Clinical benefit of baseline imaging in Merkel cell carcinoma: Analysis of 584 patients

[Merkel cell carcinoma: An update]

Merkel cell carcinoma (MCC) is a rare skin cancer that mainly affects the elderly, and whose incidence is increasing. Although the exact origin of this cancer remains uncertain, research in recent years has revealed that MCC develops through two oncogenesis pathways: virally induced by the Merkel polyomavirus (80% of cases) and induced by mutations linked to ultraviolet rays (20% of cases). MCC is an aggressive cancer, with a high mortality rate and limited therapeutic options in advanced stage. In localized stages, the recommendations remain surgical excision, with almost systematic additional treatment by radiotherapy to reduce the risk of recurrence; there is currently no approved recommendation for adjuvant immunotherapy at this stage. In advanced stages, PD-1/PD-L1 inhibitors as monotherapy have considerably improved the prognosis of patients and are recommended as first-line therapy. However, more than 50 % of patients have primary or secondary failure of these treatments, with no satisfactory option available to date. The use of dual immunotherapy ipilimumab/nivolumab in these refractory patients, or new strategies such as adjuvant or neoadjuvant immunotherapy, are the strategies currently being explored. This article will review the current guidelines on the management of MCC with a summary of the most recent scientific advances.

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that is highly radiosensitive and immunogenic. Immunotherapy is the primary treatment of advanced disease, and immune checkpoint inhibitors show promise as neoadjuvant or adjuvant therapy in patients with high-risk resectable MCC. Emerging biomarkers of tumor burden are becoming increasingly important in identifying high-risk patients and in post-treatment surveillance. Further research is needed to determine the optimal duration of anti-PD-(L)1 treatment and second-line options for patients with MCC refractory to immunotherapy. This review covers the characteristics and management of MCC including recent innovations and areas of active investigation.

The prognostic value of the Merkel cell polyomavirus serum antibody test: A dual institutional observational study

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive cancer with often poor outcomes. Limited biomarkers exist for predicting clinical outcomes. The Merkel cell polyomavirus (MCPyV) serum antibody test (AMERK) has shown potential for indicating better recurrence-free survival in a single-institution study. The study aimed to evaluate the link between initial AMERK serostatus and survival. Secondary objectives included examining the relationship between initial AMERK titer levels and tumor burden.

METHODS

A retrospective cohort study across two institutions analyzed patients tested with AMERK within 90 days of MCC diagnosis. Regression models assessed the association of survival outcomes with serostatus, considering various factors. The relationship between AMERK titer and tumor burden indicators was evaluated using ANOVA. Significance testing was exploratory, without a fixed significance level.

RESULTS

Of 261 MCC patients tested, 49.4% were initially seropositive (titer ≥75). Multivariable analysis showed that seropositivity improved recurrence, event-free, overall, and MCC-specific survival rates. Strong associations were found between initial AMERK titer and clinical, tumor, and nodal stages, tumor size, and disease extent. Notably, improved survival with seropositivity was observed only in patients with localized disease at initial presentation.

CONCLUSION

Circulating antibodies to MCPyV oncoproteins, as indicated by the AMERK test, are linked with better survival in MCC patients with localized disease at presentation. This could enhance patient risk profiling and treatment personalization. The study's retrospective nature and exploratory analysis are key limitations.

PLAIN LANGUAGE SUMMARY

Merkel cell carcinoma (MCC) is a potentially aggressive skin cancer, and tools to predict patient outcomes are limited. A blood test called anti-Merkel cell panel (AMERK), which checks for specific antibodies related to this cancer, might give us some clues. In this study, we looked at 261 MCC patients who took the AMERK test within 90 days of diagnosis. We found that patients with an initial positive AMERK result tended to have better outcomes, especially if their cancer was in the early stages. However, it is important to note that this study has limitations, including using retrospective data and exploratory analyses.

Unmasking hidden Merkel cell carcinoma recurrences: Three illustrative cases of patients with rising viral oncoprotein antibody levels and challenge of requiring multi-modal imaging to detect clinical disease

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a high risk of recurrence and metastasis. Regular surveillance through physical exams and imaging studies is crucial for the timely detection of recurrences. MCC patients who produce antibodies to the Merkel cell polyomavirus oncoprotein may benefit from antibody testing in addition to routine imaging surveillance for the early detection of disease recurrence. The clinically available Anti MERKel cell panel (AMERK) is a sensitive tumor marker for Merkel cell polyomavirus positive MCC. Although AMERK is highly sensitive, imaging remains necessary to confirm the location of disease recurrence. MCC exhibits characteristic imaging features, making appropriate imaging modalities, and interpretation important for detection. We present 3 representative patient cases that highlight effective utilization of the AMERK test in addition to imaging for the early detection of MCC recurrence. The rise in the AMERK titer may occur before the disease reaches detectable size on computed tomography scans. Positron emission tomography (PET)-CT can serve as an alternative modality for the early detection of disease. Even subtle abnormalities in 18F-FDG uptake may be significant if accompanied by an increased AMERK titer. Alternative imaging modalities, such as 68Ga-DOTATATE PET-CT and magnetic resonance imaging, can be useful in revealing clinically occult disease in MCC patients. In summary, the AMERK antibody test, alongside imaging, enhances sensitivity in detecting recurrence. By combining these strategies of blood test and imaging, healthcare professionals can identify early signs of MCC recurrence, leading to prompt interventions and improved patient outcomes.

Merkel cell carcinoma: updates in tumor biology, emerging therapies, and preclinical models

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma thought to arise via either viral (Merkel cell polyomavirus) or ultraviolet-associated pathways. Surgery and radiotherapy have historically been mainstays of management, and immunotherapy has improved outcomes for advanced disease. However, there remains a lack of effective therapy for those patients who fail to respond to these established approaches, underscoring a critical need to better understand MCC biology for more effective prognosis and treatment. Here, we review the fundamental aspects of MCC biology and the recent advances which have had profound impact on management. The first genetically-engineered mouse models for MCC tumorigenesis provide opportunities to understand the potential MCC cell of origin and may prove useful for preclinical investigation of novel therapeutics. The MCC cell of origin debate has also been advanced by recent observations of MCC arising in association with a clonally related hair follicle tumor or squamous cell carcinoma in situ. These studies also suggested a role for epigenetics in the origin of MCC, highlighting a potential utility for this therapeutic avenue in MCC. These and other therapeutic targets form the basis for a wealth of ongoing clinical trials to improve MCC management. Here, we review these recent advances in the context of the existing literature and implications for future investigations.

Interdisciplinary management of skin cancer

The interdisciplinary treatment of skin cancer in the head and neck area requires close collaboration between different specialist disciplines. The most common non-melanoma skin cancer tumor entities are cutaneous squamous cell carcinoma and basal cell carcinoma as well as their precursor lesions. One of the less common tumors is Merkel cell carcinoma, which also occurs primarily in light-exposed areas and, in contrast to squamous and basal cell carcinoma, is more likely to metastasize. Due to the low tendency of basal cell carcinoma as well as cutaneous squamous cell carcinoma to metastasize, a cure can often be achieved by surgery. If the tumor growth exceeds certain levels it may require collaboration between dermatology and otorhinolaryngology. The primary goal of this interdisciplinary collaboration is to achieve a functional, cosmetically and aesthetically acceptable result in addition to adequate tumor treatment. Depending on the stage of the tumor and the clinical course, a case may be discussed in an interdisciplinary tumor board in order to determine a personalised, appropriate and adequate treatment concept for each patient, including prevention, therapy and follow-up.

Merkel-cell carcinoma: ESMO-EURACAN Clinical Practice Guideline for diagnosis, treatment and follow-up

•This ESMO Clinical Practice Guideline provides key recommendations for managing Merkel-cell carcinoma (MCC). •Recommendations are based on available scientific data and the multidisciplinary group of experts’ collective opinion. •The guideline covers clinical and pathological diagnosis, staging and risk assessment, treatment and follow-up. •Algorithms for the management of locoregional and inoperable/metastatic disease are provided. •A multidisciplinary team with a high level of expertise in MCC should diagnose and make decisions about therapy.

Moderne Diagnostik und Therapie des Merkelzellkarzinoms

Das Merkelzellkarzinom (MCC) ist ein seltener, aggressiver Hauttumor mit epithelialer und neuroendokriner Differenzierung, dessen Inzidenz in den letzten Jahrzehnten deutlich zugenommen hat. Risikofaktoren sind fortgeschrittenes Lebensalter, heller Hauttyp, UV‐Exposition und Immunsuppression. Pathogenetisch wird ein durch das Merkelzell‐Polyomavirus (MCPyV) hervorgerufener Typ von einem UV‐induzierten Typ mit hoher Tumormutationslast unterschieden.

Klinisch präsentiert sich das MCC als meist schmerzloser, schnell wachsender, rötlich‐violetter Tumor mit glänzender Oberfläche, der bevorzugt im Kopf‐Hals‐Bereich und an den distalen Extremitäten lokalisiert ist. Eine sichere Diagnose kann nur anhand histologischer und immunhistochemischer Merkmale gestellt werden. Bei Erstdiagnose weisen 20%–26% der Patienten lokoregionäre Metastasen und 8%–14% Fernmetastasen auf, weshalb eine Ausbreitungsdiagnostik unabdingbar ist. Bei fehlenden klinischen Hinweisen auf Metastasen wird eine Sentinel‐Lymphknotenbiopsie empfohlen.

Wesentliche Säulen der Therapie sind die Operation, die adjuvante oder palliative Strahlentherapie und in fortgeschrittenen inoperablen Stadien die medikamentöse Tumortherapie. Die Einführung von Immuncheckpoint‐Inhibitoren führte zu einem Paradigmenwechsel, da sich hiermit ein wesentlich langfristigeres Ansprechen und bessere Überlebensraten als mit Chemotherapie erreichen lassen. Zur Therapie des metastasierten MCC ist in Deutschland der PD‐L1‐Inhibitor Avelumab zugelassen, aber auch die PD‐1‐Antikörper Pembrolizumab und Nivolumab werden mit Erfolg eingesetzt. Adjuvante und neoadjuvante Therapiekonzepte, Immunkombinationstherapien und zielgerichtete Therapien als Monotherapie oder in Kombination mit Immuncheckpoint‐Inhibitoren befinden sich in klinischer Prüfung.

Modern diagnostics and treatment of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with epithelial and neuroendocrine differentiation, the incidence of which has increased substantially during the last decades. Risk factors include advanced age, fair skin type, UV exposure, and immunosuppression. Pathogenetically, a type caused by the Merkel cell polyomavirus is distinguished from a UV-induced type with a high tumor mutational burden. Clinically, MCC presents as a mostly painless, rapidly growing, reddish-violet tumor with a shiny surface, which is preferentially localized in the head-neck region and at the distal extremities. A reliable diagnosis can only be made based on histological and immunohistochemical features. At initial diagnosis, 20-26% of patients show locoregional metastases and 8-14% distant metastases, making staging examinations indispensable. If there is no clinical evidence of metastases, a sentinel lymph node biopsy is recommended. Essential columns of therapy are surgery, adjuvant or palliative radiotherapy and, in advanced inoperable stages, medicamentous tumor therapy. The introduction of immune checkpoint inhibitors has led to a paradigm shift, as they provide a considerably longer duration of response and better survival rates than chemotherapy. The PD-L1 inhibitor avelumab is approved for treatment of metastatic MCC in Germany, but the PD-1 antibodies pembrolizumab and nivolumab are also used with success. Adjuvant and neoadjuvant treatment concepts, immune combination therapies and targeted therapies as monotherapy or in combination with immune checkpoint inhibitors are in the clinical trial phase.

The Evolving Treatment Landscape of Merkel Cell Carcinoma

OPINION STATEMENT

Merkel cell carcinoma (MCC) has a high risk of recurrence and requires unique treatment relative to other skin cancers. The patient population is generally older, with comorbidities. Multidisciplinary and personalized care is therefore paramount, based on patient preferences regarding risks and benefits. Positron emission tomography and computed tomography (PET-CT) is the most sensitive staging modality and reveals clinically occult disease in ~ 16% of patients. Discovery of occult disease spread markedly alters management. Newly diagnosed, localized disease is often managed with sentinel lymph node biopsy (SLNB), local excision, primary wound closure, and post-operative radiation therapy (PORT). In contrast, metastatic disease is usually treated systemically with an immune checkpoint inhibitor (ICI). However, one or more of these approaches may not be indicated. Criteria for such exceptions and alternative approaches will be discussed. Because MCC recurs in 40% of patients and early detection/treatment of advanced disease is advantageous, close surveillance is recommended. Given that over 90% of initial recurrences arise within 3 years, surveillance frequency can be rapidly decreased after this high-risk period. Patient-specific assessment of risk is important because recurrence risk varies widely (15 to > 80%: Merkelcell.org/recur) depending on baseline patient characteristics and time since treatment. Blood-based surveillance tests are now available (Merkel cell polyomavirus (MCPyV) antibodies and circulating tumor DNA (ctDNA)) with excellent sensitivity that can spare patients from contrast dye, radioactivity, and travel to a cancer imaging facility. If recurrent disease is locoregional, management with surgery and/or RT is typically indicated. ICIs are now the first line for systemic/advanced MCC, with objective response rates (ORRs) exceeding 50%. Cytotoxic chemotherapy is sometimes used for debulking disease or in patients who cannot tolerate ICI. ICI-refractory disease is the major problem faced by this field. Fortunately, numerous promising therapies are on the horizon to address this clinical need.

Baseline ultrasound and FDG-PET/CT imaging in Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a cutaneous tumor with a high tendency to metastasize, and a significant proportion of patients have metastases at first presentation. This study aims to determine the value of baseline ultrasound (US) and ¹⁸ fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸ FDG-PET/CT) imaging in both patients with clinically localized MCC (Stage I/II) and patients who present with palpable lymph nodes (Stage III).

METHODS

This retrospective cohort included 135 MCC patients who underwent baseline US (with fine needle aspiration cytology (FNAC)) and/or FDG-PET/CT imaging between 2015 and 2021.

RESULTS

Of the 104 patients with clinically localized disease, 48% were upstaged to Stage III and 3% to Stage IV by imaging or sentinel lymph node biopsy (SLNB). FDG-PET/CT imaging identified regional metastases in 23%, while US with FNAC identified regional metastases in 19%. SLNB was performed in 56 patients, of whom 57% were upstaged to Stage III. Of the 31 patients who presented with palpable lymph nodes, 16% were upstaged to Stage IV by FDG-PET/CT imaging.

CONCLUSION

Baseline imaging frequently upstages Stage I/II MCC patients to Stage III, both by US and FDG-PET/CT, Stage IV disease is rarely identified. Patients who present with palpable nodes are frequently upstaged to Stage IV by FDG-PET/CT imaging.

An update on Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare cancer of the skin characterized by a neuroendocrine phenotype and an aggressive clinical behavior. It frequently originates in sun-exposed body areas, and its incidence has steadily increased in the last three decades. Merkel cell polyomavirus (MCPyV) and ultraviolet (UV) radiation exposure are the main causative agents of MCC, and distinct molecular features have been documented in virus-positive and virus-negative malignancies. Surgery remains the cornerstone of treatment for localized tumors, but even when integrated with adjuvant radiotherapy is able to definitively cure only a fraction of MCC patients. While characterized by a high objective response rate, chemotherapy is associated with a short-lasting benefit of approximately 3 months. On the other hand, immune checkpoint inhibitors including avelumab and pembrolizumab have demonstrated durable antitumor activity in patients with stage IV MCC, and investigations on their use in the neoadjuvant or adjuvant setting are currently underway. Addressing the needs of those patients who do not persistently benefit from immunotherapy is currently one of the most compelling unmet needs in the field, and multiple clinical trials of new tyrosine kinase inhibitors (TKIs), peptide receptor radionuclide therapy (PRRT), therapeutic vaccines, immunocytokines as well as innovative forms of adoptive cellular immunotherapies are under clinical scrutiny at present.

S2k Guideline - Merkel cell carcinoma (MCC, neuroendocrine carcinoma of the skin) - Update 2022

Merkel cell carcinoma (MCC, ICD-O M8247/3) is a rare, malignant, primary skin tumor with epithelial and neuroendocrine differentiation. The tumor cells share many morphologic, immunohistochemical, and ultrastructural features with cutaneous Merkel cells. Nevertheless, the cell of origin of MCC is unclear. MCC appears clinically as a reddish to purple spherical tumor with a smooth, shiny surface and a soft to turgid, elastic consistency, usually showing rapid growth. Spontaneous and often complete regressions of the tumor are observed. These likely immunologically-mediated regressions explain the cases in which only lymph node or distant metastases are found at the time of initial diagnosis and why the tumor responds very well to immunomodulatory therapies even at advanced stages. Due to its aggressiveness, the usually given indication for sentinel lymph node biopsy, the indication of adjuvant therapies to be evaluated, as well as the complexity of the necessary diagnostics, clinical management should already be determined by an interdisciplinary tumor board at the time of initial diagnosis.

Best practices in surgical and nonsurgical management of head and neck Merkel cell carcinoma: An update

Merkel cell carcinoma (MCC) is a rare, highly aggressive cutaneous neuroendocrine carcinoma. Controversy exists regarding optimal management of MCC as high-quality randomized studies and clinical trials are limited, and physicians are bound to interpret highly heterogeneous, retrospective literature in their clinical practice. Furthermore, the rising incidence and notably poor prognosis of MCC urges the establishment of best practices for optimal management of the primary tumor and its metastases. Herein, we summarized the relevant evidence and provided an algorithm for decision-making in MCC management based on the latest 2021 National Comprehensive Cancer Network guidelines. Additionally, we report current active MCC clinical trials in the United States. The initial management of MCC is dependent upon the pathology of the primary tumor and presence of metastatic disease. Patients with no clinical evidence of regional lymph node involvement generally require sentinel node biopsy (SLNB) while clinically node-positive patients should undergo fine needle aspiration (FNA) or core biopsy and full imaging workup. If SLNB or FNA/core biopsy are positive, a multidisciplinary team should be assembled to discuss if additional node dissection or adjuvant therapy is necessary. Wide local excision is optimal for primary tumor management and SLNB remains the preferred staging and predictive tool in MCC. The management of MCC has progressively improved in the last decade, particularly due to the establishment of immunotherapy as a new treatment option in advanced MCC. Ongoing trials and prospective studies are needed to further establish the best practices for MCC management.

Merkel Cell Carcinoma-Update on Diagnosis, Management and Future Perspectives

MCC is a rare but highly aggressive skin cancer. The identification of the driving role of Merkel cell polyomavirus (MCPyV) and ultraviolet-induced DNA damage in the oncogenesis of MCC allowed a better understanding of its biological behavior. The presence of MCPyV-specific T cells and lymphocytes exhibiting an 'exhausted' phenotype in the tumor microenvironment along with the high prevalence of immunosuppression among affected patients are strong indicators of the immunogenic properties of MCC. The use of immunotherapy has revolutionized the management of patients with advanced MCC with anti-PD-1/PD L1 blockade, providing objective responses in as much as 50-70% of cases when used in first-line treatment. However, acquired resistance or contraindication to immune checkpoint inhibitors can be an issue for a non-negligible number of patients and novel therapeutic strategies are warranted. This review will focus on current management guidelines for MCC and future therapeutic perspectives for advanced disease with an emphasis on molecular pathways, targeted therapies, and immune-based strategies. These new therapies alone or in combination with anti-PD-1/PD-L1 inhibitors could enhance immune responses against tumor cells and overcome acquired resistance to immunotherapy.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of nonmelanoma skin cancer

Nonmelanoma skin cancers (NMSCs) are some of the most commonly diagnosed malignancies. In general, early-stage NMSCs have favorable outcomes; however, a small subset of patients develop resistant, advanced, or metastatic disease, or aggressive subtypes that are more challenging to treat successfully. Recently, immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for the treatment of Merkel cell carcinoma (MCC), cutaneous squamous cell carcinoma (CSCC), and basal cell carcinoma (BCC). Although ICIs have demonstrated activity against NMSCs, the routine clinical use of these agents may be more challenging due to a number of factors including the lack of predictive biomarkers, the need to consider special patient populations, the management of toxicity, and the assessment of atypical responses. With the goal of improving patient care by providing expert guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew on the published literature as well as their own clinical experience to develop recommendations for healthcare professionals on important aspects of immunotherapeutic treatment for NMSCs, including staging, biomarker testing, patient selection, therapy selection, post-treatment response evaluation and surveillance, and patient quality of life (QOL) considerations, among others. The evidence- and consensus-based recommendations in this CPG are intended to provide guidance to cancer care professionals treating patients with NMSCs.

Nationwide multidisciplinary consensus on the clinical management of Merkel cell carcinoma: a Delphi panel

Merkel cell carcinoma (MCC) is a rare and highly aggressive cutaneous neuroendocrine carcinoma. The MCC incidence rate has rapidly grown over the last years, with Italy showing the highest increase among European countries. This malignancy has been the focus of active scientific research over the last years, focusing mainly on pathogenesis, new therapeutic trials and diagnosis. A national expert board developed 28 consensus statements that delineated the evolution of disease management and highlighted the paradigm shift towards the use of immunological strategies, which were then presented to a national MCC specialists panel for review. Sixty-five panelists answered both rounds of the questionnaire. The statements were divided into five areas: a high level of agreement was reached in the area of guidelines and multidisciplinary management, even if in real life the multidisciplinary team was not always represented by all the specialists. In the diagnostic pathway area, imaging played a crucial role in diagnosis and initial staging, planning for surgery or radiation therapy, assessment of treatment response and surveillance of recurrence and metastases. Concerning diagnosis, the usefulness of Merkel cell polyomavirus is recognized, but the agreement and consensus regarding the need for cytokeratin evaluation appears greater. Regarding the areas of clinical management and follow-up, patients with MCC require customized treatment. There was a wide dispersion of results and the suggestion to increase awareness about the adjuvant radiation therapy. The panelists unanimously agreed that the information concerning avelumab provided by the JAVELIN Merkel 200 study is adequate and reliable and that the expanded access program data could have concrete clinical implications. An immunocompromised patient with advanced MCC can be treated with immunotherapy after multidisciplinary risk/benefit assessment, as evidenced by real-world analysis and highlighted in the guidelines. A very high consensus regarding the addition of radiotherapy to treat the ongoing focal progression of immunotherapy was observed. This paper emphasizes the importance of collaboration and communication among the interprofessional team members and encourages managing patients with MCC within dedicated multidisciplinary teams. New insights in the treatment of this challenging cancer needs the contribution of many and different experts.

Merkel cell carcinoma in the hand. Report of two cases

Merkel-cell-carcinoma of the hand is rare. The Pathological and Immunohistochemical diagnosis helps us to focus the treatment. Immunotherapy has shown beneficial effects in unresectable/advanced/metastatic stages. The quantification of antibodies against Merkel-cell-polyomavirus (MCPyV) can be a useful for prognosis and follow-up. A wide margin in surgery and the sentinel node are the first option with Radiotherapy.

Scientific and clinical developments in Merkel cell carcinoma: A polyomavirus-driven, often-lethal skin cancer

Merkel cell carcinoma (MCC) is a primary neuroendocrine skin cancer that recurs in ~40% of cases. Merkel cell polyomavirus (MCPyV) and ultraviolet (UV)-induced mutations are two major causative factors of MCC. Virus-positive MCCs express polyomavirus oncoproteins that are highly immunogenic yet are required for ongoing tumor growth. Virus-negative MCCs have a high burden of UV-DNA mutations that encode tumor-specific UV-neoantigens. Thus, both UV- and virus-induced MCCs are highly immunogenic, enabling diverse T-cell targeted therapies. Optimal MCC management is challenging given its rarity, aggressive nature, rapidly evolving care guidelines, and fundamental differences in management compared to other skin cancers. MCC is often managed aggressively with extensive surgery, radiotherapy or systemic therapy, frequently leading to toxicities that might have been avoidable while still achieving optimal disease control. Thus, multi-disciplinary care is crucial for providing patients with the best possible outcomes. The outlook for many patients with advanced MCC has progressed remarkably over the past decade due to PD-1 pathway blocking agents that provide durable benefit for a substantial subset of MCC patients. The management of early-stage MCC has also improved due to better approaches to integrate surgery and radiotherapy. Prognostic accuracy and ongoing surveillance have advanced due to stage-specific recurrence data and sophisticated "liquid biopsies" that allow early detection of disease recurrence. Here we summarize both recent striking progress and pressing challenges such as PD-(L)1-refractory MCC, and management of MCC patients with immune dysfunction. We also highlight diverse resources to allow providers to take advantage of recent progress in this fast-moving field.

Merkel Cell Carcinoma of the Head and Neck: Epidemiology, Pathogenesis, Current State of Treatment and Future Directions

Merkel cell carcinoma (MCC) is a rare, cutaneous neuroendocrine malignancy with increasing incidence. The skin of the head and neck is a common subsite for MCC with distinctions in management from other anatomic areas. Given the rapid pace of developments regarding MCC pathogenesis (Merkel cell polyoma virus (MCPyV)-positive or virus-negative, cell of origin), diagnosis, staging and treatment, and up to date recommendations are critical for optimizing outcomes. This review aims to summarize currently available literature for MCC of the head and neck. The authors reviewed current literature, including international guidelines regarding MCC pathogenesis, epidemiology, diagnosis, staging, and treatment. Subsequently recommendations were derived including the importance of baseline imaging, MCPyV serology testing, primary site surgery, nodal evaluation, radiotherapy, and the increasing role of immune modulating agents in MCC. MCPyV serology testing is increasingly important with potential distinctions in treatment response and surveillance between virus-positive and virus-negative MCC. Surgical management continues to balance optimizing local control with minimal morbidity. Similarly, radiotherapy continues to have importance in the adjuvant, definitive, and palliative setting for MCC of the head and neck. Immunotherapy has changed the paradigm for advanced MCC, with increasing work focusing on optimizing outcomes for non-responders and high-risk patients, including those with immunosuppression.

A machine-learning modified CART algorithm informs Merkel cell carcinoma prognosis

BACKGROUND

Merkel cell carcinoma (MCC) is a rare neuroendocrine skin cancer with a high mortality rate. MCC staging is currently based on tumour primary size, clinical detectability of lymph node metastases, performance of a lymph node biopsy, and presence of distant metastases.

OBJECTIVE

We aimed to use a modified classification and regression tree (CART) algorithm using available data points in the National Cancer Database (NCDB) to elucidate novel prognostic factors for MCC.

METHODS

Retrospective cohort study of the NCDB and Surveillance, Epidemiology, and End Results (SEER) registries. Cases from the NCDB were randomly assigned to either the training or validation cohorts. A modified CART algorithm was created with data from the training cohort and used to identify prognostic groups that were validated in the NCDB validation and SEER cohorts.

RESULTS

A modified CART algorithm using tumour variables available in the NCDB identified prognostic strata as follows: I: local disease, II: ≤3 positive nodes, III: ≥4 positive nodes, and IV: presence of distant metastases. Three-year survival for these groups in the NCDB validation cohort were 81.2% (SE: 1.7), 59.6% (SE: 3.0), 38.0% (SE: 6.0), and 20.2% (SE: 7.0), respectively. These strata were exhibited greater within-group homogeneity than AJCC groups and were more predictive of survival.

CONCLUSIONS

Risk-stratified grouping of MCC patients incorporating positive lymph node count were strongly predictive of survival and demonstrated a high degree of within-group homogeneity and survival prediction. Incorporation of positive lymph node count within overall staging or sub-staging may help to improve future MCC staging criteria.

Merkel Cell Carcinoma: New Trends

Simple Summary

In this review, we discuss a rare skin cancer that occurs mostly in elderly people called “Merkel cell carcinoma” (MCC). The incidence is increasing due to ageing of the population, increased sun exposure, and the use of medication that inhibits the immune system. Unlike most other skin cancers, MCC grows rapidly and forms metastases easily. We discuss the biology and treatment of MCC. Management should be by an experienced and multidisciplinary team, and treatment must start quickly. The standard practice of MCC treatment is surgery followed by radiotherapy. However, because it concerns an elderly and often frail population, (extensive) surgery may not always be feasible due to the associated morbidity. In those situations, radiotherapy alone is a good alternative. An important new development is immunotherapy that can cause long-lasting responses in a significant proportion of the patients with recurrent or metastatic MCC.

Abstract

Merkel cell carcinoma (MCC) is a rare neuroendocrine tumor of the skin mainly seen in the elderly. Its incidence is rising due to ageing of the population, increased sun exposure, and the use of immunosuppressive medication. Additionally, with the availability of specific immunohistochemical markers, MCC is easier to recognize. Typically, these tumors are rapidly progressive and behave aggressively, emphasizing the need for early detection and prompt diagnostic work-up and start of treatment. In this review, the tumor biology and immunology, current diagnostic and treatment modalities, as well as new and combined therapies for MCC, are discussed. MCC is a very immunogenic tumor which offers good prospects for immunotherapy. Given its rarity, the aggressiveness, and the frail patient population it concerns, MCC should be managed in close collaboration with an experienced multidisciplinary team.

How we treat Merkel cell carcinoma: within and beyond current guidelines

Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with a high risk of local recurrence and distant metastasis. Optimal care of this potentially life-threatening cancer is critical but challenging because: physicians are often unfamiliar with its management due to rarity, and MCC management remains controversial, in part because it is rapidly evolving across multiple specialties. While guidelines offer a broad overview of management, they are often not sufficient when making decisions for individual patients. Herein, we present a literature review as well as practical approaches adopted at our institutions for staging, surveillance and therapy of MCC. Each of these areas are discussed in light of how they can be appropriately customized for prevalent but challenging situations. We also provide representative examples of MCC patient scenarios and how they were managed by a multidisciplinary team to identify suitable evidence-based, individualized treatment plans.

Merkel cell carcinoma (MCC) is a skin cancer with a high risk of recurrence and distant spread. Optimal care of this cancer is important. However, management is challenging because it is rare and its treatment is continuously evolving across multiple specialties. While treatment guidelines offer a broad overview of management, they are often not detailed enough to provide appropriate patient-specific assistance. Herein, we present a review of recent studies and our suggestions relevant to MCC staging, surveillance and treatment options. Each of these areas are discussed in light of how they can be appropriately customized for challenging situations often encountered by practitioners. We also provide representative examples of MCC patient scenarios and how they were managed by a multidisciplinary team to identify evidence-based, individualized treatment plans.

Positron Emission Tomography in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare neuroendocrine skin malignancy usually arising as a nonspecific nodule on sun-exposed areas of the head and neck. Given the poor prognosis of this aggressive tumor, assessment of disease burden in pre- and post-treatment care may ensure an optimal management with significant implications for patient surveillance and prognosis. Although imaging has established its role in locally advanced or distant metastatic MCC, a standard imaging algorithm is yet to be determined and respective recommendations are mainly based on melanoma. Positron emission tomography/computed tomography (PET/CT) is increasingly evolving as a valuable imaging tool in metastatic or unresectable MCC, mostly utilizing the glucose analogue 18F-fluorodeoxyglucose (18F-FDG) as a radiotracer. Despite being inferior in detecting the disease in its early stages compared to the "gold standard" of sentinel lymph node biopsy, recent evidence suggests an important role for 18F-FDG PET/CT in the routine workup of localized MCC. Moreover, 68Ga-labeled somatostatin analogues have been employed as PET tracers in the field of MCC with promising, yet comparable to 18F-FDG, results. This article provides a structured literature review of the most important studies investigating the role of PET or PET/CT in the clinical practice of MCC.