Technological advances for the detection of melanoma: Part II. Advances in molecular techniques
The growth of molecular technologies analyzing skin cells and inherited genetic variations has the potential to address current gaps in both diagnostic accuracy and prognostication in melanoma patients or in individuals at risk for developing melanoma. In part II of this continuing medical education article, novel molecular technologies are reviewed. These have been developed as adjunct tools for melanoma management and include the Pigmented Lesion Assay (PLA), myPath Melanoma, and DecisionDx-Melanoma tests, and genetic testing in patients with a strong familial melanoma history. These tests are commercially available and marketed as ancillary tools for clinical decision-making, diagnosis, and prognosis. Here we review fundamental principles behind each test, discuss peer-reviewed literature assessing their performance, and highlight the utility and limitations of each assay. The goal of this article is to provide a comprehensive, evidence-based foundation for clinicians regarding management of patients with difficult pigmented lesions.
Technological advances for the detection of melanoma: Advances in diagnostic techniques
Managing the balance between accurately identifying early stage melanomas while avoiding obtaining biopsy specimens of benign lesions (ie, overbiopsy) is the major challenge of melanoma detection. Decision making can be especially difficult in patients with extensive atypical nevi. Recognizing that the primary screening modality for melanoma is subjective examination, studies have shown a tendency toward overbiopsy. Even low-risk routine surgical procedures are associated with morbidity, mounting health care costs, and patient anxiety. Recent advancements in noninvasive diagnostic modalities have helped improve diagnostic accuracy, especially when managing melanocytic lesions of uncertain diagnosis. Breakthroughs in artificial intelligence have also shown exciting potential in changing the landscape of melanoma detection. In the first article in this continuing medical education series, we review novel diagnostic technologies, such as automated 2- and 3-dimensional total body imaging with sequential digital dermoscopic imaging, reflectance confocal microscopy, and electrical impedance spectroscopy, and we explore the logistics and implications of potentially integrating artificial intelligence into existing melanoma management paradigms.
MC1R variants and cutaneous melanoma risk according to histological type, body site, and Breslow thickness: a pooled analysis from the M-SKIP project
Little is known on whether melanocortin 1 receptor (MC1R) associated cutaneous melanoma (CM) risk varies depending on histological subtype and body site, and whether tumour thickness at diagnosis (the most important prognostic factor for CM patients) differs between MC1R variant carriers and wild-type individuals. We studied the association between MC1R variants and CM risk by histological subtype, body site, and Breslow thickness, using the database of the M-SKIP project. We pooled individual data from 15 case-control studies conducted during 2005-2015 in Europe and the USA. Study-specific, multi-adjusted odds ratios were pooled into summary odds ratios (SOR) and 95% confidence intervals (CI) using random-effects models. Six thousand eight hundred ninety-one CM cases and 5555 controls were included. CM risk was increased among MC1R variant carriers vs. wild-type individuals. The increase in risk was comparable across histological subtypes (SOR for any variant vs. wild-type ranged between 1.57 and 1.70, always statistical significant) except acral lentiginous melanoma (ALM), for which no association emerged; and slightly greater on chronically (1.74, 95% CI 1.47-2.07) than intermittently (1.55, 95% CI 1.34-1.78) sun-exposed skin. CM risk was greater for those carrying 'R' vs. 'r' variants; correlated with the number of variants; and was more evident among individuals not showing the red hair colour phenotype. Breslow thickness was not associated with MC1R status. MC1R variants were associated with an increased risk of CM of any histological subtype (except ALM) and occurring on both chronically and intermittently sun-exposed skin.
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Melanoma Prognosis - Accuracy of the American Joint Committee on Cancer Staging Manual Eighth Edition
BACKGROUND:The American Joint Committee on Cancer (AJCC) maintains that the eighth edition of its Staging Manual (AJCC8) has improved accuracy compared to the seventh (AJCC7). However, there are concerns that implementation may disrupt analysis of active clinical trials for stage III patients. We used an independent cohort of melanoma patients to test the extent to which AJCC8 has improved prognostic accuracy compared to AJCC7. METHODS:We analyzed a cohort of 1,315 prospectively enrolled patients. We assessed primary tumor and nodal classification of stage I-III patients using AJCC7 and AJCC8 to assign disease stages at diagnosis. We compared recurrence-free (RFS) and overall survival (OS) using Kaplan-Meier curves and log-rank tests. We then compared concordance indices of discriminatory prognostic ability and area under the curve (AUC) of 5-year survival to predict RFS/OS. All statistical tests were two-sided. RESULTS:Stage IIC continued to have worse outcomes than those for stage IIIA patients, with 5-year RFS of 26.5% (95%CI=12.8-55.1%) vs. 56.0% (95%CI=37.0-84.7%) by AJCC8 (Pâ€‰=â€‰0.002). For stage I, removing mitotic index as T classification factor decreased its prognostic value, although not statistically significantly (RFS C-index=0.63 [95%CI=0.56-0.69] to 0.56 [95%CI=0.49-0.63], Pâ€‰=â€‰0.07; OS C-index=0.48 [95%CI=0.38-0.58] to 0.48 [95%CI=0.41-0.56], Pâ€‰=â€‰0.90). For stage II, prognostication remained constant (RFS C-index=0.65 [95%CI=0.57-0.72]; OS C-index=0.61 [95%CI=0.50-0.72]), and. For stage III, AJCC8 yielded statistically significantly enhanced prognostication for RFS (C-index=0.65 [95%CI=0.60-0.70] to 0.70 [95%CI=0.66-0.75], Pâ€‰=â€‰0.01). CONCLUSIONS:Compared with AJCC7, we demonstrate that AJCC8 enables more accurate prognosis for patients with stage III melanoma. Restaging a large cohort of patients can enhance the analysis of active clinical trials.
Prognostic Gene Expression Profiling in Cutaneous Melanoma: Identifying the Knowledge Gaps and Assessing the Clinical Benefit
Importance/UNASSIGNED:Use of prognostic gene expression profile (GEP) testing in cutaneous melanoma (CM) is rising despite a lack of endorsement as standard of care. Objective/UNASSIGNED:To develop guidelines within the national Melanoma Prevention Working Group (MPWG) on integration of GEP testing into the management of patients with CM, including (1) review of published data using GEP tests, (2) definition of acceptable performance criteria, (3) current recommendations for use of GEP testing in clinical practice, and (4) considerations for future studies. Evidence Review/UNASSIGNED:The MPWG members and other international melanoma specialists participated in 2 online surveys and then convened a summit meeting. Published data and meeting abstracts from 2015 to 2019 were reviewed. Findings/UNASSIGNED:The MPWG members are optimistic about the future use of prognostic GEP testing to improve risk stratification and enhance clinical decision-making but acknowledge that current utility is limited by test performance in patients with stage I disease. Published studies of GEP testing have not evaluated results in the context of all relevant clinicopathologic factors or as predictors of regional nodal metastasis to replace sentinel lymph node biopsy (SLNB). The performance of GEP tests has generally been reported for small groups of patients representing particular tumor stages or in aggregate form, such that stage-specific performance cannot be ascertained, and without survival outcomes compared with data from the American Joint Committee on Cancer 8th edition melanoma staging system international database. There are significant challenges to performing clinical trials incorporating GEP testing with SLNB and adjuvant therapy. The MPWG members favor conducting retrospective studies that evaluate multiple GEP testing platforms on fully annotated archived samples before embarking on costly prospective studies and recommend avoiding routine use of GEP testing to direct patient management until prospective studies support their clinical utility. Conclusions and Relevance/UNASSIGNED:More evidence is needed to support using GEP testing to inform recommendations regarding SLNB, intensity of follow-up or imaging surveillance, and postoperative adjuvant therapy. The MPWG recommends further research to assess the validity and clinical applicability of existing and emerging GEP tests. Decisions on performing GEP testing and patient management based on these results should only be made in the context of discussion of testing limitations with the patient or within a multidisciplinary group.
TERT, BRAF, and NRAS mutational heterogeneity between paired primary and metastatic melanoma tumors
Mutational heterogeneity can contribute to therapeutic resistance in solid cancers. In melanoma, the frequency of inter- and intra-tumoral heterogeneity is controversial. We examined mutational heterogeneity within individual melanoma patients using multi-platform analysis of commonly mutated driver and non-passenger genes. We analyzed paired primary and metastatic tumors from 60 patients, and multiple metastatic tumors from 39 patients whose primary tumors were unavailable (n=271 tumors). We used a combination of multiplex SNaPshot assays, Sanger Sequencing, Mutation-specific PCR, or droplet digital PCR to determine the presence of BRAFV600, NRASQ61, and TERT-124C>T and TERT-146C>T mutations. Mutations were detected in BRAF (39%), NRAS (21%) and/or TERT (78%). Thirteen patients had TERTmutant discordant tumors; seven of these had a single tumor with both TERT-124C>T and TERT-146C>T mutations present at different allele frequencies. Two patients had both BRAF and NRAS mutations; one in different tumors and the other had a single tumor with both mutations. One patient with a BRAFmutant primary lacked mutant BRAF in least one of their metastases. Overall, we identified mutational heterogeneity in 18/99 (18%) patients. These results suggest that some primary melanomas may be comprised of subclones with differing mutational profiles. Such heterogeneity may be relevant to treatment responses and survival outcomes.
New Systematic Therapies and Trends in Cutaneous Melanoma Deaths Among US Whites, 1986-2016
Objectives. To determine the effect of new therapies and trends toward reduced mortality rates of melanoma.Methods. We reviewed melanoma incidence and mortality among Whites (the group most affected by melanoma) in 9 US Surveillance, Epidemiology, and End Results registry areas that recorded data between 1986 and 2016.Results. From 1986 to 2013, overall mortality rates increased by 7.5%. Beginning in 2011, the US Food and Drug Administration approved 10 new treatments for metastatic melanoma. From 2013 to 2016, overall mortality decreased by 17.9% (annual percent change [APC]â€‰=â€‰-6.2%; 95% confidence interval [CI]â€‰=â€‰-8.7%, -3.7%) with sharp declines among men aged 50 years or older (APCâ€‰=â€‰-8.3%; 95% CIâ€‰=â€‰-12.2%, -4.1%) starting in 2014. This recent, multiyear decline is the largest and most sustained improvement in melanoma mortality ever observed and is unprecedented in cancer medicine.Conclusions. The introduction of new therapies for metastatic melanoma was associated with a significant reduction in population-level mortality. Future research should focus on developing even more effective treatments, identifying biomarkers to select patients most likely to benefit, and renewing emphasis on public health approaches to reduce the number of patients with advanced disease. (Am J Public Health. Published online ahead of print March 19, 2020: e1-e3. doi:10.2105/AJPH.2020.305567).
Validation of Circulating Tumor DNA Assays for Detection of Metastatic Melanoma
The detection of cell-free, circulating tumor DNA (ctDNA) in the blood of patients with solid tumors is often referred to as "liquid biopsy." ctDNA is particularly attractive as a candidate biomarker in the blood. It is relatively stable after blood collection, can be easily purified, and can be quantitatively measured with high sensitivity and specificity using advanced technologies. Current liquid biopsy research has focused on detecting and quantifying ctDNA to (1) diagnose and characterize mutations in a patient's cancer to help select the appropriate treatment; (2) predict clinical outcomes associated with different treatments; and (3) monitor the response and/or progression of a patient's disease. The diagnostic use of liquid biopsies is probably greatest in tumors where the difficulty and/or risk of obtaining a tissue specimen for molecular diagnostics is high (e.g., lung, colon). In metastatic melanoma, however, obtaining a tissue sample for molecular diagnostics is not typically a major obstacle to patient care plans; rather predicting treatment outcomes and monitoring a patient's disease course during therapy are considered the current priorities for this cancer type. In this chapter we describe an approach to the validation of ctDNA detection assays for melanoma, focusing primarily on analytical validation, and provide methods to guide the use of droplet digital PCR assays for measuring ctDNA levels in plasma samples.
Circulating tumor DNA (ctDNA) kinetics and survival outcomes in patients (pts) with metastatic melanoma (MM) and brain metastases (BM) treated with dabrafenib (D)+ trametinib (T) in the COMBI-MB trial [Meeting Abstract]
Nearly 50% of pts with MM are diagnosed with BM. Although baseline ctDNA levels and changes during treatment predict clinical outcome after targeted and immunotherapy, no prospective trials have evaluated pre-and on-treatment ctDNA kinetics in pts with BM. We measured BRAF V600E ctDNA at baseline and in longitudinally collected plasma samples before progression for up to 40 weeks in 38 pts with intracranial (IC) and extracranial (EC) disease enrolled in cohort A (asymptomatic MM with BM; no previous local brain therapy; ECOG PS <=1) of the phase 2 COMBI-MB trial (NCT02039947) evaluating D+T in pts with MM and BM. ctDNA was quantified using a validated mutation-specific droplet digital PCR assay (threshold, 0.25 copies/mL). Separately, 20 of 21 samples from 9 pts with isolated IC disease had no detectable ctDNA; those pts were excluded. Progression-free survival (PFS), overall survival (OS), and IC and EC RECIST responses were analyzed. Baseline ctDNA was detectable in 34 of 38 pts (89%); ctDNA copy numbers were correlated with EC (Pearson r = 0.48; p = 0.0042) but not with IC (Pearson r = 0.16; p = 0.3257) disease volume. Presence/absence of baseline ctDNA was not correlated with IC or EC best overall response (BOR); baseline ctDNA levels were significantly associated with PFS (HR, 1.17 [95%CI, 1.05-1.30]; p = 0.0024) and OS (HR, 1.21 [95%CI, 1.07- 1.38]; p = 0.0020). ctDNA zeroconversion over time (including all longitudinal on-treatment samples) was significantly correlated with EC BOR (OR, 5.8; p = 0.04) but less so with IC BOR. Although these analyses confirm recent findings that ctDNA is not a good biomarker for monitoring CNS responses and associated clinical outcome, we found some associations between baseline ctDNA levels and PFS/OS as well as ctDNA zeroconversion and EC response