and community cancer centers had higher rates of adjuvant immunotherapy overall for all stage III patients, whereas high-volume and academic centers used adjuvant immunotherapy much less often for stage IIIA patients compared with those in stages IIIB-D. CONCLUSIONS: Our results demonstrate inconsistent use of adjuvant immunotherapy among patients with stage III melanoma despite a significant association with improved survival. Notably, there was a lower use of adjuvant immunotherapy in patients of lower SES and those treated at high-volume centers. Equity in access to novel standards of care represents an opportunity to improve outcomes for patients with melanoma.

An Age-Stratified Analysis of Early Postoperative Mortality Among Medicare-Eligible Patients With Common Gastrointestinal and Hepato-pancreato-biliary Malignancies.

Background: The frequency of major cancer surgery in the elderly (≥80 years) has increased concomitantly with the rise in average age of the population. We assessed early postoperative mortality following hepato-pancreato-biliary (HPB) and gastrointestinal (GI) procedures for common malignancies stratified by age. Methods: The National Cancer Database (2004-2017) was queried for patients who underwent resection for GI (gastroesophageal and colorectal) or HPB (pancreatic adenocarcinoma, biliary tract, and primary liver) cancers. We compared early postoperative mortality (30 d and 90 d) stratified by age (65-79 vs ≥80 years) and procedure, and compared survival outcomes by age and operative vs nonoperative management. Results: A total of 709,358 patients were included. The 30-day mortality ranged from 1.8% to 5.8% among patients 65-79 years and from 3.2% to 12.4% among patients ≥80 years depending on procedure. The 90-day mortality ranged from 3.6% to 10.6% in patients 65-79 years compared to 8.4%-21.0% among patients ≥80 years. The overall 90-day mortality was 5.2% for patients 65-79 years and 12.0% for patients ≥80 years (P < .001). Age ≥80 was associated with worse survival among operatively managed patients with each upper GI, HPB, and lower GI malignancy relative to younger patients on multivariable analysis. However, operative management of patients ≥80 years was associated with improved survival relative to nonoperative management. Discussion: Elderly patients suffer higher postoperative mortality after major GI and HPB cancer surgery, but operative management is associated with improved survival among patients ≥80 years as compared to nonoperative management. These data are important to contextualize when counseling elderly patients on their treatment options for localized GI and HPB cancers.

First-line Immunotherapy for Metastatic Merkel Cell Carcinoma: Analysis of Real-world Survival Data and Practice Patterns.

BACKGROUND: Immune checkpoint inhibitors are a promising new therapy for advanced Merkel Cell Carcinoma (MCC). We investigated real-world utilization and survival outcomes of first-line immunotherapies in a contemporary cohort. METHODS: Using the National Cancer Database (NCDB), we identified 759 patients with MCC between 2015 and 2020 with stage IV disease and known status of first-line systemic therapy. Univariable and multivariable analyses were used to determine predictors of immunotherapy usage. Overall survival (OS) was compared for patients receiving immunotherapy, chemotherapy, or no systemic therapies. RESULTS: We identified 759 patients meeting our inclusion criteria: 329 patients received immunotherapy, 161 received chemotherapy, and 269 received no systemic therapy. Adjusting for demographic, clinical, and facility factors, high facility volume significantly predicted first-line immunotherapy use (OR 1.99; P=0.017). Median OS was 16.2, 12.3, and 8.7 months, among patients who received immunotherapy, chemotherapy, or no systemic therapy, respectively (P<0.001). On Cox multivariable survival analysis, first-line immunotherapy treatment (HR=0.79, P=0.041) and treatment at high-volume centers (HR=0.58, P=0.004) were associated with improved OS. CONCLUSIONS: Consistent with clinical trial results, first-line immunotherapy associated with improvement in median overall survival for patients with stage IV MCC, significantly outperforming chemotherapy in this real-world cohort. Treatment at high-volume centers associated with first-line immunotherapy utilization suggesting that familiarity with this rare disease is important to achieving optimal outcomes for metastatic MCC.

Neoadjuvant Dual Checkpoint Inhibitors vs Anti-PD1 Therapy in High-Risk Resectable Melanoma: A Pooled Analysis.

Importance: Despite the clear potential benefits of neoadjuvant therapy, the optimal neoadjuvant regimen for patients with high-risk resectable melanoma (HRRM) is not known. Objective: To compare the safety and efficacy of dual checkpoint inhibitors with anti-programmed cell death protein-1 (anti-PD1) therapy in a neoadjuvant setting among patients with HRRM. Design, Setting, and Participants: In this pooled analysis of clinical trials, studies were selected provided they investigated immune checkpoint inhibitor treatment, were published between January 2018 and March 2023, and were phase 1, 2, or 3 clinical trials. Participant data included in the analysis were derived from trials evaluating the efficacy and safety of anti-PD1 monotherapy and the combination of anti-cytotoxic T lymphocyte-associated protein-4 with anti-PD1 in the neoadjuvant setting, specifically among patients with HRRM. Interventions: Patients were treated with either anti-PD1 monotherapy; dual checkpoint inhibition (DCPI) with a conventional dose of 3-mg/kg ipilimumab and 1-mg/kg nivolumab; or DCPI with an alternative-dose regimen of 1-mg/kg ipilimumab and 3-mg/kg nivolumab. Main Outcomes and Measures: The main outcomes were radiologic complete response (rCR), radiologic overall objective response (rOOR), and radiologic progressive disease. Also, pathologic complete response (pCR), the proportion of patients undergoing surgical resection, and occurrence of grade 3 or 4 immune-related adverse events (irAEs) were considered. Results: Among 573 patients enrolled in 6 clinical trials, neoadjuvant therapy with DCPI was associated with higher odds of achieving pCR compared with anti-PD1 monotherapy (odds ratio [OR], 3.16; P < .001). DCPI was associated with higher odds of grade 3 or 4 irAEs compared with anti-PD1 monotherapy (OR, 3.75; P < .001). When comparing the alternative-dose ipilimumab and nivolumab (IPI-NIVO) regimen with conventional-dose IPI-NIVO, no statistically significant difference in rCR, rOOR, radiologic progressive disease, or pCR was noted. However, the conventional-dose IPI-NIVO regimen was associated with increased grade 3 or 4 irAEs (OR, 4.76; P < .001). Conventional-dose IPI-NIVO was associated with greater odds of achieving improved rOOR (OR, 1.95; P = .046) and pCR (OR, 2.99; P < .001) compared with anti-PD1 monotherapy. The alternative dose of IPI-NIVO also was associated with higher odds of achieving rCR (OR, 2.55; P = .03) and pCR (OR, 3.87; P < .001) compared with anti-PD1 monotherapy. The risk for grade 3 or 4 irAEs is higher with both the conventional-dose (OR, 9.59; P < .001) and alternative-dose IPI-NIVO regimens (OR, 2.02; P = .02) compared with anti-PD1 monotherapy. Conclusion and Relevance: In this pooled analysis of 6 clinical trials, although DCPI was associated with increased likelihood of achieving pathological and radiologic responses, the associated risk for grade 3 or 4 irAEs was significantly lower with anti-PD1 monotherapy in the neoadjuvant setting for HRRM. Additionally, compared with alternative-dose IPI-NIVO, the conventional dose of IPI-NIVO was associated with increased risk for grade 3 or 4 irAEs, with no significant distinctions in radiologic or pathologic efficacy.

Disparities in the Receipt of Systemic Treatment in Metastatic Melanoma.

BACKGROUND: In 2011, immunotherapy and targeted therapy revolutionized melanoma treatment. However, inequities in their use may limit the benefits seen by certain patients. METHODS: We performed a retrospective review of patients in the National Cancer Database for patients with stage IV melanoma from 2 time periods: 2004-2010 and 2016-2020, distinguishing between those who received systemic therapy and those who did not. We investigated the rates and factors associated with treatment omission. We employed Kaplan-Meier analysis to explore the impact of treatment on overall survival. RESULTS: A total of 19,961 patients met the inclusion criteria: 7621 patients were diagnosed in 2004-2010 and 12,340 patients in 2016-2020, of whom 54.9% and 28.3% did not receive systemic treatment, respectively. The rate of "no treatment" has decreased to a plateau of ∼25% in 2020. Median overall survival was improved with treatment in both time periods (2004-2010: 8.8 vs. 5.6 mo [ P <0.05]; and 2016-2020: 25.9 vs. 4.3 mo [ P <0.05]). Nonmedical factors associated with the omission of treatment in both periods included low socioeconomic status, Medicaid or no health insurance, and treatment at low-volume centers. In the period from 2016 to 2020, patients treated at nonacademic programs were also less likely to receive treatment. CONCLUSIONS: Systemic therapies significantly improve survival for patients with metastatic melanoma, but significant disparities exist with their receipt. Local efforts are needed to ensure all patients benefit from these revolutionary treatments.

Preoperative therapy in melanoma: Evolving perspectives in clinical trials.

We reviewed phase II and III trials beginning after 2010 studying preoperative therapy in melanoma (61 trials). Compared to standard adjuvant treatment, neoadjuvant immune checkpoint inhibitors (ICIs) show improved outcomes with approximately 70-80% recurrence free survival at 2 years. Several biomarkers demonstrate predictive value for pathological response (higher PD-L1 expression) and survival (IFN-γ signatures, CD8 + cell density). A number of 'non-standard' treatment mechanisms are being studied in combination with ICI therapies such as TLR-9 agonists, and anti-LAG3 checkpoint inhibitors, which show promise for alternative therapy options in the neoadjuvant setting. Finally, trials for advanced unresectable melanomas show improved survival compared to definitive systemic treatment when upfront systemic therapies lead to resectability. To conclude, in the preoperative setting for melanoma, ICIs have potential to improve outcomes for patients, and will likely change the standard treatment approach for advanced resectable disease.

The effect of surgical timing in nonmetastatic melanoma.

BACKGROUND AND OBJECTIVES: There is no consensus guidelines on the best timing to perform Sentinel lymph node biopsy (SLNB) in high-risk melanoma patients. We aimed to understand the impact of surgical timing on nodal upstaging in patients with cutaneous melanoma. METHODS: We queried the National Cancer Database from 2004 to 2018 for patients with T2-T4, N0, M0 melanomas, who underwent melanoma excision and nodal surgery. We included patients who underwent surgery within 2-19 weeks postdiagnosis. We aimed to determine the association of surgical delay (weeks) with nodal positivity. RESULTS: A total of 53 355 patients were included, of whom 20.9% had positive lymph nodes. Patients underwent surgery at a median of 5 (4-7) weeks after diagnosis. The rate of positive nodes increased with increased weeks to surgery (line of best-fit slope = 0.38). Multivariable regression analysis identified an association between time to surgery and nodal positivity (2.4% increased risk per week, p < 0.05). Our analysis showed significantly increased likelihood of nodal positivity beginning 9 weeks after diagnosis (odds ratio [OR] = 1.3, p < 0.05). Furthermore, patients with T2-3 tumors had a significant increase in nodal positivity with increased time to surgery (OR = 1.03 per week, p < 0.001). However, no significant trend in nodal positivity was identified for patients with T4 melanomas (OR = 1.01 per week, p = 0.596). CONCLUSION: Surgery within 9 weeks of melanoma diagnosis was not associated with increased likelihood of nodal positivity. These data can guide clinical conversations regarding the importance of surgical timing for melanoma.

Is sentinel lymph node biopsy needed for lentigo maligna melanoma?

BACKGROUND AND OBJECTIVES: Sentinel lymph node biopsy (SLNB) is an area of debate in the management of lentigo maligna melanoma (LMM). The utility of SLNB and its prognostic value in LMM have not yet been studied with large databases. METHODS: We performed a retrospective review of the National Cancer Database (2012-2020) and the Surveillance, Epidemiology, and End Results (2010-2019) database for patients with cutaneous nonmetastatic LMM with Breslow thickness >1.0 mm. Multivariable logistic regression identified factors associated with SLNB performance and sentinel lymph node (SLN) positivity. Univariable and multivariable analyses assessed overall survival (OS) and melanoma-specific survival (MSS) based on SLNB performance and SLN status. RESULTS: Compared to other melanoma subtypes, LMM had lower rates of SLNB (66.6% vs. 80.0%-84.0%) and SLN positivity (11.3% vs. 18.6%-34.2%). Compared to patients who did not undergo SLNB, SLN status was significantly associated with improved OS in patients with SLN positive (HR = 0.64 [0.55-0.76]) and SLN negative (HR = 0.68 [0.49-0.94]), and worse MSS only in patients with positive SLN (HR = 3.93, p < 0.05). CONCLUSION: The improved OS associated with SLNB likely implies surgical selection bias. Analysis of MSS confirms appropriate patient selection and suggests important prognostic value associated with SLN status. These results support continued SLNB for LMM patients according to standard guidelines.

Surgical management of 1- to 2-cm neuroendocrine tumors of the appendix: Appendectomy or right hemicolectomy?

BACKGROUND: The surgical management of 1- to 2-cm neuroendocrine tumors of the appendix is an area of debate. We analyzed the clinical outcomes of appendectomy and compared them to right hemicolectomy. METHODS: We queried the National Cancer Database to identify patients treated for 1- to 2-cm ANETs from 2004 to 2018. Patients were stratified by surgical approach (appendectomy vs. hemicolectomy). Multivariable models were used to identify factors associated with the choice of surgical approach and the association between surgical approach and overall survival. RESULTS: Of the 3,189 patients we included, 1,573 (49.3%) underwent right hemicolectomy and 1,616 (50.7%) appendectomy. The appendectomy rate increased from 37.7% in 2004 to 58.9% in 2018. On multivariable analysis, patients with grade 2 and 3 tumors were less likely to undergo appendectomy alone (odds ratio = 0.41, 95% confidence interval = 0.26-0.66). Longer travel distance was associated with a higher likelihood of undergoing appendectomy (odds ratio = 2.52, 95% confidence interval = 1.15-5.51). After adjusting for tumor grade, appendectomy alone had similar survival to hemicolectomy (hazard ratio = 1.03, 95% confidence interval = 0.67-1.59). CONCLUSION: In this updated analysis of the National Cancer Database, right hemicolectomy was not associated with improved overall survival compared to appendectomy alone for 1- to 2-cm neuroendocrine tumors of the appendix. Although patients with grade 2 or 3 tumors are more likely to undergo right hemicolectomy, this procedure may not improve their treatment or overall outcome.

Trends in and Prognostic Significance of Time to Treatment in Pancreatic Cancer: A Population-Based Study.

INTRODUCTION: The association of time to treatment (TTT) with survival remains unclear in pancreatic adenocarcinoma (PDAC). In this study, we evaluate the recent trends in TTT, causes for delay, and its effect on survival. METHODS: We included patients with PDAC of all stages from the National Cancer Database (2004-2020) who underwent either surgery or chemotherapy/radiotherapy (CT/RT). TTT was defined as the duration between tissue diagnosis and first treatment. Linear regression (ß) was used to study the temporal trends in time delay. RESULTS: A total of 239,638 patients were included. The median TTT was 25 days. Using multivariable analysis, we found that increasing age (OR 1.48), female gender (OR 1.04), Black race (OR 1.3), lower educational status (OR 1.2), Medicaid, Medicare insurance, and uninsured (OR 1.2, 1.5, and 1.2, respectively), treatment at academic centers (OR 1.3), higher Charlson-Deyo comorbidity index (OR 1.2), and CT/RT (OR 1.5) were associated with increased TTT. There was a steady rise in median TTT from 21 to 28 days between 2004 and 2020 (ß = 0.3), suggestive of a worsening trend. Concurrently, there was an increasing trend in utilization of neoadjuvant CT/RT between 2004 and 2020 in early-stage PDAC. On Cox regression, TTT delay was associated with poor overall survival in stage I-IV patients (HR 1.1, 1.1, 1.09, and 1.53, respectively). CONCLUSIONS: Delayed treatment approaching 2 months was observed in 10% of the population. The rising temporal trend in TTT may be attributed to the increasing shift toward neoadjuvant CT/RT in early-stage PDAC and/or the increasing use of tissue biopsy prior to surgery.

Patient and provider factors predict non-surgical management for complex upper gastrointestinal cancers.

BACKGROUND: Surgery is the only potentially curative treatment for non-metastatic upper gastrointestinal cancers. We analyzed patient and provider characteristics associated with non-surgical management. METHODS: We queried the National Cancer Database for patients with upper gastrointestinal cancers from 2004 to 2018 who underwent surgery, refused surgery, or for whom surgery was contraindicated. Multivariate logistic regression identified factors associated with surgery being refused or contraindicated, and Kaplan-Meier curves assessed survival. RESULTS: We identified 249,813 patients based on our selection criteria-86.3% had surgery, 2.4% refused, and for 11.3%, surgery was contraindicated. Median overall survival was 48.2 months for patients who underwent surgery versus 16.3 and 9.4 months for the refusal and contraindicated groups. Medical and non-medical factors predicted both surgery refusals and contraindications, such as increasing age (odds ratio = 1.07 and 1.03, respectively, P < .001), Black race (odds ratio = 1.72 and 1.45, P < .001), comorbidities (Charlson-Deyo score 2+, odds ratio = 1.18 and 1.66, P < .001), low socioeconomic status (odds ratio = 1.70 and 1.40, P < .001), no health insurance (odds ratio = 3.26 and 2.34, P < .001), community cancer programs (odds ratio = 1.43 and 1.40, P < .001), low volume facilities (odds ratio = 1.82 and 1.52, P < .001), and stage 3 disease (odds ratio = 1.51 and 6.50, P < .001). On subset analysis (excluding patients age >70, Charlson-Deyo score 2+, and stage 3 cancer), non-medical predictors of both outcomes were similar. CONCLUSION: Refusal of and medical contraindications for surgery profoundly impact overall survival. The same factors (ie, race, socioeconomic status, hospital volume, and hospital type) predict these outcomes. These findings suggest variation and potential bias that may exist between physicians and patients discussing cancer surgery.

Adjuvant Chemotherapy Is Associated with Improved Survival for Stage III Colon Cancer When Initiated Beyond 8 Weeks.

BACKGROUND: The National Comprehensive Cancer Network (NCCN) guidelines recommend adjuvant chemotherapy (AC) within 6-8 weeks of surgical resection for patients with stage III colon cancer. However, postoperative complications or prolonged surgical recovery may affect the receipt of AC. The aim of this study was to assess the utility of AC for patients with prolonged postoperative recovery. METHODS: We queried the National Cancer Database (2010-2018) for patients with resected stage III colon cancer. Patients were categorized as having either normal or prolonged length of stay (PLOS: >7 days, 75th percentile). Multivariable Cox proportional hazard regression and logistic regressions were used to identify factors associated with overall survival and receipt of AC. RESULTS: Of the 113,387 patients included, 30,196 (26.6%) experienced PLOS. Of the 88,115 (77.7%) patients who received AC, 22,707 (25.8%) initiated AC more than 8 weeks after surgery. Patients with PLOS were less likely to receive AC (71.5% vs. 80.0%, OR: 0.72, 95%CI=0.70-0.75) and displayed inferior survival (75 vs. 116 months, HR: 1.39, 95%CI=1.36-1.43). Receipt of AC was also associated with patient factors such as high socioeconomic status, private insurance, and White race (p<0.05 for all). AC within and after 8 weeks of surgery was associated with improved survival for patients with both normal LOS and PLOS (normal LOS: <8 weeks HR: 0.56, 95% CI: 0.54-0.59, >8 weeks HR: 0.68, 95% CI: 0.65-0.71; PLOS: <8 weeks HR: 0.51, 95% CI: 0.48-0.54, >8 weeks HR: 0.63, 95% CI 0.60-0.67). AC was associated with significantly improved survival if initiated up to 15 weeks postoperatively (normal LOS: HR: 0.72, 95%CI=0.61-0.85; PLOS: HR: 0.75, 95%CI=0.62-0.90), and very few patients (<3.0%) initiated AC beyond this time. CONCLUSION: Receipt of AC for stage III colon cancer may be affected by surgical complications or otherwise prolonged recovery. Timely and even delayed AC (>8 weeks) are both associated with improved overall survival. These findings highlight the importance of delivering guideline-based systemic therapies, even after complicated surgical recovery.

Predictors of sentinel lymph node metastasis in very thin invasive melanomas.

BACKGROUND: Melanomas < 0.8 mm in Breslow depth have less than a 5% risk for nodal positivity. Nonetheless, nodal positivity is prognostic for this group. Early identification of nodal positivity may improve the outcomes for these patients. OBJECTIVES: To determine the degree to which ulceration and other high-risk features predict sentinel lymph node (SLN) positivity for very thin melanomas. METHODS: The National Cancer Database was reviewed from 2012 to 2018 for patients with melanoma with Breslow thickness < 0.8 mm. Data were analysed from 7 July 2022 through to 25 February 2023. Patients were excluded if data regarding their ulceration status or SLN biopsy (SLNB) performance were unknown. We analysed patient, tumour and health system factors for their effect on SLN positivity. Data were analysed using χ2 tests and logistic regressions. Overall survival (OS) was compared by Kaplan-Meier analyses. RESULTS: Positive nodal metastases were seen in 876 (5.0%) patients who underwent SLNB (17 692). Factors significantly associated with nodal positivity on multivariable analysis include lymphovascular invasion [odds ratio (OR) 4.5, P < 0.001], ulceration (OR 2.6, P < 0.001), mitoses (OR 2.1, P < 0.001) and nodular subtype (OR 2.1, P < 0.001). Five-year OS was 75% and 92% for patients with positive and negative SLN, respectively. CONCLUSIONS: Nodal positivity has prognostic significance for very thin melanomas. In our cohort, the rate of nodal positivity was 5% overall in these patients who underwent SLNB. Specific tumour factors (e.g. lymphovascular invasion, ulceration, mitoses, nodular subtype) were associated with higher rates of SLN metastases and should be used to guide clinicians in choosing which patients will benefit from SLNB.