Thick Primary Melanomas Research Articles

The Impact of Clinical and Histopathological Factors on Disease Progression and Survival in Thick Cutaneous Melanomas.

Thick cutaneous melanomas (Breslow depth > 4 mm) are locally advanced tumors, generally associated with poor prognosis. Nevertheless, these tumors sometimes display unpredictable behavior. This study aims to analyze clinical and histopathological features that can influence the prognosis of thick melanomas. This is a retrospective study on 94 thick primary cutaneous melanomas diagnosed between 2012 and 2018 that were followed-up for at least five years to assess disease progression and survival. We evaluated the age, gender, tumor location, histological subtype, Breslow depth, Clark level, resection margins, mitotic index, the presence/absence of ulceration, necrosis, regression, microsatellites, neurotropism, lymphovascular invasion, and the pattern of tumor-infiltrating lymphocytes, and their association with disease progression and survival. By conducting univariate analysis, we found that progression-free survival (PFS) was significantly associated with female gender, the superficial spreading melanoma (SSM) subtype, mitotic index, necrosis, microsatellites, and perineural invasion. Overall survival (OS) was significantly associated with female gender, Breslow depth, SSM subtype, necrosis, microsatellites, and perineural invasion. Through multivariate Cox proportional hazards regression, we found that the only factors associated with PFS were Breslow depth, necrosis, microsatellites, and perineural invasion, while the factors associated with OS were Breslow depth, necrosis, microsatellites, and perineural invasion. Certain histopathological features such as Breslow depth, necrosis, microsatellites, and perineural invasion could explain differences in disease evolution. This is one of the first studies to demonstrate an association between necrosis and perineural invasion and outcomes in patients with thick melanomas. By identifying high-risk patients, personalized therapy can be provided for improved prognosis.

Prognostic significance of sentinel lymph node biopsy in thick primary melanomas (>4mm)

Prognostic significance of sentinel lymph node biopsy in thick primary melanomas (>4mm)

No association between physical activity and primary melanoma thickness in a cohort of Norwegian women.

‘In a cohort of Norwegian woman aged 30–75 years at recruitment, we investigated the association between physical activity and melanoma thickness at diagnosis, the most important prognostic factor for localized primary melanoma survival. We concluded that physical activity is unlikely to be associated with melanoma thickness.’

59 Associations of Biological Sex with Clinicopathologic Features of Cutaneous Melanoma

Abstract Aim It is commonly known that women have better prognosis than men after diagnosis of primary cutaneous melanoma. However, few studies have investigated whether histopathological prognostic factors are associated with this difference. This study aimed to investigate if there were sex-specific differences in prognostic features of primary melanoma at time of diagnosis in a large clinical series. Method This was a records-based observational study of unselected patients treated for melanoma in a major tertiary oncology centre in the United Kingdoms, 2002–2016. Prognostic features (age at diagnosis; thickness of primary melanoma; ulceration and mitotic count) were extracted from histological reports and sex-specific differences tested for significance using X2 test. Results Among 1323 melanoma patients of median age 61 years (range 15–99), and roughly equal proportions of males (640, 48%) and females (683,52%), females had significantly earlier age of presentation on average than males (58 vs 64 years) (p<0.001). Comparing Breslow thickness of <2mm vs ≥2mm, significantly more females (414, 67%) than males (282, 55%) had melanomas <2mm (p<0.001). Other key histopathological factors namely presence of ulceration (p=0.073) and mitotic rate (p=0.618) were not significantly different by sex. Conclusions We found that female melanoma patients presented at an earlier age and with thinner primary melanomas than males, but mitotic rate (speed of tumour growth) was not significantly different. These data suggest that females’ better prognosis is explained by their tendency to present earlier with suspicious skin lesions than males.

Diet quality is associated with primary melanoma thickness.

BackgroundPatients' diets can influence the outcome of several common cancers, but the effect on melanoma prognosis is unknown.ObjectiveTo assess the association between quality of melanoma patients' prediagnosis diets and primary tumour thickness, the main prognostic indicator for melanoma.MethodsWe used baseline data from patients newly diagnosed with tumour stage Ib to IV cutaneous melanoma, with completed questionnaires about food intake in the past year and other factors. Diet quality was measured by the Healthy Eating Index (HEI) and melanoma thickness was extracted from histopathology reports. We estimated prevalence ratios (PRadj) and 95% confidence intervals (CIs) adjusted for confounding factors using Poisson regression models to assess associations between HEI scores and melanoma thickness.ResultsOf 634 study patients, 238 (38%) had melanomas >2 mm thick at diagnosis. Patients with the highest HEI scores were significantly less likely to be diagnosed with thick melanoma than patients with lowest HEI scores (PRadj 0.93, 95% CI 0.86–0.99) (Ptrend = 0.03). There was no evidence of effect modification by age, sex, previous melanoma or comorbidities.ConclusionsMelanoma thickness at diagnosis is significantly associated with quality of patients' diets before diagnosis.

The prognostic value of the interferon-gamma (IFNγ) signature in patients with macroscopic stage III melanoma treated with and without adjuvant systemic therapy.

9579 Background: Recently, trials have shown the benefit of adjuvant aPD-1 therapy in macroscopic stage III melanoma patients. This treatment has been incorporated in daily clinical practice, however, a substantial part of patients still does not benefit from this therapy, as they develop recurrences. The aim of this study is to evaluate the results of adjuvant aPD-1 therapy and the potency of the IFNγ signature as a prognostic or predictive marker, as it has proven to be predictive of response in neoadjuvant trials. Methods: Patients participating in an ongoing biobank study and naïve for systemic therapy were included, between 10-2017 and 06-2020, after complete resection of macroscopic stage III melanoma. Approval and reimbursement of adjuvant therapy in the Netherlands started in 12-2018, resulting in 2 cohorts of similar high risk patients: prior to availability of adjuvant aPD-1 (cohort A) and thereafter (cohort B). Data cut-off for clinical data was January 1st 2021. Transcriptome sequencing was performed on samples of stage III melanoma by CeGaT GmbH, IFNγ signature was determined on these data with the median as cut-off. Clinical data were compared between cohort A and B as intention-to-treat population, including patients with a recurrence before adjuvant therapy start (n=10). Results: In total, 99 patients were included: 50 in cohort A and 49 in cohort B. Majority of included patients had thick primary melanomas (Breslow >2mm in 59.6%) and stage IIIC/IIID disease (83.3%) according to AJCC 8th edition. At a median follow-up of 20.6 months (95% confidence interval [CI] 16.6-24.7), median recurrence-free survival (RFS) was 6.1 months (95%CI 3.9-8.4) versus 22.8 months (95%CI 8.7-36.9), significantly in favor of cohort B (p=0.011). Median overall survival (OS) was not reached in both patient groups, but was overall significantly different (p=0.040), favoring cohort B. RNA sequencing was performed in 25 patients who received adjuvant therapy and in 24 who did not, excluding patients with an early recurrence (<12 weeks). In both treatment groups median (p=0.003) and 12-months RFS (p<0.001) was significantly higher for IFNγ high patients, but both IFNγ low and high patients show higher RFS rates when receiving adjuvant aPD-1 therapy (Table). Conclusions: Our study confirms RFS and OS benefit of adjuvant aPD-1 for patients with macroscopic stage III melanoma. IFNγ has shown to be a prognostic marker in both patients who were and were not treated with adjuvant therapy, as both patients with IFNγ high and low signatures show benefit from adjuvant therapy.[Table: see text]

Shave biopsy of pediatric melanocytic tumors compromises staging and therapy planning.

e21576 Background: Melanoma is the dominant skin cancer of pediatric patients, and accounts for 1-3% of pediatric malignancies. The prognosis for both adults and children with melanoma correlates with stage at diagnosis, and initial Breslow depth is a critical determinant. Kaplan-Meier melanoma-specific survival curves show survival rates ranging from 98% (T1a) to 75% (T4b) at 10 years for adult patients with stage I and II disease at diagnosis. Pediatric patients are known to present with thicker primary melanomas as compared to their adult counterparts. The preferred biopsy method of the American Academy is Dermatology for melanoma is excisional, however partial shave biopsy is most frequently performed in children, given its simplicity, efficiency, and often low clinical suspicion for cutaneous malignancy. Despite the ease of this biopsy technique, shave biopsy has a high rate of base transection, reducing accuracy of microstaging, which is crucial for therapy planning. Methods: Retrospective chart review evaluation of the potential effects of biopsy method on staging, surgical recommendations, and treatment approach for pediatric patients with melanocytic tumors. Results: Data was available for 91 pediatric patients with a spectrum of melanocytic tumors ranging from atypical with unknown malignant potential, to melanoma. Patient characteristics including gender, age at biopsy, biopsy method, status of biopsy margins, recommendations for re-excision, sentinel lymph node biopsy, and treatment plan were collected and analyzed. There were 48 females and 43 males with age range 1—22 years (mean 10 years). Sixty-eight of 91 (75%) tumors had a positive margin (deep, peripheral, or both) on diagnostic biopsy, 52/68 (76.5%) were obtained using shave method. Evaluating the deep margin specifically, 50/91 (55%) tumors had a positive deep margin, 46/50 (92%) of which were obtained using shave method. No tumor evaluated by punch had a positive deep margin (0/18). Of all shave biopsies, 77% had positive deep margin as opposed to only 13% using alternative biopsy methods. In 10/91 (11%) patients, surgical recommendations were changed based on inaccurate microstaging and positive deep biopsy margins, 9/10 (90%) of these patients had undergone shave biopsy. Most (8/10) patients had melanoma, the remaining 2/10 had highly atypical spitzoid tumors in which melanoma could not be ruled out. Conclusions: Pediatric patients with melanocytic tumors most commonly underwent shave biopsy as the initial diagnostic biopsy method. This method of biopsy was associated with higher incidence of positive margins at diagnosis and more aggressive definitive surgical management. These findings suggest that more routine use of excisional biopsy in pediatric patients with lesions being evaluated for malignancy could decrease the incidence of inaccurate microstaging and reduce the need for more aggressive definitive surgical management.

Vascular endothelial growth factor/semaphorin-3A ratio and SEMA3A expression in cutaneous malignant melanoma.

Breslow thickness and Clark level are still important factors for cutaneous melanoma, but do not provide a precise prognosis in all cases. It is necessary to find new factors capable of a more accurate prediction of the tumor course. Angiogenesis is essential for tumor development and progression and is regulated by vascular endothelial growth factor A (VEGF-A) and semaphorins (SEMA), in particular, SEMA3A inhibits angiogenesis by affecting VEGF signaling. However, the prognostic role of angiogenetic factors remains unclear. To date, no information is available on SEMA3A in human melanoma. Microvessel density, immunohistochemical and mRNA VEGF and SEMA3A expression level in 60 thin (Breslow thickness ≤ 1.0 mm), 60 intermediate (1.1-4.0 mm) and 50 thick (>4.0 mm) primary human cutaneous melanomas were investigated and related to clinical/pathological parameters and disease-specific survival. No positive association between Breslow thickness, Clark level, metastasis presence and survival was identified; Clark level was poorly related to survival. VEGF and microvessel density were significantly higher in intermediate and thick melanomas and related to Breslow thickness and Clark level but not to metastasis status and survival. On the contrary, SEMA3A was significantly reduced in intermediate and thick melanomas and associated to metastasis and poor survival. VEGF/SEMA3A ratio was higher in the worst prognosis, resulting the most closely related factor with metastasis and survival. SEMA3A expression and VEGF/SEMA3A ratio turned out to be valuable prognostic biomarkers in patients affected by cutaneous melanoma, in particular with Breslow thickness >1 mm. SEMA3A might serve as a candidate tumor suppressor in cutaneous melanoma therapy.

The value of lymph node ultrasound and whole body PET/CT in stage IIB/C patients prior to SLNB.

e22079 Background: Stage IIB/IIC (pT3b-T4N0) patients are known to have high-risk primary tumors, even higher risk than some stage IIIA/B melanomas (AJCC Staging System 8th edition), however they follow the same routine to sentinel lymph node biopsy (SLNB) as more low-risk tumors. A priori the risk of finding SLNB or other metastases is much higher for these thick and/or ulcerated primary melanomas compared to the thinner ones. Guidelines are not conclusive regarding the use of preoperative imaging in these cases. Recently, a trend to more frequently use cross-sectional imaging has been noticed. However, others have previously shown that preoperative ultrasound was the most sensitive. The aim of this pilot study was to assess the value of ultrasound (US) and Positron Emission Tomography/Computerized Tomography (PET/CT) prior to SLNB for stage IIB/C (pT3b-T4N0) melanoma patients. Methods: Starting 2019-04, all patients with a pT3b melanoma or higher (8th AJCC) were included. All patients underwent US and PET/CT before their planned lymphoscintigraphy and routine SLNB. Suspected metastases were confirmed with cytologic puncture. Results: A total of 20 patients were screened. Seven patients (35%) had metastases detected by imaging: one by PET/CT, three by US and three by both imaging modalities. Three of these metastases were detected by US as well as PET/CT. All metastases were nodal. For all seven patients treatment was altered to lymph node dissection with adjuvant therapy. Of the 13 patients in whom no metastases were identified by imaging, six (46%) still had a positive sentinel node (SN). Conclusions: This study showed that this select group of patients had a high risk of metastases prior to SLNB and that all recurrences except one, were detected by ultrasound. This suggests that nodal staging with US is sufficient and can replace the need for SLNB when metastases is proven with cytology. Despite negative imaging, SLNB cannot be foregone for pT3b-pT4N0 melanoma patients, as many still have an involved SN. Cross-sectional imaging can be reserved for patients after positive cytology or SN to confirm the absence of distant visceral metastases.

2-cm versus 4-cm surgical excision margin for thick (>2 mm) primary malignant melanoma: long-term follow-up of a multicenter randomized trial

Background: Historically, wider excision margins as compared to today have been recommended for primary localized cutaneous melanoma (CM). With time less extensive surgery has become more established, although evidence to support this approach has been challenged. Consequently, surgical management guidelines vary worldwide, and excision margins differ from 1-3 cm for primary CMs with > 2 mm tumor thickness. Currently, for thick tumors the British recommendations suggest a more extensive approach (2-3 cm excision margin) whereas, Australian guidelines suggest a less extensive approach (1-2 cm excision margin). These discrepancies may reflect lack of evidence when agreeing on national and international recommendations for surgical management of primary CMs. Several randomized controlled trials (RCTs) have addressed the issue of appropriate margins for localized CM >2 mm in tumor thickness. Recently some doubts have been expressed in a RCT follow-up that a small excision margins would influence survival in a negative way. In meta-analysis studies it has also been highlighted that more evidence is needed.

Cutaneous melanoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up†.

Cutaneous melanoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up†.

MiRNAs as Potential Prognostic Biomarkers for Metastasis in Thin and Thick Primary Cutaneous Melanomas.

The identification of novel prognostic biomarkers for melanoma metastasis is essential to improve patient outcomes. To this aim, we characterized miRNA expression profiles in relation to metastasis in melanoma and correlated miRNAs expression with clinical-pathological factors. MiR-145-5p, miR-150-5p, miR-182-5p, miR-203-3p, miR-205-5p and miR-211-5p expression levels were analyzed in primary cutaneous melanomas, including thin and thick melanomas, and in melanoma metastases by quantitative Real-Time PCR. A significantly lower miR-205-5p expression was found in metastases compared to primary melanomas. Furthermore, a progressive down-regulation of miR-205-5p expression was observed from loco-regional to distant metastasis. Significantly lower miR-145-5p and miR-203-3p expression levels were found in cases with Breslow thickness >1 mm, high Clark level, ulceration and mitotic rate ≥1/mm2 Conclusion: Our findings point to miR-205-5p as potential biomarker of distant metastases and to miR-145-5p and miR-203-3p as markers of aggressiveness in melanoma.

Sentinel Lymph Node Biopsy in Patients With Thick Primary Cutaneous Melanoma.

BackgroundThe clinical value of sentinel lymph node biopsy (SLNB) in patients with thick melanoma is uncertain. The purpose of this study was to investigate the correlations between survival and lymph node status in thick melanomas.MethodsOf a total of 736 melanoma patients registered between 2000 and 2016, 50 presented with thick melanomas (≥ 4.0 mm) without distant metastatic disease. All patients were examined with a whole-body magnetic resonance imaging, or computed tomography, and positron emission tomography-computed tomography depending on the incorporation of the new technology in our medical institutions. They were studied according to the following procedure: 1) preoperative determination of regional lymph node along with the estimation and localization of sentinel lymph node (SLN) (dynamic isotope lymphography); 2) intraoperative localization and SLNB (lymphatic mapping); and 3) histopathology. Patient and tumor features were collected.ResultsMean follow-up was 40 months, and 37% had a follow-up ≥ 5 years. A positive SLN was identified in 28 patients (56%). No significant difference in melanoma-specific overall survival was observed in terms of the primary tumor site. Hazard ratios (HRs) were statistically significant for SLNB-positive group and mitotic rate (MR) > 3 mm2, but not for presence of ulceration. Mortality risk in the SLN-positive group was almost fourfold greater than that in the SLN-negative group at any time of follow-up.ConclusionsSLN status, along with MR, can provide valuable prognostic information in patients with thick primary cutaneous melanoma.

Abstract NG07: Genomic and transcriptomic analysis reveals incremental disruption of key signaling pathways during melanoma evolution

Abstract Thousands of tumors have been sequenced through large-scale genomic profiling efforts, and from these studies the mutational drivers of most tumor subtypes have been catalogued. Nevertheless, the order in which these mutations occur is poorly understood. This is because most tumors are sequenced at a late stage, revealing only the aftermaths of the evolutionary processes that led to their transformation. A better understanding of tumor evolution would reveal biomarkers for progression and identify crucial steps in tumorigenesis, which could be subject to future treatments. In order to delineate the evolution of melanoma, we identified cases of melanomas that were adjacent to their intact, remnant precursors (e.g. a melanoma adjacent to a nevus from which it originated). We separately microdissected the precursor and descendent areas from these cases and performed matched DNA- and RNA- sequencing on the microdissected tissues. From these data, we were able to infer the order of genetic alterations that occur during the evolution of each melanoma and the transcriptomic changes that accompanied these mutations. In total, we analyzed 230 histopathologically distinct areas (normal, precursor, and descendent tissues) from 82 patients. Somatic alterations known to activate MAP-kinase signaling occurred at the earliest stages and continued to accumulate as individual tumors evolved, indicating that MAPK signaling ramps up during progression. TERT promoter mutations were detectable in 52% of intermediate stage lesions and 85% of melanomas, regardless of tumor thickness. Telomerase expression strongly correlated with the presence of a promoter mutation, confirming that telomerase is upregulated early during progression. The transition from the benign to the malignant state was marked by the emergence of mutations affecting genes involved in chromatin remodeling and accompanied by downregulation of genes modulated by polycomb repressive complex-2 (PRC2). Mono-allelic inactivation of G1/S checkpoint genes were occasionally found in earlier histopathologic stages, whereas bi-allelic alterations, predicted to ablate checkpoint function, occurred at or after the transition to invasive melanoma. p53- and PI3-kinase pathway mutations appeared later, only becoming evident in thicker primary melanomas. Comparisons between paired primary melanomas and metastases did not reveal oncogenic alterations specifically associated with metastatic progression. The types of somatic alterations further revealed the mutational forces that shaped each melanoma during its progression. Point mutations with signatures of UV-radiation induced DNA damage were more common in the trunks of the phylogenetic trees and tended to occur prior to the transition to invasive melanoma. In contrast, copy number alterations were more branchial and tended to occur at or after the transition to invasive melanoma. In aggregate, these patterns indicate that UV radiation is the predominant mutagen shaping melanocytic neoplasms until the transition to invasive melanoma, at which point chromosomal instability prevails. Overall, this study delineates the sequential order in which key signaling pathways are disrupted during melanoma evolution, highlighting replicative senescence, G1/S arrest, and chromatin organization as barriers that have to be overcome for the transition to melanoma, whereas amplification of MAPK signaling and inactivation of the p53 and PI3-kinase pathways are associated with the progression to more advanced primaries. Citation Format: A. Hunter Shain, Nancy M. Joseph, Richard Yu, Jamal Benhamida, Shanshan Liu, Tarl Prow, Beth Ruben, Jeffrey North, Laura Pincus, Iwei Yeh, Robert Judson, Boris C. Bastian. Genomic and transcriptomic analysis reveals incremental disruption of key signaling pathways during melanoma evolution [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr NG07.

Association between Ki-67 expression and clinical outcomes among patients with clinically node-negative, thick primary melanoma who underwent nodal staging.

Patients with thick primary melanomas (≥4 mm) have highly variable survival outcomes. Cell proliferation marker Ki-67 has been identified as promising biomarker in thick melanoma but has not been evaluated since the wide spread adoption of sentinel lymph node biopsy. We revisit its prognostic relevance in the sentinel node era. We studied patients with thick (≥4 mm) primary melanoma prospectively enrolled in a clinicopathological biospecimen database from 2002 to 2015, and evaluated the prognostic value of Ki-67 expression while controlling for features included in the existing staging criteria. We analyzed 68 patients who underwent lymph node sampling and who had an available tumor for Ki-67 immunohistochemical (IHC) staining. The median tumor thickness was 6.0 mm; the median follow-up was 2.6 years. In multivariable analysis including nodal status and primary tumor ulceration, Ki-67 expression was an independent predictor of worse recurrence-free survival (HR 2.19, P = 0.024) and overall survival (HR 2.49, P = 0.028). Natural log-transformed tumor thickness (ln [thickness]) was also significantly associated with worse OS (HR 2.39, P = 0.010). We identify Ki-67 and ln (thickness) as potential biomarkers for patients with thick melanoma who have undergone nodal staging. If validated in additional studies, these biomarkers could be integrated into the staging criteria to improve risk-stratification.

The Prognostic Significance of Sentinel Lymph Node Status for Patients with Thick Melanoma.

Sentinel lymph node biopsy (SLNB) is recommended for patients with intermediate-thickness melanoma, but the use of SLNB for patients with thick melanoma is debated. This report presents a single-institution study investigating factors predictive of sentinel lymph node (SLN) metastasis and outcome for thick-melanoma patients . A retrospective review of a single-institution database from 1997 to 2012 identified 147 patients with thick primary cutaneous melanoma (≥4mm) who had an SLNB. Clinicopathologic characteristics were correlated with nodal status and outcome. The median age of the patients was 67years, and 61.9% of the patients were men. The median tumor thickness was 5.5mm, and 54 patients (36.7%) had a positive SLN. Multivariable analysis showed that only tumor thickness significantly predicted SLN metastasis (odds ratio 1.14; 95% confidence interval (CI) 1.02-1.28; P=0.02). The overall median follow-up period was 34.6months. Overall survival (OS) and melanoma-specific survival (MSS) were significantly worse for the positive versus negative-SLN patients. Multivariable analysis showed that age [hazard ratio (HR) 1.04; 95% CI 1.01-1.07; P=0.02] and SLN status (HR 2.24; 95% CI 1.03-4.88; P=0.04) significantly predicted OS, whereas only SLN status (HR 3.85; 95% CI 2.13-6.97; P<0.01) significantly predicted MSS. Tumor thickness predicts SLN status in thick melanomas. Furthermore, SLN status is prognostic for OS and MSS in thick-melanoma patients, with positive-SLN patients having significantly worse OS and MSS. These findings show that SLNB should be recommended for thick-melanoma patients, particularly because detection of SLN metastasis can identify patients for potential systemic therapy and treatment of nodal disease at a microscopic stage.

Abstract 2372: The genetic evolution of melanoma

Abstract The pathogenic mutations in melanoma have largely been catalogued, but the order of their occurrence is not known. We identified 82 cases of melanocytic neoplasia with two or more histopathologically distinct precursor and descendent portions. These portions spanned several histopathologic stages including benign nevi, intermediate neoplasms such as dysplastic nevi, melanoma in situ, invasive melanoma, and metastatic melanoma. In total, 277 histopathogically distinct areas were microdissected and sequenced using a panel of several hundred cancer-genes at an average of 275-fold coverage. In all cases precursor lesions harbored mutations known to activate the MAPK pathway, most commonly affecting BRAF or NRAS, and thus these were considered initiating mutations. TERT promoter mutations were the earliest secondary mutations to occur, emerging in intermediate neoplasms and in situ melanomas. Bi-allelic CDKN2A mutations and/or deletions arose predominantly at the transition to invasive melanoma. TP53 and PTEN mutations occurred comparatively later in thicker primary melanomas. In the 12 cases in which matched primaries and metastases were sequenced, no pathogenic mutations were specifically associated with the transition to metastatic melanoma, suggesting that metastatic capability was already present in the primary tumors. Unequivocally benign neoplasms, which mostly consisted of conventional nevi, disproportionately harbored BRAFV600E mutations as the only apparent pathogenic alteration. Lesions that were histopathologically intermediate, such as dysplastic nevi, had two or more pathogenic mutations and were enriched for NRAS mutations. These findings provide genetic support for the existence of an intermediate stage of melanocytic neoplasia, resolving a long-standing controversy. We also found that melanomas with different initiating mutations evolve through distinct evolutionary trajectories linked to specific histopathologic precursors. A mutational signature of UV-radiation-induced DNA damage predominated in lesions from all histopathologic stages, implicating UV-radiation in both the initiation and progression of melanoma. The point mutation burden increased steadily from one progression stage to the next, stabilizing once melanomas became invasive. By contrast, copy number alterations only became prevalent at the transition to invasive melanoma. Melanomas evolve from benign lesions linearly, whereas, they show patterns of branched evolution when they evolve from intermediate lesions; this indicates that evolution may accelerate once a melanocytic neoplasm reaches an intermediate stage. In summary, our study outlines a framework of the genetic evolution of melanocytic neoplasms from precursor lesions and unveils the rate-limiting homeostatic factors that become disrupted as neoplasms progress from one stage to the next, as well as the pathogenic factors driving this evolution. Citation Format: Alan H. Shain, Richard Yu, Iwei Yeh, Jamal Benhamida, Ivanka Kovalyshyn, Aravindhan Sriharan, Eric Talevich, Reinhard Dummer, Jeffrey North, Laura Pincus, Beth Ruben, William Rickaby, Corrado D’Arrigo, Alistair Robson, Robert Judson, Nancy Joseph, Boris Bastian. The genetic evolution of melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2372.

Prognostic value of mitoses in thick primary melanoma.

e21046Background: Patients with thick primary melanomas ( ≥ 4mm) have variable outcomes. With the availability of promising adjuvant therapies, new tools are needed to identify subsets of patients ...

Thin and thick primary cutaneous melanomas reveal distinct patterns of somatic copy number alterations.

Cutaneous melanoma is one of the most aggressive type of skin tumor. Early stage melanoma can be often cured by surgery; therefore current management guidelines dictate a different approach for thin (<1mm) versus thick (>4mm) melanomas. We have carried out whole-exome sequencing in 5 thin and 5 thick fresh-frozen primary cutaneous melanomas. Unsupervised hierarchical clustering analysis of somatic copy number alterations (SCNAs) identified two groups corresponding to thin and thick melanomas. The most striking difference between them was the much greater abundance of SCNAs in thick melanomas, whereas mutation frequency did not significantly change between the two groups. We found novel mutations and focal SCNAs in genes that are embryonic regulators of axon guidance, predominantly in thick melanomas. Analysis of publicly available microarray datasets provided further support for a potential role of Ephrin receptors in melanoma progression. In addition, we have identified a set of SCNAs, including amplification of BRAF and ofthe epigenetic modifier EZH2, that are specific for the group of thick melanomas that developed metastasis during the follow-up. Our data suggest that mutations occur early during melanoma development, whereas SCNAs might be involved in melanoma progression.

MicroRNA-10b is a prognostic biomarker for melanoma

Malignant melanoma is an aggressive form of skin cancer. Recently, drug therapy of advanced disease has been revolutionized by new agents. More therapeutic options, coupled with the desire to extend treatment to the adjuvant setting mean that prognostic biomarkers that can be assayed from formalin-fixed paraffin-embedded clinical would be valuable. microRNAs have potential to fill this need. We analyzed 377 microRNAs in 79 primary melanomas and 32 metastases using a split sample discovery strategy. From a discovery analysis using 40 thick primary melanomas (20 cases with metastasis and 20 controls without metastasis at 5 years), microRNA expression was measured by quantitative RT-PCR (QRT-PCR). MiR-10b emerged as a candidate prognostic microRNA. This was confirmed in an independent validation set of thick primary melanomas (20 cases with metastasis and 19 controls without metastasis at 5 years). In the combined discovery and validation cohorts (n=79), miR-10b expression showed a 3.7-fold increase in expression between cases and controls (P=0.005) and showed a trend of increasing expression between primary melanomas and their matched metastases (P<0.001). In situ hybridization showed expression was in melanoma cells and correlated with expression measured by QRT-PCR (P=0.0005). We used the combined discovery and validation samples to verify the prognostic value of additional candidate microRNAs identified from other studies, and proceeded to analyze miR-200b. We demonstrated that miR-10b and miR-200b showed independent prognostic value (P=0.002 and 0.047, respectively) in multivariable analysis alongside known clinico-pathological prognostic features (eg, Breslow thickness) using a Cox proportional hazards regression model. Furthermore, the addition of these microRNAs to the clinico-pathological features led to an improved regression model with better identification of aggressive thick melanomas. Taken together, these data suggest that miR-10b is a new prognostic microRNA for melanoma and that there could be a place for microRNA analysis in stratifying melanoma for therapy.