Incidence and survival for Merkel cell carcinoma in Queensland, Australia, 1993-2010

The Role of Neoadjuvant Immunotherapy in the Management of Merkel Cell Carcinoma with Clinically Detected Regional Lymph Node Metastasis

BACKGROUND

Immunotherapy is emerging as a promising option for certain locally advanced and metastatic cutaneous malignancies. However, the role of neoadjuvant immunotherapy (NIO) in Merkel cell carcinoma (MCC) with clinically detected regional lymph node metastasis (CDRLNM) has not been fully elucidated.

METHODS

For this study, MCC patients with CDRLNM who underwent surgical excision were selected from the National Cancer Database (NCDB). Those who received NIO were propensity-matched with those who did not, and Kaplan-Meier analysis was used to compare overall survival (OS).

RESULTS

Of the 1809 selected patients, 356 (19.7%) received NIO followed by wide excision (n = 352, 98.9%) or amputation (n = 4, 1.1%). The rate of complete pathologic response for the primary tumor (ypT0) was 45.2%. Only 223 patents (63.4%) also underwent lymph node dissection (LND). The complete pathologic nodal response (ypN0) rate for these patients was 17.9%. A pathologic complete response of both the primary tumor and the nodal basin (ypT0 ypN0) was seen in 16 of the 223 patients who underwent both primary tumor surgery and LND. Subsequently, 151 pairs were matched between the NIO and no-NIO groups (including only patients with LND). Kaplan-Meier analysis demonstrated a significant OS improvement with NIO (median not reached vs. 35.0 ± 8.0 months; p = 0.025). The 5-year OS was 57% in the NIO group versus 44% in no-NIO group (p = 0.021).

CONCLUSION

The study suggests that NIO in MCC with CDRLNM provides improved OS in addition to promising rates of primary complete response, which could change the profile of surgical resection. This supports ongoing clinical trials exploring the use of NIO in MCC.

Incidence, mortality and survival of Merkel cell carcinoma: a systematic review of population-based studies

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer that most commonly occurs in ultraviolet-exposed body sites. The epidemiology of MCC in different geographies and populations is not well characterized.

OBJECTIVES

The objective of this systematic review is to summarize evidence on the incidence, mortality and survival rates of MCC from population-based studies.

METHODS

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from database inception to 6 June 2023. No geographic, age or date exclusions were applied. We included population-based studies of MCC that reported the incidence, survival or mortality rate, and also considered systematic reviews. A data-charting form was created and validated to identify variables to extract. Two reviewers then independently charted the data for each included study with patient characteristics, and estimates of incidence rate, mortality rate, and survival rate and assessed the quality of included studies using the Joanna Briggs Institute Checklist for Prevalence studies, Newcastle-Ottawa Scale and Assessment of Multiple Systematic Reviews. We abstracted age-, sex-, stage- and race-stratified outcomes, and synthesized comparisons between strata narratively and using vote counting. We assessed the certainty of evidence for those comparisons using the Grading of Recommendations, Assessments, Developments and Evaluations framework.

RESULTS

We identified 11 472 citations, of which 52 studies from 24 countries met our inclusion criteria. Stage I and the head and neck were the most frequently reported stage and location at diagnosis. The incidence of MCC is increasing over time (high certainty), with the highest reported incidences reported in southern hemisphere countries [Australia (2.5 per 100 000); New Zealand (0.96 per 100 000) (high certainty)]. Male patients generally had higher incidence rates compared with female patients (high certainty), although there were some variations over time periods. Survival rates varied, with lower survival and/or higher mortality associated with male sex (moderate certainty), higher stage at diagnosis (moderate-to-high certainty), older age (moderate certainty), and immunosuppression (low-to-moderate certainty).

CONCLUSIONS

MCC is increasing in incidence and may increase further given the ageing population of many countries. The prognosis of MCC is poor, particularly for male patients, those who are immunosuppressed, and patients diagnosed at higher stages or at an older age.

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.

Merkel Cell Carcinoma: Integrating Epidemiology, Immunology, and Therapeutic Updates

Merkel cell carcinoma (MCC) is a rare skin cancer characterized by neuroendocrine differentiation. Its carcinogenesis is based either on the integration of the Merkel cell polyomavirus or on ultraviolet (UV) mutagenesis, both of which lead to high immunogenicity either through the expression of viral proteins or neoantigens. Despite this immunogenicity resulting from viral or UV-associated carcinogenesis, it exhibits highly aggressive behavior. However, owing to the rarity of MCC and the lack of epidemiologic registries with detailed clinical data, there is some uncertainty regarding the spontaneous course of the disease. Historically, advanced MCC patients were treated with conventional cytotoxic chemotherapy yielding a median response duration of only 3 months. Starting in 2017, four programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) immune checkpoint inhibitors-avelumab, pembrolizumab, nivolumab (utilized in both neoadjuvant and adjuvant settings), and retifanlimab-have demonstrated efficacy in treating patients with disseminated MCC on the basis of prospective clinical trials. However, generating clinical evidence for rare cancers, such as MCC, is challenging owing to difficulties in conducting large-scale trials, resulting in small sample sizes and therefore lacking statistical power. Thus, to comprehensively understand the available clinical evidence on various immunotherapy approaches for MCC, we also delve into the epidemiology and immune biology of this cancer. Nevertheless, while randomized studies directly comparing immune checkpoint inhibitors and chemotherapy in MCC are lacking, immunotherapy shows response rates comparable to those previously reported with chemotherapy but with more enduring responses. Notably, adjuvant nivolumab has proven superiority to the standard-of-care therapy (observation) in the adjuvant setting.

Metastatic merkel cell carcinoma to the thyroid gland: Case report and review of the literature

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive and rare neuroendocrine tumor, accounting for less than 1% of skin cancers. Metastasis primarily manifests in the cervical lymph nodes but rarely affect the thyroid.

METHODS

We report a case of primary head and neck cutaneous MCC with metastasis to the thyroid gland. A review of the literature of MCC with thyroid metastasis was conducted.

RESULTS

We identified five cases of MCC with thyroid metastasis. Primary sites included the distal upper and lower extremities, axilla, buttock, and groin. Treatment courses varied including thyroidectomy, immunotherapy, and expectant palliative measures. Time from initial diagnosis to thyroid metastasis ranged from four months to four years. Tissue diagnosis was achieved in 5 of 6 cases.

CONCLUSIONS

MCC with thyroid metastasis is rare and likely represents aggressive disease. Despite advances in treatment and surveillance, outcomes for MCC remain poor. Ongoing research may establish predictors for treatment response.

Merkel cell carcinoma recurrence risk estimation is improved by integrating factors beyond cancer stage: A multivariable model and web-based calculator

BACKGROUND

Merkel cell carcinoma (MCC) recurs in 40% of patients. In addition to stage, factors known to affect recurrence risk include: sex, immunosuppression, unknown primary status, age, site of primary tumor, and time since diagnosis.

PURPOSE

Create a multivariable model and web-based calculator to predict MCC recurrence risk more accurately than stage alone.

METHODS

Data from 618 patients in a prospective cohort were used in a competing risk regression model to estimate recurrence risk using stage and other factors.

RESULTS

In this multivariable model, the most impactful recurrence risk factors were: American Joint Committee on Cancer stage (P < .001), immunosuppression (hazard ratio 2.05; P < .001), male sex (1.59; P = .003) and unknown primary (0.65; P = .064). Compared to stage alone, the model improved prognostic accuracy (concordance index for 2-year risk, 0.66 vs 0.70; P < .001), and modified estimated recurrence risk by up to 4-fold (18% for low-risk stage IIIA vs 78% for high-risk IIIA over 5 years).

LIMITATIONS

Lack of an external data set for model validation.

CONCLUSION/RELEVANCE

As demonstrated by this multivariable model, accurate recurrence risk prediction requires integration of factors beyond stage. An online calculator based on this model (at merkelcell.org/recur) integrates time since diagnosis and provides new data for optimizing surveillance for MCC patients.

High-volume facilities are significantly more likely to use guideline-adherent systemic immunotherapy for metastatic Merkel cell carcinoma: implications for cancer care regionalization

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a high rate of mortality. While still relatively rare, the incidence of MCC has been rapidly rising in the US and around the world. Since 2017, two immunotherapeutic drugs, avelumab and pembrolizumab, have been FDA-approved for the treatment of metastatic MCC and have revolutionized outcomes for MCC. However, real-world outcomes can differ from clinical trial data, and the adoption of novel therapeutics can be gradual. We aimed to characterize the treatment practices and outcomes of patients with metastatic MCC across the US. A retrospective cohort study of adult cases of MCC in the National Cancer Database diagnosed from 2004 to 2019 was performed. Multivariable logistic regressions to determine the association of a variety of patient, tumor, and system factors with likelihood of receipt of systemic therapies were performed. Univariate Kaplan-Meier and multivariable Cox survival regressions were performed. We identified 1017 cases of metastatic MCC. From 2017 to 2019, 54.2% of patients received immunotherapy. This increased from 45.1% in 2017 to 63.0% in 2019. High-volume centers were significantly more likely to use immunotherapy (odds ratio 3.235, p = 0.002). On univariate analysis, patients receiving systemic immunotherapy had significantly improved overall survival (p < 0.001). One-, 3-, and 5-year survival was 47.2% (standard error [SE] 1.8%), 21.8% (SE 1.5%), and 16.5% (SE 1.4%), respectively, for patients who did not receive immunotherapy versus 62.7% (SE 3.5%), 34.4% (SE 3.9%), and 23.6% (SE 4.4%), respectively, for those who did (Fig. 1). In our multivariable survival regression, receipt of immunotherapy was associated with an approximately 35% reduction in hazard of death (hazard ratio 0.665, p < 0.001; 95% CI 0.548-0.808). Our results demonstrate that the real-world survival advantage of immunotherapy for metastatic MCC is similar to clinical trial data. However, many patients with metastatic disease did not receive this guideline-recommended therapy in our most recent study year, and use of immunotherapy is higher at high-volume centers. This suggests that regionalization of care to high-volume centers or dissemination of their practices, may ultimately improve patient survival.

Color Analysis of Merkel Cell Carcinoma: A Comparative Study with Cherry Angiomas, Hemangiomas, Basal Cell Carcinomas, and Squamous Cell Carcinomas

Merkel cell carcinoma (MCC) is recognized as one of the most malignant skin tumors. Its rarity might explain the limited exploration of digital color studies in this area. The objective of this study was to delineate color alterations in MCCs compared to benign lesions resembling MCC, such as cherry angiomas and hemangiomas, along with other non-melanoma skin cancer lesions like basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), utilizing computer-aided digital color analysis. This was a retrospective study where clinical images of the color of the lesion and adjacent normal skin from 11 patients with primary MCC, 11 patients with cherry angiomas, 12 patients with hemangiomas, and 12 patients with BCC/SCC (totaling 46 patients) were analyzed using the RGB (red, green, and blue) and the CIE Lab color system. The Lab color system aided in estimating the Individual Typology Angle (ITA) change in the skin, and these results are documented in this study. It was demonstrated that the estimation of color components can assist in the differential diagnosis of these types of lesions because there were significant differences in color parameters between MCC and other categories of skin lesions such as hemangiomas, common skin carcinomas, and cherry hemangiomas. Significant differences in values were observed in the blue color of RGB (p = 0.003) and the b* parameter of Lab color (p < 0.0001) of MCC versus cherry angiomas. Similarly, the mean a* value of Merkel cell carcinoma (MCC) compared to basal cell carcinoma and squamous cell carcinoma showed a statistically significant difference (p < 0.0001). Larger prospective studies are warranted to further validate the clinical application of these findings.

The prognostic role of PD-L1 expression and the presence of polyomavirus in Merkel cell carcinoma cases

BACKGROUND

Merkel cell carcinoma (MCC) comprises a rare malignant primary skin tumor presenting neuroendocrine differentiation. Recently, agents blocking the programmed cell death protein 1 and programmed cell death protein ligand 1 pathway (PD-1/PD-L1) have demonstrated objective and durable tumor regressions in patients presenting advanced MCC. This study aimed to describe the sociodemographic, clinical, and histopathological characteristics of MCC patients, also assessing the prevalence of PD-L1 expression and Merkel cell Polyomavirus (MCPyV), as well as their prognostic roles.

METHODS

Data from patients diagnosed with MCC between 1996 and 2019 at a reference cancer center in Rio de Janeiro, southeastern Brazil, were evaluated in a retrospective study. Tumor samples were tested for MCPyV and PD-L1 employing immunohistochemistry. Survival analyses were carried out employing the Kaplan-Meier method and curves were compared using the log-rank test. A multiple semiparametric Cox model was used. Values p < 0.05 were considered significant.

RESULTS

A total of 65 patients were included in the study, with a mean age at diagnosis of 72 (standard deviation 13.9). A total of 56.9% (37/65) of the patients were male, 86.2% (56/65) were white, and 56.9% (37/64) were illiterate or with incomplete elementary school. MCPyV immunohistochemistry was positive in 29 cases (44.6%) and PD-L1 positivity was ≥ 1% in 42 cases (64.6%). Significant associations between MCPyV and PD-L1 expression ≥ 1% (p = 0.003) and PD-L1 expression ≥ 5% (p = 0.005) were noted. Concerning the multivariate analysis, only education level and advanced MCC stage indicated statistically significant worse progression-free survival. Regarding overall survival (OS), being male, education level and advanced stage comprised risk factors. The estimated OS at 60 months for stages I to III was of 48.9% and for stage IV, 8.9%.

CONCLUSIONS

This is the first large Brazilian cohort to assess the prevalence of MCPyV in MCC tumors, as well as PD-L1 expression and their associations. No correlations were noted between MCPyV infection or PD-L1 expression and survival rates.

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.

Avelumab for Advanced Merkel Cell Carcinoma: Global Real-World Data on Patient Response and Survival

Introduction

Avelumab is a programmed cell death-ligand 1 (PD-L1) inhibitor approved by the Food and Drug Administration for advanced Merkel cell carcinoma (MCC). Studies conducted in real-world settings have shed light on its effectiveness and safety in clinical settings.

Areas Covered

Real-world studies on avelumab for MCC from North and South America, Europe, and Asia have been presented in this review. Most studies are on patients over age 70 and have a male-predominant sex ratio. Overall response rates range from 29.1% to 72.1%, (disease control rate: 60.0-72.7%; complete response rate: 15.8%-37.2%; partial rate: 18.2-42.1%; stable disease: 7.1-30.9%; progressive disease: 7.1-40.0%) and median progression free survival ranges from 8.1 to 24.1 months depending on the population studied. Immunosuppressed patients appear to benefit from avelumab as well, with response rates equivalent to the general population. Patients receiving avelumab as a first-line agent tend to have better outcomes than those using it as a second-line therapy. Fatigue, infusion-related reactions, and dyspnea were some of the most common adverse events identified in real-world studies. Autoimmune hepatitis and thyroiditis were also observed.

Conclusion

The use of avelumab as a safe and effective treatment option for advanced MCC is supported by real-world data, although additional study is required to assess long-term efficacy and safety outcomes.

The potential role of RNA modification in skin diseases, as well as the recent advances in its detection methods and therapeutic agents

RNA modification is considered as an epigenetic modification that plays an indispensable role in biological processes such as gene expression and genome editing without altering nucleotide sequence, but the molecular mechanism of RNA modification has not been discussed systematically in the development of skin diseases. This article mainly presents the whole picture of theoretical achievements on the potential role of RNA modification in dermatology. Furthermore, this article summarizes the latest advances in clinical practice related with RNA modification, including its detection methods and drug development. Based on this comprehensive review, we aim to illustrate the current blind spots and future directions of RNA modification, which may provide new insights for researchers in this field.

Critical involvement of circular RNAs in virus-associated cancers

Virus-related cancer is cancer where viral infection leads to the malignant transformation of the host's infected cells. Seven viruses (e.g., human papillomavirus (HPV), Epstein-Barr virus (EBV), Kaposi's sarcoma herpesvirus (KSHV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Human T-lymphotropic virus (HTLV), and Merkel cell polyomavirus (MCV)) that infect humans have been identified as an oncogene and have been associated with several human malignancies. Recently, growing attention has been attracted to exploring the pathogenesis of virus-related cancers. One of the most mysterious molecules involved in carcinogenesis and progression of virus-related cancers is circular RNAs (circRNA). These emerging non-coding RNAs (ncRNAs), due to the absence of 5' and 3' ends, have high stability than linear RNAs and are found in some species across the eukaryotic organisms. Compelling evidence has revealed that viruses also encode a repertoire of circRNAs, as well as dysregulation of these viral circRNAs play a critical role in the pathogenesis and progression of different types of virus-related cancers. Therefore, understanding the exact role and function of the virally encoded circRNAs with virus-associated cancers will open a new road for increasing our knowledge about the RNA world. Hence, in this review, we will focus on emerging roles of virus-encoded circRNAs in multiple cancers, including cervical cancer, gastric cancer, Merkel cell carcinoma, nasopharyngeal carcinoma, Kaposi cancer, and liver cancer.

Overall Survival After Mohs Surgery for Early-Stage Merkel Cell Carcinoma

Importance

Merkel cell carcinoma (MCC) is a rare cutaneous malignant neoplasm with increasing incidence and high mortality. Although it is accepted that the optimal treatment for localized tumors is surgical, the data surrounding the optimal surgical approach are mixed, and current National Comprehensive Cancer Network guidelines state that Mohs micrographic surgery (MMS) and wide local excision (WLE) can both be used. The current National Comprehensive Cancer Network guidelines do not advocate a preference for MMS or WLE and suggest that they can be used interchangeably.

Objective

To evaluate the association of surgical approach with overall survival after excision of localized T1/T2 MCC.

Design, Setting, and Participants

This retrospective cohort study used the National Cancer Database to assess adults with T1/T2 MCC who were diagnosed between January 1, 2004, and December 31, 2018, with pathologically confirmed, negative regional lymph nodes and treated with surgery. The National Cancer Database includes all reportable cases from Commission on Cancer-accredited facilities. Data analysis was performed from October 2022 to May 2023.

Exposure

Surgical approach.

Main Outcomes and Measures

Overall survival.

Results

A total of 2313 patients (mean [SD] age, 71 [10.6] years; 1340 [57.9%] male) were included in the study. Excision with MMS had the best unadjusted survival, with mean (SE) survival rates of 87.4% (3.4%) at 3 years, 84.5% (3.9%) at 5 years, and 81.8% (4.6%) at 10 years vs 86.1% (0.9%) at 3 years, 76.9% (1.2%) at 5 years, and 60.9% (2.0%) at 10 years for patients treated with WLE. Patients treated with narrow-margin excision had similar survival as those treated with WLE, with mean (SE) survival rates of 84.8% (1.4%) at 3 years, 78.3% (1.7%) at 5 years, and 60.8% (3.6%) at 10 years. On multivariable survival analysis, excision with MMS was associated with significantly improved survival compared with WLE (hazard ratio, 0.59; 95% CI, 0.36-0.97; P = .04). High-volume MCC centers were significantly more likely to use MMS over WLE compared with other centers (odds ratio, 1.99; 95% CI, 1.63-2.44; P < .001).

Conclusions and Relevance

In this cohort study, the use of MMS (compared with WLE) was associated with significantly improved survival for patients with localized MCC with pathologically confirmed negative lymph nodes treated with surgery. These data suggest that Mohs surgery may provide a more effective treatment for MCC primary tumors than conventional WLE, although the lack of randomization and potential for selection bias in this study highlight the need for future prospective work evaluating this issue.

Somatostatin receptor expression in Merkel cell carcinoma: correlation with clinical data

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, high-grade neuroendocrine neoplasm (NEN) of the skin. Somatostatin receptors (SSTRs) are G protein-linked receptors that regulate cell proliferation and growth. SSTRs are expressed in many NENs; however, scant information is available on their expression in MCCs or their association with clinical parameters and patient outcomes.

MATERIAL AND METHODS

This retrospective study was conducted at Helsinki University Hospital and the University of Helsinki. Using a tissue microarray, we investigated SSTR1-5 expression by immunohistochemistry in 99 MCC tissue samples. Samples were collected between 1983 and 2017 and coupled with the patients' clinical data.

RESULTS

SSTR2-SSTR5 were detected in 69%, 6%, 4%, and 1% of the tumours, respectively. However, SSTR1 expression was not observed. Cytoplasmic SSTR2 positivity was associated with metastatic disease at the time of diagnosis (p = 0.009), but it did not correlate with disease-specificity or overall survival.

CONCLUSION

SSTR2-5 expression was observed in MCCs. In particular, SSTR2 expression is clinically valid because it is associated with metastatic disease at the time of diagnosis and can thus serve as a prognostic marker. Moreover, SSTR2 overexpression provides a molecular basis for tumour imaging and treatment with somatostatin analogues.

Clinicopathological characteristics and prognosis of Merkel cell carcinoma: a single-center retrospective study in Korea

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin with high mortality. However, its clinical characteristics in Asian patients remain uncertain owing to its low incidence.

OBJECTIVE

To analyze the clinicopathological features of MCC and identify factors associated with its prognosis.

METHODS

The medical records of 62 patients with MCC were retrospectively reviewed. Data on clinical features, survival outcomes, prognostic factors, histopathology and immunohistochemical profile of the patients were collected and analyzed. Merkel cell polyomavirus status was evaluated using immunohistochemistry.

RESULTS

The incidence of MCC significantly increased over time. The mean duration of follow-up was 51.2 months, with an overall 5-year survival of 80.6%. More female patients with MCC were identified than male patients (1.3:1). Approximately half of the patients had stage I disease at the time of initial presentation. The primary tumor was frequently located in the lower extremities (40.3%), followed by the head and neck (32.3%), upper extremities (22.6%), and the trunk (4.8%). Male sex was associated with poorer overall survival (p = 0.003). Post-resection adjuvant radiotherapy significantly improved the overall survival (p = 0.023). Sentinel lymph node biopsy during surgery ameliorated the progression-free survival (p = 0.036) in patients with stage I or II cancer. Lymphovascular and perineural invasion were associated with a poor prognosis. Old age, immunohistochemical profiles, and Merkel cell polyomavirus-positivity were not associated with prognosis.

CONCLUSION

Post-surgical adjuvant radiotherapy and sentinel lymph node biopsy significantly improve the course of MCC.

Avelumab for the treatment of locally advanced or metastatic Merkel cell carcinoma-A multicenter real-world experience in Israel

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive malignancy of the skin, affecting predominantly the fair-skinned older population exposed to high levels of ultraviolet light. Immune suppression is considered a significant risk factor. With the recent advances in the field of immunotherapy, the treatment paradigm for advanced MCC, traditionally based on chemotherapy, has largely shifted to anti-PD-L1 and PD-1 agents such as avelumab and pembrolizumab, respectively. However, real-world data remain sparse. The aim of this study was to assess real-world evidence of the effectiveness of avelumab in a diverse group of patients with MCC in Israel.

METHODS

The electronic databases of five university hospitals in Israel were searched for all consecutive patients with MCC treated with at least one dose of avelumab in 2018-2022. Data on baseline, disease-related, treatment-related, and outcome parameters were collected and analyzed.

RESULTS

The cohort included 62 patients of whom 22% were immune-suppressed. The overall response rate to avelumab was 59%. The median progression-free survival was 8.1 months, and the median overall survival, 23.5 months, with no differences between immune-competent and immune-suppressed patients. Treatment was well tolerated; any-grade toxicity developed in 34% of patients, and grade 3-4 toxicity, in 14%.

CONCLUSIONS

Avelumab was found to be effective and safe for the treatment of advanced MCC in a diverse group of patients, including some with immune suppression. Further studies are warranted to evaluate the optimal sequence and duration of treatment and to assess the potential role of avelumab for earlier stages of MCC.

Incidence and prevalence of neuroendocrine neoplasms in Norway 1993-2021

The incidence of neuroendocrine neoplasms (NENs) has increased over the last decades. The prevalence of NENs has to a lesser extent been previously reported. We wanted to study the trends in incidence and prevalence of NEN in Norway from 1993 to 2021 through the Cancer Registry of Norway. This registry, which covers the whole population, has been found to be 99% complete. The neoplasms were classified as neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs). From 1993 to 2021 altogether 10.288 NETs and 13,982 (1.756 outside the lungs) NECs were diagnosed. The incidence of NETs increased from 3.72 to 9.97 per 100,000 per year, corresponding to a 268% increase, p < .001. The largest increase in incidence for NETs was found for pancreas (338%), lung (330%) and small intestine (303%). For NECs there was no change in the incidence, from 9.74 to 9.95 per 100,000 per year, p = .4, but there was an increase in the incidence of NECs originating from the skin (Merkel cell carcinoma) (287%), p < .001, and the GI tract (200%), p = .03. There were no changes in stage distribution at diagnosis for NETs and NECs. The prevalence for NENs increased 666% during the study period, NETs increased from 10.77 to 99.37 per 100.000 (927%), p < .001. For NECs the increase was from 7.4 to 21.56 per 100.000 (291%), p < .001. GI-NECs increased the most from 0.005 to 0.94 (1880%), p = .002. In conclusion, there was a substantial increase in incidence and prevalence of neuroendocrine neoplasms in Norway from 1993 to 2021. This is the first study to report complete prevalence of NENs for a whole nation.

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.

Merkel cell carcinoma: epidemiology, clinical features, diagnosis and treatment of a rare disease

Merkel cell carcinoma is a rare skin cancer with neuroendocrine differentiation. The risk factors include sun exposure, advanced age, immunosuppression (such as transplant recipients, patients with lymphoproliferative neoplasms, or patients with HIV), and Merkel cell polyomavirus infection. Clinically, Merkel cell carcinoma appears as a cutaneous or subcutaneous plaque or nodule, but this tumor diagnosis is rarely made clinically. Therefore, histopathology and immunohistochemistry are usually necessary. Primary tumors without evidence of metastases are treated with complete surgical excision and appropriate surgical margins. The presence of occult metastasis in a lymph node is frequent and a sentinel lymph node biopsy should be performed. Postoperative adjuvant radiotherapy increases local tumor control. Recently, agents that block the PD-1/PD-L1 pathway have shown objective and durable tumor regression in patients with advanced solid malignancies. The first anti-PD-L1 antibody used in patients with Merkel cell carcinoma was avelumab, but pembrolizumab and nivolumab have also shown efficacy. This article describes the current state of knowledge of the epidemiology, diagnosis, and staging of Merkel cell carcinoma, as well as new strategies for its systemic treatment.

Trends in incidence, treatment and survival of Merkel cell carcinoma in England 2004-2018: a cohort study

BACKGROUND

Merkel cell carcinoma (MCC) is a rare tumour with neuroendocrine differentiation and high associated mortality. Studies that describe the epidemiology of MCC are often limited by small sample size, short duration of follow-up, absence of nationwide data and paucity of data on different risk factors.

OBJECTIVES

To determine the incidence, demographics and survival for MCC in England between 2004 and 2018.

METHODS

This national retrospective cohort study identified all cases of MCC in England from 2004 to 2018 using national population-based data from the National Disease Registration Service. Crude counts, European age-standardized incidence rates (EASRs) and joinpoint analysis were conducted. Patient demographics and treatments received were described. Multivariable Cox regression analysis was used to study risk factors for MCC-specific mortality, by including a priori defined demographic factors, tumour characteristics and immunosuppression. Treatment data were not included in the Cox regression analysis.

RESULTS

A total of 3775 MCC tumours were registered. The median age at diagnosis was 81 years (interquartile range 74-87). Overall, 96·6% of patients identified as White ethnicity, and 8·3% of patients were immunosuppressed. The most common site was the face (27·4%). Patients most often presented with stage one disease (22·8%); however, stage was unknown in 31·0%. In total, 80·7% of patients underwent surgical excision, 43·5% radiotherapy and 9·2% systemic therapy. The EASR increased from 0·43 per 100 000 person-years (PYs) to 0·65 per 100 000 person-years between 2004 and 2018, representing a significant annual percentage change of 3·9%. The EASR was greater in men than in women for all years, with an overall male-to-female ratio of 1·41 : 1. The highest EASR was in South West England. Five-year disease-specific survival was 65·6% [95% confidence interval (CI) 63·8-67·4], with a median follow-up of 767 days. MCC-specific mortality increased with age [hazard ratio (HR) 1·02, 95% CI 1·02-1·03], deprivation (HR 1·43, 95% CI 1·16-1·76), immunosuppression (HR 2·80, 95% CI 2·34-3·34) and stage at diagnosis (HR 8·24, 95% CI 5·84-11·6).

CONCLUSIONS

This study presents the largest national MCC dataset in Europe, and the most complete reporting of MCC incidence and survival ever published. With the EASR of MCC increasing and high associated mortality, this study encourages further research into the pathology, diagnosis and therapeutic options for MCC to support management guidelines.

[Merkel Cell Carcinoma]

Merkel cell carcinoma represents a neuroendocrine tumour which can grow rapidly and metastasizes early. The median age of patients is 75-80 years. Given the continuously rising population age Merkel cell carcinoma is diagnosed more often. Besides surgery, radiotherapy and chemotherapy immunooncology plays an important role in the treatment of this aggressive tumour.

Merkel cell carcinoma: a forty-year experience at the Peter MacCallum Cancer Centre

BACKGROUND

Merkel cell carcinoma (MCC) is a rare but highly aggressive neuroendocrine skin malignancy, with Australia having the highest reported incidence in the world. There is currently a lack of consensus regarding optimal management of this disease.

METHODS

This was a retrospective audit conducted by reviewing existing medical records of MCC patients presenting to the Peter MacCallum Cancer Centre (PMCC) between 1980 and 2018. The primary endpoint was locoregional recurrence. The secondary endpoints were distant recurrence, disease-free survival (DFS) and overall survival (OS).

RESULTS

A total of 533 patients were identified. Locoregional recurrence occurring at one, two and 5 years was 24, 31 and 32%, respectively. The estimated 5-year OS and DFS were 46% (95% Confidence Interval [CI] 41-51%) and 34% (95% CI 30-39%) respectively. Older age at diagnosis (hazard ratio [HR] per year = 1.07, 95% CI 1.06-1.07, p < 0.001), and larger primary tumour diameter (HR =1.16, 95% CI 1.03-1.31, p = 0.019) were associated with worse OS on multivariable analysis. Positive or negative histopathological margin status was not associated with OS or DFS differences in patients treated with post-operative radiotherapy.

CONCLUSIONS

In our study, about a third of patients developed locoregional recurrence, distal recurrence or both, and there appears to be no change over the last four decades. If treated with adjuvant radiotherapy, there is no difference in OS or DFS with positive surgical margins. Findings should influence future guidelines.

Epidemiology of Merkel Cell Polyomavirus Infection and Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) is a ubiquitous virus replicating in human dermal fibroblasts. MCPyV DNA can be detected on healthy skin in 67−90% of various body sites, and intact virions are regularly shed from the skin. Infection occurs early in life, and seropositivity increases from 37 to 42% in 1- to 6-year-olds to 92% in adults. Merkel cell carcinoma (MCC) is a rare but very aggressive neuroendocrine tumor of the skin. It develops mainly on sun-exposed areas as a fast-growing, reddish nodule. Two MCC entities exist: about 80% of MCC are MCPyV-associated. Tumorigenesis is driven by viral integration into the host genome and MCPyV oncogene expression. In MCPyV-negative MCC, UV radiation causes extensive DNA damage leading to the deregulation of the cell cycle. In recent decades, MCC incidence rates have increased worldwide, e.g., in the United States, from 0.15 in 1986 to 0.7/100,000 in 2016. Risk factors for the development of MCC include male sex, older age (>75 years), fair skin, intense UV exposure, and immunosuppression. Projections suggest that due to aging populations, an increase in immunosuppressed patients, and enhanced UV exposure, MCC incidence rates will continue to rise. Early diagnosis and prompt treatment are crucial to reducing high MCC morbidity and mortality.

TRK Protein Expression in Merkel Cell Carcinoma Is Not Caused by NTRK Fusions

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous malignant tumor with neuroendocrine differentiation, with a rapidly growing incidence rate, high risk of recurrence, and aggressive behavior. The available therapeutic options for advanced disease are limited and there is a pressing need for new treatments. Tumors harboring fusions involving one of the neurotrophin receptor tyrosine kinase (NTRK) genes are now actionable with targeted inhibitors. NTRK-fused genes have been identified in neuroendocrine tumors of other sites; thus, a series of 76 MCCs were firstly analyzed with pan-TRK immunohistochemistry and the positive ones with real-time RT-PCR, RNA-based NGS, and FISH to detect the eventual underlying gene fusion. Despite 34 MCCs showing pan-TRK expression, NTRK fusions were not found in any cases. As in other tumors with neural differentiation, TRK expression seems to be physiological and not caused by gene fusions.

Merkel Cell Carcinoma of the External Ear: Population-Based Analysis and Survival Outcomes

(1) Background: Due to its highly aggressive behavior, the ability to identify and manage Merkel Cell Carcinoma (MCC) with a full understanding of its characteristics is essential. Because the external ear is an exposed area, resection can have dramatic consequences on patient’s self-image, which is why it is fundamental to detect MCC, typically found on UV-exposed regions such as the ears, at an early stage. (2) Methods: The Surveillance, Epidemiology, and End Results (SEER) database was searched for all external ear MCC between 2000 and 2019. A descriptive analysis based on frequencies was made to describe the demography of pathophysiologic features linked to MCC. Overall survival (OS) was studied and compared between variables with a log rank test. A multivariable Cox regression analysis was then computed to identify independent prognostic factors. (3) Results: A total of 210 patients (160 men) were identified with a median age of 80 years. The median OS was 47 months. Factors associated with lower OS included an age of over 80 years, the male gender, a tumor size of >5 cm, and metastatic disease. Gross (<1 cm) and wide (>1 cm) surgery excision margins were the surgery types with the best OS. (4) Conclusions: MCC of the external ear is diagnosed mostly in old men. Among the 182 patients who received a surgical procedure, gross and wide excision without radiotherapy were associated with the best OS.

Diagnosis and treatment of Merkel cell carcinoma: European consensus-based interdisciplinary guideline - Update 2022

Merkel cell carcinoma (MCC) is a rare skin cancer, accounting for less than 1% of all cutaneous malignancies. It is found predominantly in white populations and risk factors include advanced age, ultraviolet exposure, male sex, immunosuppression, such as AIDS/HIV infection, haematological malignancies or solid organ transplantation, and Merkel cell polyomavirus infection. MCC is an aggressive tumour with 26% of cases presenting lymph node involvement at diagnosis and 8% with distant metastases. Five-year overall survival rates range between 48% and 63%. Two subsets of MCC have been characterised with distinct molecular pathogenetic pathways: ultraviolet-induced MCC versus virus-positive MCC, which carries a better prognosis. In both subtypes, there are alterations in the retinoblastoma protein and p53 gene structure and function. MCC typically manifests as a red nodule or plaque with fast growth, most commonly on sun exposed areas. Histopathology (small-cell neuroendocrine appearance) and immunohistochemistry (CK20 positivity and TTF-1 negativity) confirm the diagnosis. The current staging systems are the American Joint Committee on Cancer/Union for international Cancer control 8th edition. Baseline whole body imaging is encouraged to rule out regional and distant metastasis. For localised MCC, first-line treatment is surgical excision with postoperative margin assessment followed by adjuvant radiation therapy (RT). Sentinel lymph node biopsy is recommended in all patients with MCC without clinically detectable lymph nodes or distant metastasis. Adjuvant RT alone, eventually combined with complete lymph nodes dissection is proposed in case of micrometastatic nodal involvement. In case of macroscopic nodal involvement, the standard of care is complete lymph nodes dissection potentially followed by post-operative RT. Immunotherapy with anti-PD-(L)1 antibodies should be offered as first-line systemic treatment in advanced MCC. Chemotherapy can be used when patients fail to respond or are intolerant for anti-PD-(L)1 immunotherapy or clinical trials.

Clinical-Pathological Evaluation and Prognostic Analysis of 228 Merkel Cell Carcinomas Focusing on Tumor-Infiltrating Lymphocytes, MCPYV Infection and ALK Expression

Merkel cell carcinoma is a rare and aggressive primary neuroendocrine carcinoma of the skin, whose pathogenesis can be traced back to UV radiation damage or Merkel cell polyomavirus (MCPyV) infection. Despite some improvements on the characterization of the disease partly due to its increased incidence, crucial pathogenetic and prognostic factors still need to be refined. A consecutive series of 228 MCC from three hospitals in Turin was collected with the aim of both analyzing the apparent increase in MCC incidence in our area and investigating the distribution and prognostic role of clinical-pathological parameters, with a focus on MCPyV status, ALK tumor expression and tumor infiltrating lymphocytes (TILs). Review of morphology and conventional immunohistochemical staining was possible in 191 cases. In 50 cases, the expression of the novel neuroendocrine marker INSM1 was additionally assessed. Fourteen cases of MCC of unknown primary skin lesion were identified and separately analyzed. While confirming an exponential trend in MCC incidence in the last decades and providing a description of histological and cytological features of a large series of MCC, the present study concludes that 1) INSM1 is a highly sensitive marker in both skin and lymph node primary MCC; 2) positive MCPyV status, brisk TILs and lower tumor size and thickness are independent positive prognostic parameters, and the combination of the former two may provide a novel tool for prognostic stratification; 3) ALK is expressed 87% of MCC and associated with positive viral status, and could represent a prognostic biomarker, if validated in larger series.

Lymph node ratio predicts efficacy of postoperative radiation therapy in nonmetastatic Merkel cell carcinoma: A population-based analysis

BACKGROUND

After radical resection of a nonmetastatic Merkel cell carcinoma (M0 MCC), postoperative radiation therapy (RT) is recommended as it improves survival. However, the role of RT in specific subgroups of M0 MCC is unclear. We sought to identify whether there is a differential survival benefit from RT in specific M0 MCC patient subgroups.

METHODS

M0 MCC patients from the Surveillance, Epidemiology, and End Results (SEER) database registry were collected. The best prognostic age, tumor size, and lymph node ratio (LNR, ratio between positive lymph nodes and resected lymph nodes) cutoffs were calculated. The primary endpoint was overall survival (OS).

RESULTS

A total of 5644 M0 MCC patients (median age 77 years, 62% male) were included: 4022 (71%) node-negative (N0) and 1551 (28%) node-positive (N+). Overall, 2682 patients (48%) received RT. Age > 76.5 years, tumor size >13.5 mm, and LNR >0.215 were associated with worse OS. RT was associated with longer OS in the M0 MCC, N0, and N+ group and independently associated with a 25%, 27%, and 26% reduction in the risk for death, respectively. RT benefit on survival was increased in tumor size >13.5 mm in the N0 group and LNR >0.215 in the N+ group. No OS benefit from RT was observed in T4 tumors (N0 and N+ groups).

CONCLUSIONS

RT was associated with improved survival in M0 MCC, irrespective of the nodal status. LNR >0.215 is a useful prognostic factor for clinical decision-making and for stratification and interpretation of clinical trials.

Merkelzellkarzinom

Das Merkelzellkarzinom ist ein aggressiver neuroendokriner Tumor, welcher durch schnelles Wachstum und frühzeitige Metastasierung charakterisiert ist. Das mediane Erkrankungsalter liegt zwischen 75–80 Jahren. Mit Zunahme des durchschnittlichen Bevölkerungsalters tritt der einstmals seltene Tumor immer häufiger auf. Neben den klassischen Therapiesäulen Chirurgie, Strahlentherapie und Chemotherapie spielt die Immunonkologie auch beim Merkelzellkarzinom eine zunehmend wichtige Rolle.

Gender and immunosuppression impact on Merkel cell carcinoma diagnosis and prognosis. A population based cohort study

Background

Merkel cell carcinoma (MCC), a rare cutaneous neuroendocrine endocrine tumour is increasing in incidence, and continues to carry a poor prognosis.

Objectives

The objectives of this study were to examine all Irish cases of MCC from 1 January 1994 over 2 decades, focusing on gender and organ transplantation recipients (OTRs). Cases were identified from the National Cancer Registry of Ireland. Covariates of interest included age, body site, period of diagnosis, deprivation‐status and history of non‐melanoma skin cancer (NMSC).

Results

In total 314 MCC cases were identified. A female predominance was noted (53.8%). Comparison between age‐standardised rates between the earliest period (1994–1996) with the latest period (2012–2014) showed an increase of 105% in total. The trend in age‐standardised incidence rates were noted to be increasing significantly (p = 0.0004). Average age at diagnosis was 77.6 years (male 75.1 years, female 79.7 years). Overall, the majority of MCC cases presented on the head and neck (n = 170, 54.1%). Differences in anatomical location of MCCs were noted between genders. Males were found to be more likely to have a history of previous NMSCs (males n = 73 [57.9%], females n = 53 [42.1%]). Thirty‐one percentage of patients died from MCC, average survival was 3.5 years in those who died of this malignancy. Ten organ transplant recipients developed MCC. OTR who developed MCC were diagnosed at a younger average age of 65.1 years. Standardized incidence ratio for MCC in OTR was 59.96. A higher proportion of OTR died from MCC (70%), with a shorter median survival of 0.14 years. In competing risks regression, gender was not significantly associated with risk of dying, females having a non‐significantly higher hazard of dying. Organ transplant recipients and patients from less deprived areas were at greater risk of dying from MCC.

Conclusions

This population based study provides epidemiological, clinical and outcome data for MCC over a 20‐year period.

Two Clinical Cases of Metastatic Merkel Cell Carcinoma Illustrating Avelumab Tolerability in Elderly Patients

We present two cases of primary cutaneous Merkel cell carcinoma in a 80-year and a 95-year old patient. Both patients had a wide local excision, but early recurrences occurred. Case 1 required palliative radiotherapy. He did not receive chemotherapy but case 2 did. They then proceeded to have immunotherapy with sustained responses lasting greater than 2 and 3 years. This report highlights an important new class of drug for the treatment of advanced Merkel cell carcinoma. Furthermore, our case report demonstrates that avelumab immunotherapy can be safely delivered to elderly patients, including 80- and 95-year-old patients. This report parallels the high and durable response rates to avelumab (including complete responses) that were shown in the JAVELIN phase II trials.

Merkel Cell Carcinoma: An Immunotherapy Fairy-Tale?

Merkel cell carcinoma (MCC) is a rare, highly aggressive, neuroendocrine cutaneous tumor. The incidence of MCC is growing worldwide, and the disease-related mortality is about three-fold higher than melanoma. Since a few years ago, very little has been known about this disease, and chemotherapy has been the standard of care. Nowadays, new discoveries about the pathophysiology of this neoplasm and the introduction of immunotherapy allowed to completely rewrite the history of these patients. In this review, we provide a summary of the most important changes in the management of Merkel cell carcinoma, with a focus on immunotherapy and a landscape of future treatment strategies.

Spontaneous Regression of Merkel Cell Carcinoma: Case Report

Merkel cell carcinoma (MCC) is a rare skin neuroendocrine tumor presumably arising from Merkel cells in the basal layer of epidermis. It is an aggressive tumor predominantly found on the head and neck area of elderly people, with a mortality rate around 41% for all stages. Complete spontaneous regression of MCC is seldom observed, mostly in elderly women. We describe complete spontaneous regression of large, histologically confirmed MCC in an elderly woman after biopsy, which occurred incidentally, while waiting for radical surgery with skin flap. Next-generation sequencing with SOPHiA Solid Tumor Plus Solution did not reveal any relevant gene mutations or rearrangements. An update of literature for these very rare cases is provided.

Multimodal Strategy in Localized Merkel Cell Carcinoma: Where Are We and Where Are We Heading?

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin whose incidence is rising. Multimodal treatment is crucial in the non-metastatic, potentially curable setting. However, the optimal management of patients with non-metastatic MCC is still unclear. In addition, novel insights into tumor biology and newly developed treatments (e.g., immune checkpoint inhibitors) that dramatically improved outcomes in the advanced setting are being investigated in earlier stages with promising results. Nevertheless, the combination of new strategies with consolidated ones needs to be clarified. We reviewed available evidence supporting the current treatment recommendations of localized MCC with a focus on potentially ground-breaking future strategies. Advantages and disadvantages of the different treatment modalities, including surgery, radiotherapy, chemotherapy, and immunotherapy in the non-metastatic setting, are analyzed, as well as those of different treatment modalities (adjuvant as opposed to neoadjuvant). Lastly, we provide an outlook of remarkable ongoing studies and of promising agents and strategies in the treatment of patients with non-metastatic MCC.

T-Cell Responses in Merkel Cell Carcinoma: Implications for Improved Immune Checkpoint Blockade and Other Therapeutic Options

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer with rising incidence and high mortality. Approximately 80% of the cases are caused by the human Merkel cell polyomavirus, while the remaining 20% are induced by UV light leading to mutations. The standard treatment of metastatic MCC is the use of anti-PD-1/-PD-L1-immune checkpoint inhibitors (ICI) such as Pembrolizumab or Avelumab, which in comparison with conventional chemotherapy show better overall response rates and longer duration of responses in patients. Nevertheless, 50% of the patients do not respond or develop ICI-induced, immune-related adverse events (irAEs), due to diverse mechanisms, such as down-regulation of MHC complexes or the induction of anti-inflammatory cytokines. Other immunotherapeutic options such as cytokines and pro-inflammatory agents or the use of therapeutic vaccination offer great ameliorations to ICI. Cytotoxic T-cells play a major role in the effectiveness of ICI, and tumour-infiltrating CD8⁺ T-cells and their phenotype contribute to the clinical outcome. This literature review presents a summary of current and future checkpoint inhibitor therapies in MCC and demonstrates alternative therapeutic options. Moreover, the importance of T-cell responses and their beneficial role in MCC treatment is discussed.

Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and extremely aggressive neuroendocrine carcinoma of the skin, with increasing incidence worldwide. This review intends to propose a comprehensive evaluation of MCC epidemiology, clinical features, pathogenetic mechanisms, diagnosis, and therapies. A section is dedicated to immunological aspects and another to the involvement of angiogenesis and angiogenic growth factors in MCC progression, proposing novel diagnostic and therapeutic approaches. Advanced MCC tumors have been treated with immune checkpoint inhibitors with effective results. Therefore, the state of art of this immunotherapy is also examined, reporting on the most recent clinical trials in the field. We conclude by underlining the achievements in the understanding of MCC pathology and indicating the present needs for effective diagnosis and therapeutic management of the disease.

A SEER analysis of survival and prognostic factors in merkel cell carcinoma of the head and neck region

While Merkel cell carcinoma (MCC) of the head and neck is highly malignant, it remains poorly characterized due to its rarity. The purpose of this study was to examine prognostic factors for overall survival (OS) and disease-specific survival (DSS) in patients with MCC of the head and neck region. The Surveillance, Epidemiology and End Results registry was reviewed for patients diagnosed between 1984 and 2016 with histologically confirmed, primary MCC of the head and neck region. A total of 2818 patients met the inclusion criteria, with a median age at diagnosis of 77 years. At five and 10 years, respectively, the OS was 42.4% and 25.1% and the DSS was 67.9% and 64.1%. Multivariate Cox analysis indicated that predictors of decreased DSS included age at diagnosis ≥75 years, white race, increasing tumor spread, lymph node involvement and either the lip or the scalp/neck as a primary site. When adjusting for the aforementioned factors, tumor depth was not found to be a prognostic factor for DSS. We anticipate these results will help clinicians to counsel patients regarding expectations and potential prognosis.

Immunotherapy in advanced Merkel cell carcinoma: Sydney west cancer network experience

INTRODUCTION

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with no survival benefit demonstrated using palliative cytotoxic chemotherapy in the setting of metastatic MCC. Recently, immune checkpoint inhibitors (anti-PD-L1/PD1) have been approved in this setting after durable clinical response was demonstrated in several clinical trials. In this series, we present a multicentre real-world experience in using anti-PD-L1/PD1 in advanced MCC.

METHODS

A retrospective review was performed of all patients with metastatic MCC who were treated with at least one dose of anti-PD-L1/PD1 presenting to Sydney West Cancer Network (Westmead, Nepean and Blacktown hospitals) was performed between 2016 and 2020. Treatment response was assessed based on morphologic and/or metabolic changes of the disease on FDG-PET/CT scans. Primary end point investigated was objective response rate. Secondary outcomes included therapy toxicity, disease control and overall survival.

RESULTS

Thirteen patients received anti-PD-L1/PD1 with a median age of 82 (range 62-89). Two patients had undergone prior palliative chemotherapy. The median follow-up time was 17 months (range 2-34). The overall, complete and partial response rates were 77% (10), 54% (7) and 23% (3), respectively. Treatment-related grade 1 or 2 toxicity was experienced by 69% with only 2 cases of greater severity. The median progression-free survival and overall survival were 18 months (95% CI 10-26 months) and 33 months (95% CI range 7.6-58.4 months), respectively.

CONCLUSIONS

Consistent with clinical trial results, anti-PD-L1/PD1 therapy in this small series demonstrated efficacy and safety in patients with metastatic MCC.

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.

Primary Merkel Cell Carcinoma: The Clinical Experience of Taipei Veterans General Hospital Revisited

BACKGROUND

Merkel cell carcinoma (MCC) is rare among Asians. To evaluate the presence and characteristics of MCC in Taiwan, we described the characteristics, treatment, and prognostic findings of MCC in our institution.

METHODS

We revisited and carried out a retrospective chart review of 16 consecutive patients with MCC treated from 1995 to 2018. Patient demographic data, tumor size, location, previous treatment, and follow-up data about presence of locoregional recurrence and metastasis were evaluated.

RESULTS

There were 14 male and 2 female patients (mean age = 75.1 years; range = 26-91 years). Clinical follow-up revealed local recurrences in 5 patients 1 to 4 months after surgical excision. Lymph node metastasis was observed in 3 patients. We reviewed previously published articles and analyzed the clinical findings, pathologic examinations, and treatments.

CONCLUSIONS

Surgical wide excision of the primary tumor remains the mainstay of treatment for patients with local/regional MCC. Additional management strategies, such as lymphadenectomy, radiotherapy, chemotherapy, and targeted therapy, depend on the presence or absence of clinically detectable lymph node disease. The prognosis for MCC is variable. Our findings highlight the importance of maintaining a high clinical suspicion for this malignancy in the appropriate clinical context to avoid delays in diagnosis and management.

International Increases in Merkel Cell Carcinoma Incidence Rates between 1997 and 2016

Relatively little is known about the epidemiology of Merkel cell carcinoma (MCC) with regard to international trends in incidence, specifically relating to differences by age, sex, and anatomic site. We examined the trends in sex-specific incidence of MCC in the United States, Australia, New Zealand, Scotland, and Norway over a 20-year period (1997-2016) as well as the site-specific incidence trends in the United States. We used Joinpoint regression models to estimate the average annual percentage change in the incidence. In the total United States population, we observed an average annual percentage change of 2.7% (95% confidence interval [CI] = 2.0-3.3) for MCC, with sex-specific incidence increasing from 0.55 to 1.03 per 100,000 in men and from 0.28 to 0.45 per 100,000 in women. MCC incidence also increased in Queensland, Australia (average annual percentage change 1.8%, 95% CI = 0.7-2.8), New Zealand (2.0%, 95% CI = 0.4-3.7), Scotland (3.7%, 95% CI = 2.0-5.5), and Norway (4.0%, 95% CI = 2.1-5.9). In all populations, MCC incidence was higher in men than in women. Between 1993 and 2016 in the United States, the incidence of MCC of the head and neck and upper and lower limbs increased in both sexes. Despite being an uncommon malignancy, our analyses show that MCC incidence is steadily increasing both in areas of low and those of high ambient UVR levels.

Merkel cell carcinoma: A systematic review of the demographic and clinical characteristics of 847 cases in Japan

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine carcinoma of the skin associated with Merkel cell polyomavirus and immunosuppression. Although MCC incidence is rising worldwide, MCC has not been sufficiently investigated in Japan. This study aimed to determine MCC demographics in Japan, including incidence, age, sex, location, spontaneous regression, and pure/combined MCC. Using PubMed and Igaku Chuo Zasshi, 847 MCC cases between 1985 and 2015 were extracted, and the main epidemiological characteristics were described. The mean age of all patients was 77.5 years. Regarding the characterized lesions, 63.0% were located on the head and neck, 5.2% on the trunk, 12.6% on the upper limb, 15.1% on the lower limb, 3.5% on the buttocks, and 0.6% on the genitals. Histopathological information regarding the presence of other malignancies could be retrieved in 611 cases, and a coexisting malignancy, mainly squamous cell carcinoma and Bowen's disease, was present in 14.2%. Subcutaneous MCC was observed in 31 patients with a male : female ratio of 1.07 (16 men/15 women). Nodal lesions with unknown primary tumor location were described in 19 patients with a male : female ratio of 0.9 (nine men/10 women) and a mean age of 77.7 years. Of 640 evaluable cases, spontaneous regression developed in 9.1%. Among those 58 patients, the male : female ratio was 1:2.1 in 56 evaluable cases (18 men/38 women). Merkel cell polyomavirus was assessed in 180 patients, and the virus was detected in 31.1% and not detected in 68.9% of the patients. MCC is a rare disease in Japan, with incidence rates and male : female ratios differing from those in the USA and European countries. Besides, this study reveals the high frequency of subcutaneous MCC and MCC with divergent differentiation patterns and spontaneous regression in Japan compared to other countries.

Merkel Cell Carcinoma of Unknown Primary: Immunohistochemical and Molecular Analyses Reveal Distinct UV-Signature/MCPyV-Negative and High Immunogenicity/MCPyV-Positive Profiles

Simple Summary

Merkel cell carcinomas (MCCs) of unknown primary are defined as deep-seated tumors without an associated cutaneous tumor. Although the distinction has important clinical implications, it remains unclear whether these tumors represent primary tumors of lymph nodes or metastatic cutaneous primaries. We compared the immunohistochemical profiles of four groups of Merkel cell carcinomas (virus-positive and virus-negative unknown primary tumors and virus-positive and virus-negative cutaneous tumors) and performed molecular studies on the unknown primary tumors. Virus-positive and virus-negative Merkel cell carcinomas of unknown primary (MCC-UPs) exhibited an immunoprofile similar to virus-positive and virus-negative primary cutaneous MCCs, respectively. Similar to primary cutaneous Merkel cell carcinomas, virus-negative unknown primary tumors exhibited UV signatures and frequent high tumor mutational burdens, whereas few molecular alterations were noted in virus-positive tumors. Although additional studies are warranted for the virus-positive cases, our findings are supportive of a cutaneous metastatic origin for virus-negative Merkel cell carcinomas of unknown primary.

Abstract

Background: Merkel cell carcinomas of unknown primary (MCC-UPs) are defined as deep-seated tumors without an associated cutaneous tumor. Although the distinction has important clinical implications, it remains unclear whether these tumors represent primary tumors of lymph nodes or metastatic cutaneous primaries. Methods: We compared the immunohistochemical profiles of four groups of MCCs (Merkel cell polyomavirus (MCPyV)-positive UP, MCPyV-negative UP, MCPyV-positive known primary (KP), and MCPyV-negative KP) using B-cell and pre-B-cell markers, cell cycle regulating proteins, follicular stem cell markers, and immune markers, and performed next generation and Sanger sequencing. Results: Virus-positive and virus-negative MCC-UPs exhibited an immunoprofile similar to virus-positive and virus-negative primary cutaneous MCCs, respectively. MCC-UP tumors (both virus-positive and -negative) were immunogenic with similar or even higher tumoral PD-L1 expression and intratumoral CD8 and FoxP3 infiltrates in comparison to MCPyV-positive cutaneous tumors. In addition, similar to primary cutaneous MCCs, MCPyV-negative MCC-UPs exhibited UV signatures and frequent high tumor mutational burdens, whereas few molecular alterations were noted in MCPyV-positive MCC-UPs. Conclusions: Our results showed distinct UV-signatures in MCPyV-negative tumors and high immunogenicity in MCPyV-positive tumors. Although additional studies are warranted for the MCPyV-positive cases, our findings are supportive of a cutaneous metastatic origin for MCPyV-negative MCC-UP tumors.

Assessment of Age, Period, and Birth Cohort Effects and Trends in Merkel Cell Carcinoma Incidence in the United States

Importance

Merkel cell carcinoma is an aggressive, cutaneous, neuroendocrine cancer that is increasing in incidence. Understanding why the incidence of Merkel cell carcinoma is increasing through underlying factors, such as age effects, calendar period of diagnosis effects, and birth cohort effects, can help guide resource allocation and design of screening programs.

Objectives

To evaluate the associations of patient age, calendar period of diagnosis, and birth cohort with the increasing incidence of Merkel cell carcinoma and to provide new incidence projections to 2030.

Design, Setting, and Participants

A cross-sectional retrospective study with age-period-cohort analysis and incidence projection modeling using data from the Surveillance, Epidemiology, and End Results Program database of 9 registries from 1987 to 2016 was conducted among 3720 patients with Merkel cell carcinoma. Statistical analysis was conducted from October 20, 2019, to July 29, 2020.

Exposures

Age effects (ie, physiology), period of diagnosis effects (ie, changes in diagnostics and clinical awareness), and birth cohort effects (ie, environmental risk factors) over time were assessed.

Main Outcomes and Measures

Incidence rates of Merkel cell carcinoma.

Results

Among the 3720 patients in the study (2200 male patients [59.1%]; median age, 77 years [interquartile range, 68-84 years]), during the period from 2012 to 2016, the age-adjusted Merkel cell carcinoma incidence rate was 0.66 per 100 000 (95% CI, 0.62-0.70), which represented a 3.5-times (95% CI, 3.0-4.2) increase from 1987 to 1991. The incidence of Merkel cell carcinoma increased with patient age across calendar periods and birth cohorts; the highest incidence rate was observed for those aged 85 years or older, with an age-adjusted rate from 2012 to 2016 of 14.6 per 100 000 for men and 5.5 per 100 000 for women. Although the birth cohort effect has continued to increase over time, the calendar period of diagnosis effect has started to plateau. It is projected that there will be 3023 new cases of Merkel cell carcinoma in 2020 and 5130 new cases in 2030, increased from an estimated 1933 cases in 2010.

Conclusions and Relevance

The slowing down of the period effect (ie, changes in diagnostics and awareness) found in this longitudinal cohort study suggests that part of the initial increased incidence of Merkel cell carcinoma was associated with increased detection. However, the projected increase in incidence rate is likely associated with the aging population and increasing risk factor exposure in more recent birth cohorts.