The Role of Sentinel Lymph Node Biopsy in the Management of Merkel Cell Carcinoma: A Systematic Review and Meta-analysis

Background

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy with high metastatic potential. Sentinel lymph node biopsy (SLNB) is used to assess locoregional spread, facilitate staging, and inform prognosis. Positive nodal status is associated with higher recurrence rates and reduced overall survival.

Methods

A systematic search was conducted. Eligible articles included patients diagnosed with MCC, who would be candidates for or who had SLNB. The Covidence tool was used for screening and data extraction, including additional treatments, disease-free survival, overall survival, and recurrence. Methodological quality was assessed using the Newcastle-Ottowa Scale criteria.

Results

SLNB was associated with increased likelihood of completion lymphadenectomy (223 versus 41), regional radiotherapy (2167 versus 808), and systemic chemotherapy (138 versus 31). Overall survival for patients undergoing SLNB was 81% at 2 years, 75% at 3 years, and 72% at 5 years (odds ratio: 0.79). Hazard ratio for positive SLNB versus negative was 3.36 (P < 0.001). Five-year disease recurrence was 23.3% in patients undergoing SLNB.

Conclusions

Lymph node metastases are associated with reduced overall survival and increased recurrence of MCC. Determining nodal status early can inform prognosis, facilitate staging, and determine need for adjuvant treatment. Adjuvant treatments are associated with reduced mortality and improved overall survival; SLNB is an important influencer of their use. Early prophylactic intervention should be considered in MCC in both positive and negative nodal status to improve overall outcomes. Widespread use of SLNB will allow more accurate assessment of the role of nodal status on adjuvant treatment and long-term outcomes.

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.

Primary tumor site for localized Merkel cell carcinoma drives different management strategies without impacting oncologic outcomes

BACKGROUND AND PURPOSE

Clinically localized Merkel cell carcinoma (MCC) has been associated with high rates of disease relapse. This study examines how primary tumor anatomic site drives patterns of care and outcomes in a large cohort treated in the contemporary era.

MATERIALS AND METHODS

Patterns of care and associated outcomes were evaluated for clinically Stage I-II MCC patients treated at our institution with adjuvant radiation therapy (RT) to the primary site and/or regional nodal basin as a component of their curative intent therapy between 2014-2021.

RESULTS

Of 80 patients who met inclusion criteria, the primary tumor anatomic site was head and neck (HN) for 42 (53%) and non-head and neck (NHN) for 38 (47%). Primary tumor risk factors were similar between cohorts. Fewer patients with HN tumors had wide local excision (WLE; HN-81% vs. NHN-100% p < 0.01). Of those undergoing WLE, patients with HN tumors received higher dose adjuvant RT (>50 Gy: HN-70% vs. NHN-8%; p < 0.01). Patients with HN tumors were less likely to undergo sentinel lymph node biopsy (HN-62%vs. NHN-100%; p < 0.01) and more likely to have elective nodal RT (HN-48% vs. NHN-0%). Despite varying management strategies, there was no significant difference in local recurrence-free survival (3-yr LRFS HN-94% vs. NHN-94%; p = 0.97), nodal recurrence-free survival (3-yr NRFS HN-89% vs. NHN-85%; p = 0.71) or overall recurrence-free survival (3-yr RFS 73% HN vs. 80% NHN; p = 0.44).

CONCLUSIONS

Among patients with primary MCC who had RT as a component of their initial treatment strategy, anatomically-driven heterogeneous treatment approaches were associated with equally excellent locoregional disease control.

Lymph Node Metastases from Non-Melanoma Skin Cancer of the Head and Neck

Non-melanoma skin cancer (NMSC) represents the most common malignancy in the world, comprising exceedingly common lesions such as basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) and rare lesions such as Merkel cell carcinoma. Risk factors are widely recognized and include ultraviolet (UV) light exposure, radiation exposure, immunosuppression, and many others. As a whole, survival and functional outcomes are favorable, but each histopathological subtype of NMSC behaves differently. Treatment regimens for the primary site usually include wide surgical excision and neck dissection in cases of clinically involved metastatic lymph nodes. The elective management of draining nodal basins, however, is a contested topic. Nearly all subtypes, excluding BCC, have a significant risk of lymphatic metastases, and have been studied with regard to sentinel lymph node biopsy (SLNB) and elective neck dissection. To date, no studies have definitively established a true single standard of care, as exists for melanoma, for any of the NMSCs. As a result, the authors have sought to summarize the current literature and identify indications and management options for the management of the cervical lymphatics for each major subtype of NMSC. Further research remains critically necessary in order to develop complete treatment algorithms.

Role of Sentinel Lymph Node Biopsy for Skin Cancer Based on Clinical Studies

The sentinel lymph node is the first lymph node from the primary tumor. Sentinel lymph node biopsy (SLNB) is a surgical procedure that can detect occult nodal metastasis with relatively low morbidity. It may also have a therapeutic effect via regional disease control. The Multicenter Selective Lymphadenectomy-I (MSLT-I) trial revealed a prognostic benefit from SLNB in melanoma patients. However, it remains unclear whether there is a prognostic benefit from SLNB in patients with nonmelanoma skin cancer owing to a lack of randomized prospective studies. Nevertheless, SLNB provides important information about nodal status, which is one of the strongest factors to predict prognosis and may guide additional nodal treatment. Currently, SLNB is widely used in the management of not only patients with melanoma but also those with nonmelanoma skin cancer. However, the utilization and outcomes of SLNB differ among skin cancers. In addition, SLNB is not recommended for routine use in all patients with skin cancer. In this review, we provide a summary of the role of SLNB and of the indications for SLNB in each skin cancer based on previously published articles.

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.

Current treatments and emerging therapies of human polyomavirus-associated skin diseases: a comprehensive review

Since Merkel cell polyomavirus (MCPyV) was linked as the predominant etiology of Merkel cell carcinoma (MCC) in 2008, three additional human polyomaviruses (HPyV) have been definitively linked to cutaneous diseases-trichodysplasia spinulosa virus (TSPyV) and human polyomavirus 6 and 7 (HPyV6, HPyV7). TSPyV contributes to the development of trichodysplasia spinulosa (TS), and HPyV6/7 is associated closely with the eruption of pruritic and dyskeratotic dermatoses (PDD). Clinically, MCC is treated with surgical excision and radiation with adjuvant chemotherapy, although newer treatment options include immune checkpoint inhibition. These novel immunotherapies hold promise for the treatment of metastatic MCC, but resistance and side effects prevent a significant proportion of patients from realizing their benefits. Based on previous case reports, the standard of care for the less deadly but disfiguring cutaneous disease TS include immunosuppressant (IS) reduction, the use of antivirals such as cidofovir (CDV) or valganciclovir (VGCV), or a combination of these treatments. Similar treatments were attempted for PDD, but oral acitretin was found to be most effective. As MCC, TS, and PDD are rare diseases, further research is required for effective treatments. In this review, we summarize clinical trials, preclinical studies, and case reports that present outcomes and side effects of current and emerging treatments for HPyV-associated cutaneous diseases, offering a comprehensive resource for clinical application and prospective clinical trials.

An Internally Validated Prognostic Risk-Score Model for Disease-Specific Survival in Clinical Stage I and II Merkel Cell Carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy for which factors predictive of disease-specific survival (DSS) are poorly defined.

METHODS

Patients from six centers (2005-2020) with clinical stage I-II MCC who underwent sentinel lymph node (SLN) biopsy were included. Factors associated with DSS were identified using competing-risks regression analysis. Risk-score modeling was established using competing-risks regression on a training dataset and internally validated by point assignment to variables.

RESULTS

Of 604 patients, 474 (78.5%) and 128 (21.2%) patients had clinical stage I and II disease, respectively, and 189 (31.3%) had SLN metastases. The 5-year DSS rate was 81.8% with a median follow-up of 31 months. Prognostic factors associated with worse DSS included increasing age (hazard ratio [HR] 1.03, p = 0.046), male sex (HR 3.21, p = 0.021), immune compromise (HR 2.46, p = 0.013), presence of microsatellites (HR 2.65, p = 0.041), and regional nodal involvement (1 node: HR 2.48, p = 0.039; ≥2 nodes: HR 2.95, p = 0.026). An internally validated, risk-score model incorporating all of these factors was developed with good performance (AUC 0.738). Patients with ≤ 4.00 and > 4.00 points had 5-year DSS rates of 89.4% and 67.2%, respectively. Five-year DSS for pathologic stage I/II patients with > 4.00 points (n = 49) was 79.8% and for pathologic stage III patients with ≤ 4.00 points (n = 62) was 90.3%.

CONCLUSIONS

A risk-score model, including patient and tumor factors, based on DSS improves prognostic assessment of patients with clinically localized MCC. This may inform surveillance strategies and patient selection for adjuvant therapy trials.

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.

Head and Neck Merkel Cell Carcinoma: A 12-Year Single Institutional Experience

Background

Merkel cell carcinoma (MCC) is an aggressive malignancy of presumed neuroendocrine origin. Most case series of MCC are limited by low case numbers and are not specific to head and neck tumours. The purpose of this study was to provide a focused review of head and neck MCC diagnosis and management in a single Irish institution.

Methods

Patient's demographics, tumour characteristics, pathological diagnosis, surgical treatment, adjuvant treatment, subsequent management and clinical course were collected. Estimates of progression-free MCC survival rates were calculated by the Kaplan–Meier statistical model. A Pearson product-moment correlation coefficient examined the association between surgical margins and disease-free follow-up.

Results

In total, 11 patients were treated for head and neck MCC with a mean age of 79.6 years (range = 69–91 years). The mean average follow-up duration of patients was 18.3 months. Of the cohort, 18% (n=2) had a sentinel node biopsy (SLNB). A selective neck dissection was subsequently performed in 18% (n=2). In total, 72% (n=8) of patients received adjuvant radiotherapy. Median disease-specific survival was 15 months for the SLNB group and 17 months for the non-SLNB group, not statistically significant (p=0.23). There was no significant association between surgical margins and disease-free follow (p=0.65).

Conclusions

Our case series adds to a limited body of evidence of head and neck MCC. Surgery remains the treatment priority in localized disease, with an increasing role of SLNB for accurate prognostication and staging. Early management of stage I disease results in moderate long-term disease-free survivability.

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.

Viruses and Skin Cancer

Advances in virology and skin cancer over recent decades have produced achievements that have been recognized not only in the field of dermatology, but also in other areas of medicine. They have modified the therapeutic and preventive solutions that can be offered to some patients and represent a significant step forward in our knowledge of the biology of skin cancer. In this paper, we review the viral agents responsible for different types of skin cancer, especially for solid skin tumors. We focus on human papillomavirus and squamous cell cancers, Merkel cell polyomavirus and Merkel cell carcinoma, and human herpesvirus 8 and Kaposi’s sarcoma.

Sentinel Node Biopsy for Nonmelanoma Skin Cancer of the Head and Neck

Sentinel lymph node biopsy has the potential to impact regional control and survival for high-risk cutaneous malignancy. The outcome of sentinel lymph node biopsy is a potential guide for treatment and surveillance. The population of high-risk nonmelanoma patients that will benefit from sentinel lymph node biopsy remains to be determined. Any cutaneous malignancy with a greater than 10% risk of occult metastasis should be considered for sentinel lymph node biopsy or active surveillance. Localized cutaneous squamous cell carcinoma lesions with multiple high-risk features and nearly all patients with localized Merkel cell carcinoma should be considered for sentinel lymph node biopsy.

Does regional lymph node status have a predictive effect on the prognosis of Merkel cell carcinoma?

BACKGROUND

There is no article that studies whether the regional lymph node (RLN) status affects the prognosis of Merkel cell carcinoma (MCC).

METHODS

The survival and disease data of MCC patients were obtained from the Surveillance, Epidemiological, and End Results (SEER) database. The overall survival (OS) and cause-specific survival (CSS) rates were endpoints.

RESULTS

A total of 1822 patients were included, with a mean age of 72.5 years. The number of RLN-positive patients was 862 (47.3%), and the number of RLN-negative patients was 960 (52.7%). The regression analysis showed that primary site, sex, and tumor size were statistically significant and independent predictors of RLN status. The five-year OS and CSS of RLN-negative patients were 71.4% and 92.3%, respectively, which were much higher than those of RLN-positive patients (37.5% and 65.8%, respectively) (P <0.001). In univariate survival analysis, positive RLN significantly predicted deterioration of OS and MSS (P <0.001). In multivariate analysis, RLN status had no statistically significant effect on patient prognosis.

CONCLUSION

The prognosis of patients with RLN metastasis is worse than that of patients without RLN metastasis, but RLN status is not an independent predictor of the prognosis of patients with MCC.

Primary Treatment Selection for Clinically Node-Negative Merkel Cell Carcinoma of the Head and Neck

OBJECTIVE

Merkel cell carcinoma practice guidelines recommend sentinel lymph node biopsy after wide local excision for the initial management of clinically node-negative disease without distant metastases (cN0M0). Despite guideline publication, treatment selection remains variable. We hypothesized that receipt of guideline-recommended care would be more common in patients evaluated at academic centers and institutions with high melanoma case volumes and that such therapy would be associated with improved overall survival.

STUDY DESIGN

Retrospective cohort analysis.

SETTING

The National Cancer Database from 2004 to 2015.

METHODS

A total of 3500 patients were included. We utilized Kaplan-Meier analysis and logistic and Cox proportional hazard regressions. Survival analysis was performed on inverse probability-weighted cohorts.

RESULTS

There has been a trend toward evaluation at academic programs at a rate of 1.58% of patients per year (95% CI, 1.06%-2.11%) since 2004. However, the percentage of patients receiving guideline-compliant primary tumor excision and lymph node evaluation has plateaued at approximately 50% since 2012. Guideline-compliant surgical management was more commonly provided to patients evaluated at academic programs than nonacademic programs but only when those institutions had a high melanoma case volume (odds ratio, 2.01; 95% CI, 1.62-2.48). Receipt of guideline-compliant primary tumor excision and lymph node evaluation was associated with improved overall survival (hazard ratio, 0.70; 95% CI, 0.64-0.76).

CONCLUSION

Facility factors affect rates of receipt of guideline-compliant initial surgical management for patients with node-negative Merkel cell carcinoma. Given the survival benefit of such treatment, patients may benefit from care at hospitals with high melanoma case volumes.

Merkel Cell Carcinoma: A Description of 11 Cases

Merkel cell carcinoma (MCC) is a malignant neuroendocrine tumor. Metastasis or lymph node spread is often detected at diagnosis. We performed a descriptive, retrospective study of patients diagnosed with MMC at Hospital Universitario Fundación Alcorcón in the Community of Madrid, Spain between January 1998 and December 2018. Eleven patients (7 men [63%] and 4 women [36%]; mean age, 77.6 years) were diagnosed with MCC during this 21-year period; 45% of patients had stage IIIB disease (pTNM) at diagnosis. All patients but one underwent local surgery, and lymphovascular invasion was detected in 7 cases. Eight patients received adjuvant therapy after surgery (radiation therapy in 5 cases and chemotherapy in 3). Six patients (54%) died of MCC (mean survival, 14.5 months). MCC is an uncommon malignant tumor with an annual incidence of around 0.18 to 0.41 cases per 100 000 inhabitants; this is similar to the rate of 0.29 to 0.32 cases per 100 000 inhabitants a year detected in our series. Results with avelumab, a drug recently approved for the treatment of metastatic MCC; have been promising.

Effect of Sentinel Lymph Node Biopsy and LVI on Merkel Cell Carcinoma Prognosis and Treatment

OBJECTIVE

Prognostic factors and optimal treatment approaches for Merkel cell carcinoma (MCC) remain uncertain. This study evaluated the influences of sentinel lymph node (SLN) biopsy and lymphovascular invasion (LVI) on treatment planning and prognosis.

STUDY DESIGN

Retrospective cohort study.

METHODS

Stage 1 to 3 MCC patients treated 2005 to 2018. Predictors of nodal radiation were tested using logistic regression. Predictors of recurrence-free, disease-specific, and overall survival were tested in Cox proportional hazard models.

RESULTS

Of 122 patients, 99 were without clinically apparent nodal metastases. Of these, 76 (77%) underwent excision and SLN biopsy; 29% had metastasis in SLNs, including 20% of MCCs 1 cm or less. Primary tumor diameter, site, patient age, gender, and immunosuppressed status were not significantly associated with an involved SLN. Among patients who underwent SLN biopsy, 13 of 21 (62%) MCCs with LVI had cancer in SLNs compared with 14 of 44 (25.5%) without LVI (P = .003). Although local radiation was common, nodal radiation was infrequently employed in SLN negative (pathologic N0) patients (21.8% vs. 76.2% for patients with SLN metastases, P = .0001). Survival of patients with positive SLNs was unfavorable, regardless of completion lymphadenectomy and/or adjuvant radiation. After accounting for tumor (T) and node (N) classification, age, immunosuppression, and primary site, a positive SLN and LVI were independently associated with worse survival (LVI/recurrence-free survival [RFS]: hazard ratio [HR] 2.3 (1.04-5, P = .04; LVI/disease-specific survival [DSS]: HR 5.2 (1.8-15, P = .007); N1a vs. pN0/RFS HR 3.6 (1.42-9.3, P = .007); DSS HR5.0 (1.3-19, P = .17).

CONCLUSION

SLN biopsy assists in risk stratification and radiation treatment planning in MCC. LVI and disease in SLNs, independently associated with worse survival, constitute markers of high-risk disease warranting consideration for investigational studies.

LEVEL OF EVIDENCE

III Laryngoscope, 131:E828-E835, 2021.

Merkel Cell Carcinoma - Current Controversies and Future Directions

Merkel cell carcinoma is a rare, aggressive neuroendocrine skin malignancy. Evidence for management comes from case series and single-arm trials. Optimal outcomes require assessment of the patient in a multidisciplinary team setting. Rapid diagnosis and staging are essential for locoregional control and may reduce metastasis. Sentinel lymph node biopsy (SLNB) adds prognostic information. FDG-positron emission tomography has high sensitivity and specificity and affects management in a quarter of cases. Surgical excision and radiotherapy provide good locoregional control even with positive margins. Wide surgical margins are needed if adjuvant radiotherapy is not used. It is uncertain whether adjuvant radiotherapy or elective surgery for uninvolved nodes or for patients selected by positive SLNB improves survival. Total doses of 50 Gy provide high levels of control for microscopic disease but at least 60 Gy should be given for macroscopic disease. Chemotherapy can be given safely with radiotherapy, but the benefit of adjuvant chemotherapy remains uncertain. Trials of adjuvant immune therapy are underway. Unresectable primaries might be controlled with radiotherapy alone or combination systemic therapy, radiotherapy and surgery. Metastatic disease often responds to chemotherapy, but the response duration can be short. Immunity is central to disease control. Immune checkpoint inhibitor treatment resulted in high response rates in chemotherapy-naive patients and lower rates in chemotherapy-refractory patients. Durable responses are observed.

Merkel Cell Carcinoma Review

Merkel cell carcinoma is a rare and aggressive cutaneous malignancy of neuroendocrine origin-an often-missed diagnosis due to the wide histopathologic differential diagnosis of malignant small blue cell tumors. The advent of electron microscopy and immunohistochemistry staining for cytokeratin 20, a shared neuroendocrine marker, greatly improved diagnostic accuracy. Over the past decade, staging, treatment, and surveillance of the cancer have progressed at a remarkably rapid pace. Herein, the authors provide an update on the current guidelines around diagnosis and management and review the exciting advancements on the horizon.

Frequency and prognosis of metastasis to liver, lung, bone and brain from Merkel cell carcinoma

Aim: To describe the factors affecting distant metastasis of Merkel cell carcinoma (MCC) and the prognosis of metastatic MCC. Materials & methods: The MCC patient information was downloaded from the SEER database. Logistic regression and Cox proportional hazard models were conducted to screen for significant factors. Results: A total of 3449 patients were enrolled. Surgery and chemotherapy were significantly correlated with the occurrence of distant metastasis. In the cause-specific survival rate of MCC, regional lymph node removal, sentinel lymph node biopsy, radiation and chemotherapy can significantly reduce the prognostic risk of patients with distant metastases. Conclusion: Our study screened out the factors affecting the distant metastasis and prognosis of MCC and more prospective studies are needed to verify our findings.

Surgical management of non melanoma skin cancer of the head and neck

Non-melanoma skin cancer (NMSC) is the most common malignancy in the world and is reaching epidemic proportions. The most common types of NMSC include basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The head and neck is the most common site for NMSC, and surgery remains the mainstay of treatment. We review the etiology, risk factors, pathogenesis as well as the preoperative, operative, and postoperative considerations in the management of NMSC. Multidisciplinary evaluation and attention to each of these phases is imperative for favorable oncologic and functional patient outcomes.

Merkel cell carcinoma in Taiwan: A series of 24 cases and literature review

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine carcinoma of the skin. The available reports of MCC in Asia are limited; in this study, we report the largest series of MCC in Taiwan to date.The series is composed by 24 pathologically proven MCC cases, which were retrospectively reviewed in Chang Gung Memorial Hospital in Taiwan between 2000 and 2018.The tumor occurred predominantly in men (80%) and in the elderly (median 74.8 years). Twenty-one patients had locoregional MCC and 3 had metastatic MCC at the time of diagnosis. Patients with pathologically proven negative nodes by sentinel lymph node biopsy (SLNB) showed better survival time than those without SLNB in 16 clinically node-negative MCC cases undergoing primary surgery. Salvage surgery for loco-regional recurrence lengthened the survival time and possibly cured recurrent MCC. Palliative chemotherapy with cisplatin and etoposide showed a response rate of 25%, progression-free survival of 3.6 months, and overall survival of 14.8 months in 4 metastatic/recurrent MCC. Avelumab treatment was effective in 1 patient, who achieved a durable disease control.This observational cohort of MCC patients in Taiwan suggests aggressive surgical intervention including wide excision and lymph node management, salvage operation is critical for early MCC patients, and palliative chemotherapy and immunotherapy showed their efficacy for advanced MCC patients.

S2k guidelines for Merkel cell carcinoma (MCC, neuroendocrine carcinoma of the skin) - update 2018

Merkel cell carcinoma (MCC, ICD-O M8247 / 3) is a rare malignant primary skin tumor with epithelial and neuroendocrine differentiation. The neoplastic cells share many morphological, immunohistochemical and ultrastructural characteristics with Merkel cells of the skin. The diagnosis of MCC is rarely made on clinical grounds. Histological and immunohistochemical studies are usually required to confirm the clinical suspicion. Given the frequent occurrence of occult lymph node metastasis, sentinel lymph node biopsy should be performed once distant metastasis has been ruled out by cross-sectional imaging. Primary tumors without evidence of organ metastases are treated with complete surgical excision with appropriate surgical margins. Radiation therapy should be considered at all stages of the disease. For advanced MCC that is no longer amenable to curative treatment by surgery or radiation therapy, there is currently no established systemic therapy for which an improvement in recurrence-free survival or overall survival has been demonstrated in a prospective randomized trial. However, immunotherapy using PD-1/PD-L1 blockade seems to be superior to chemotherapy. Various factors warrant that further diagnostic and therapeutic interventions be determined by an interdisciplinary tumor board. These factors include the tumor's aggressiveness, the frequent indication for sentinel lymph node biopsy along with the frequent occurrence in the head and neck region, the potential indication for adjuvant radiation therapy as well as the complexity of the required diagnostic workup.

Sentinel lymph node biopsy in Merkel cell carcinoma: Predictors of sentinel lymph node positivity and association with overall survival

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, aggressive malignancy with high rates of recurrence and metastasis.

OBJECTIVE

To evaluate predictors of sentinel lymph node (SLN) positivity in MCC using the National Cancer Database.

METHODS

The National Cancer Database, from 2012 to 2014, was used to identify 3048 patients with MCC, of whom 1174 received an SLN biopsy. Predictors of SLN positivity were evaluated using logistic regression. Overall survival was evaluated using a Cox proportional hazards model.

RESULTS

Of patients who underwent SLN biopsy, those with primary lesions on the trunk (odds ratio, 1.98; 95% confidence interval [CI], 1.23-3.17; P = .004), tumor-infiltrating lymphocytes (odds ratio, 1.58; 95% CI, 1.01-2.46; P = .04), or lymphovascular invasion (odds ratio, 3.45; 95% CI, 2.51-4.76; P < .001) were more likely to have positive SLNs on multivariate analysis. Overall survival was negatively affected by age ≥75 years (hazard ratio [HR], 2.55; 95% CI, 1.36-4.77; P = .003), male sex (HR, 1.78; 95% CI, 1.09-2.91, P = .022), immunosuppression (HR, 3.51; 95% CI, 1.72-7.13; P = .001), and SLN positivity (HR, 3.15; 95% CI, 1.98-5.04; P < .001).

LIMITATIONS

Lack of disease-specific survival and potential selection bias from a retrospective data set.

CONCLUSIONS

Truncal MCC, tumor-infiltrating lymphocytes, and presence of lymphovascular invasion were independent predictors of positive SLNs. Overall survival was negatively affected by advancing age, male sex, immunosuppression, and SLN positivity.

[Update in treatment for Merkel Cell Carcinoma and clinical practice guide]

Merkel Cell Carcinoma (MCC) is a rare neuroendocrine skin cancer that is associated with frequent recurrences and a high mortality rate. In the recent past years, incidence rates of MCC have increased in the USA, Australia and Europe. About one third of patients present metastatic disease at the time of diagnosis or will develop metastases in the course of their disease. Although advanced MCC is chemosensitive, responses to cytotoxic chemotherapy are mostly of short duration and toxicity is potentially high. Recently, considerable progress has been made in the MCC field with the arrival of immunotherapy, particularly anti-PD-1 and anti-PD-L1 antibodies which have demonstrated impressive frequency and durability of response and were well-tolerated. However, about 50 % of advanced patients do not respond to immunotherapy and urgent need exists to identify biomarkers and predictive factors. Moreover, many randomized prospective studies are evaluating the efficacy and safety of novel therapeutics and patients with advanced stages are encouraged to participate in clinical trials. This article synthetizes the actual clinical practice guidelines, the safety and efficacy data from the recent clinical trials and the on-going clinical trials to help clinicians in the treatment of MCC patients.

Merkel cell carcinoma: Epidemiology, pathogenesis, diagnosis and therapy

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer with a neuroendocrine phenotype. Incidence varies according to the geographic regions but is overall increasing. Different risk factors have been identified namely advanced age, immunosuppression, and ultraviolet light exposure. An association between MCC and polyomavirus infection is known. However, the exact mechanism that leads to carcinogenesis is yet to be fully understood. Surgery when feasible is the recommended treatment for localized disease, followed by adjuvant radiation or chemoradiation. In the metastatic setting, chemotherapy has been the standard treatment. However, two recently published trials with immune checkpoint inhibitors in first and second line showed promising results with a tolerable safety profile and these might become the standard therapy shortly. Somatostatin receptors are expressed in many MCC but such expression is not associated with disease severity. Presently there are no biomarkers predictive of response that could help to better select patients to these new therapies, and additional research is essential.

Recent Insights and Advances in the Management of Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine malignancy with a propensity for recurrence and a poor prognosis. Incidence of MCC is on the rise and is known to increase with advanced age, immunosuppression, and UV exposure. Merkel cell polyomavirus is implicated in the pathogenesis of virus-positive MCC and accounts for 80% of MCCs in the northern hemisphere and 25% in southern latitudes. In contrast, tumorigenesis of virus-negative MCC is linked to UV-induced DNA damage. Interplay between ubiquitous Merkel cell polyomavirus skin infections that commonly occur in healthy skin and other established risk factors, such as immunosuppression and UV exposure, remains poorly understood. Surgery and radiotherapy achieves excellent locoregional control; however, invariably, a significant proportion of patients develop disseminated disease that is incurable. Chemotherapy offers a high response rate for metastatic disease, but responses are short-lived and the impact on survival is not established. Recent advances in our understanding of the genetic landscape and immunobiology of MCC has led to investigation of novel treatments, including immune checkpoint inhibitors, which are likely to rapidly transform the way we manage these patients. We review epidemiologic, clinical, and histopathologic features of MCC; describe recent insights in MCC biology; and discuss novel therapeutic approaches.

Prognostic factors in Merkel cell carcinoma patients undergoing sentinel node biopsy

INTRODUCTION

Debate remains about prognostic factors in primary Merkel cell carcinoma (MCC). We investigated clinicopathological factors as determinants of survival in patients with MCC submitted to sentinel node biopsy.

METHODS

Sixty-four consecutive patients treated for a primary MCC were identified from a prospectively maintained database at Fondazione IRCCS Istituto Nazionale dei Tumori, Milan. Time to events outcome were described by product limit estimators and proportional hazards model was used to investigate the association between outcome and potential predictors.

RESULTS

The most common site of primary tumor was lower limbs (56.3%). The size of primary lesion was ≤2 cm in 67.2% of cases. Presence of residual disease after the diagnostic surgical excision was observed in 28% of cases. All patients received sentinel node biopsy (SNB) and a SN positivity was detected in 26.6%. The median follow up was 78 months. Disease recurrence occurred in 17 patients (26.6%). In the SN negative group 10 recurrences occurred (21.3%), whereas 7 (41.2%) were found in SN positive one. Nine patients SN negative (19.1%) died of disease and 3 (17.6%) among SN positive. SN status was not associated with survival (p = 0.78). Neither age, gender, size and site of primary tumor resulted predictors of patients' outcome. The presence of residual tumor in the specimen of the wide local excision, after the diagnostic surgical excision, was the only variable associated with survival (p = 0.03).

CONCLUSIONS

Presence of residual tumor in the specimen of the wide local excision is the main prognostic factor in MCC patients.

Postoperative radiation therapy is associated with a reduced risk of local recurrence among low risk Merkel cell carcinomas of the head and neck

PURPOSE

Merkel cell carcinoma (MCC) is a rare and often aggressive skin cancer. Typically, surgery is the primary treatment. Postoperative radiation therapy (PORT) is often recommended to improve local control. It is unclear whether PORT is indicated in patients with favorable Stage IA head and neck (HN) MCC.

METHODS AND MATERIALS

We conducted a retrospective analysis of 46 low-risk HN MCC cases treated between 2006 and 2015. Inclusion criteria were defined as a primary tumor size of ≤ 2 cm, negative pathological margins, negative sentinel lymph node biopsy, and no immunosuppression. Local recurrence (LR) was defined as tumor recurrence within 2 cm of the primary surgical bed and estimated with the Kaplan-Meier method.

RESULTS

Omission of PORT was offered to all 46 patients, of which 23 patients received PORT and 23 did not. No patient received adjuvant chemotherapy. There were no significant differences in surgical margins, tumor size, depth, lympho-vascular invasion status, or demographics between the two patient groups. Median follow-up for all patients was 3.7 years. Six of the 23 patients who did not receive PORT developed an LR. Compared to the group that received PORT, there was a significantly higher risk of LR in the group treated without PORT (26% vs. 0%, P = .02). Median time to LR was 11 months. All local failures were effectively salvaged. There was no difference in MCC-specific and overall survival between the 2 groups.

CONCLUSIONS

For patients with HN MCC, omission of PORT was associated with a significantly higher risk of local recurrence even among those patients with the lowest-risk tumors (i.e., Stage IA without immune suppression). Thus, it is important to weigh the benefits of PORT against the side effect profile on a case-specific basis for each patient.

Analysis of Prognostic Factors from 9387 Merkel Cell Carcinoma Cases Forms the Basis for the New 8th Edition AJCC Staging System

BACKGROUND

The first consensus Merkel cell carcinoma (MCC) staging system was published in 2010. New information on the clinical course prompts review of MCC staging.

METHODS

A total of 9387 MCC cases from the National Cancer Data Base Participant User File with follow-up and staging data (1998-2012) were analyzed. Prognostic differences based on clinical and pathological staging were evaluated. Survival estimates were compared by disease extent.

RESULTS

Sixty-five percent of cases presented with local disease, whereas 26 and 8 % presented with nodal and distant disease. Disease extent at presentation was predictive of 5-year overall survival (OS) with estimates of 51, 35, and 14 % for local, nodal, and distant disease. Tumor burden at the regional nodal basin was predictive of 5-year OS with estimates of 40 and 27 % for clinically occult and clinically detected nodal disease. For local disease, we confirm improved prognosis when the regional nodal basin was negative by pathological compared with clinical staging. We identified 336 cases with clinically detected nodal disease and unknown primary tumor and showed improved prognosis over cases presenting with concurrent primary tumor (OS estimates of 42 vs. 27 %).

CONCLUSIONS

Analysis of a national dataset of MCC cases validates the predictive value of disease extent at presentation. Separation of clinical and pathological stage groups and regrouping of unknown primary tumors are supported by the analysis. The revised staging system provides more accurate prognostication and has been formally accepted by the AJCC staging committee for inclusion in the 8th edition.

Research methods to change clinical practice for patients with rare cancers

Rare cancers are a growing group as a result of reclassification of common cancers by molecular markers. There is therefore an increasing need to identify methods to assess interventions that are sufficiently robust to potentially affect clinical practice in this setting. Methods advocated for clinical trials in rare diseases are not necessarily applicable in rare cancers. This Series paper describes research methods that are relevant for rare cancers in relation to the range of incidence levels. Strategies that maximise recruitment, minimise sample size, or maximise the usefulness of the evidence could enable the application of conventional clinical trial design to rare cancer populations. Alternative designs that address specific challenges for rare cancers with the aim of potentially changing clinical practice include Bayesian designs, uncontrolled n-of-1 trials, and umbrella and basket trials. Pragmatic solutions must be sought to enable some level of evidence-based health care for patients with rare cancers.

Merkel cell carcinoma: value of sentinel lymph-node status and adjuvant radiation therapy

BACKGROUND

Sentinel lymph-node (LN) biopsy (SLNB) is a valuable tool to assess the regional LN status in Merkel cell carcinoma (MCC). However, its prognostic value is still debated. This study was undertaken to assess SLNB usefulness for MCC management and to determine the impact of SLNB status on disease-free survival (DFS) and overall survival (OS) by comparing SLNB-positive versus -negative patients according to demographic, clinical and treatment characteristics.

PATIENTS AND METHODS

In this retrospective, multicenter observational study, SLNB was proposed to all patients referred for clinically N0 MCC. Treatment schedule consisted of wide-margin surgical resection of primary MCC followed by adjuvant radiation therapy (aRT) to the primary site and, for SLNB-positive patients, radical LN dissection followed by regional aRT. Univariate and multivariate analyses determined factors associated with DFS and OS.

RESULTS

Among 87 patients with successful SLNB, 21 (24.1%) were SLNB-positive. Median follow-up for the entire series was 39 months; respective 3-year DFS and OS rates were 73% and 81.4%, respectively. Univariate analysis (all patients) identified SLNB-negativity as being associated with prolonged OS (P = 0.013) and aRT (all sites considered) was associated with longer DFS (P = 0.004) and OS (P = 0.018). Multivariate analysis (all patients) retained SLNB status and aRT (all sites considered) as being associated with improved DFS (P = 0.014 and 0.0008) and OS (P = 0.0020 and 0.0019). Moreover, for SLNB-negative patients, tumor-bed irradiation was also significantly associated with prolonged DFS (P = 0.006) and OS (P = 0.014).

CONCLUSIONS

The present study demonstrates that SLNB-negativity is a strong predictor of longer DFS and OS in stage I and II MCC patients. The similar benefit for aRT on tumor bed observed in this study has to be confirmed by a prospective study. The results advocate for SLNB being considered to all MCC patients.

Sentinel lymph node biopsy in Merkel cell carcinoma: a 15-year institutional experience and statistical analysis of 721 reported cases

Merkel cell carcinoma (MCC) is a rare aggressive cutaneous neuroendocrine malignancy that frequently metastasizes to the regional lymphatic basin. Pathological assessment of regional lymph nodes with sentinel lymph node biopsy (SLNB) in patients without clinical involvement has permitted more accurate staging and more appropriate management. Nonetheless, concerns have been raised regarding the accuracy of this technique and its prognostic implications. We conducted a review of previously published data analysing the positive and false negative rates of SLNB in MCC. A search of the Medline and Embase databases to April 2015 identified 36 published studies between 1997 and 2015 comprising 692 patients. With the addition of 29 patients treated at our own institution, we conducted an analysis of 721 patients. Among this cumulative cohort, SLNBs were performed from 736 regional sites with 29·6% recorded as positive. Regional metastasis occurred in 45 cases following a negative SLNB, for a false negative rate of 17·1%. Adjuvant regional radiotherapy in the setting of a negative SLNB did not affect regional recurrence (P = 0·31), providing credence to emerging evidence that regional therapy can be safely omitted in the setting of a negative SLNB. Distant relapse was noted far more frequently following a positive rather than negative SLNB (17·6% vs. 7·3%, P < 0·001).

Merkel cell carcinoma: An algorithm for multidisciplinary management and decision-making

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Therapeutic approach is often unclear, and considerable controversy exists regarding MCC pathogenesis and optimal management. Due to its rising incidence and poor prognosis, it is imperative to establish the optimal therapy for both the tumor and the lymph node basin, and for treatment to include sentinel node biopsy. Sentinel node biopsy is currently the most consistent predictor of survival for MCC patients, although there are conflicting views and a lack of awareness regarding node management. Tumor and node management involve different specialists, and their respective decisions and interventions are interrelated. No effective systemic treatment has been made available to date, and therefore patients continue to experience distant failure, often without local failure. This review aims to improve multidisciplinary decision-making by presenting scientific evidence of the contributions of each team member implicated in MCC management. Following this review of previously published research, the authors conclude that multidisciplinary team management is beneficial for care, and propose a multidisciplinary decision algorithm for managing this tumor.

Dramatic Increase in the Incidence and Mortality from Merkel Cell Carcinoma in the United States

Merkel cell carcinoma is a cutaneous neuroendocrine neoplasm that has been poorly studied in contemporary cohorts. Patients with Merkel cell carcinoma from 1986 to 2011 were identified in the Surveillance Epidemiology and End Results registry. A total of 5211 patients met the inclusion criteria. The mean age was 74.9 years; majority were male (61.4%) and white (94.9%). Patients were divided into two cohorts: Group 1 (1986 and 1999) and Group 2 (1999-2010). Group 2 was more likely to have Stage III disease (14.6 vs 23.3%, P < 0.001) and less likely to have Stage I/II disease (71.8 vs 65.1%, P < 0.0001). The increase in Stage III was likely secondary to increased use of sentinel lymph node biopsy. Disease-specific five-year survival for Stages I/II was 78.1 per cent and Stage III was 54 per cent. Disease-specific five-year survival was unchanged between Groups 1 and 2, 69.9 versus 66.6 per cent, respectively (P = 0.44). Both incidence and mortality significantly increased over the study period with P value for both trends <0.0001. In 1986, incidence and mortality rates per 100,000 were 0.22 and 0.03, respectively, and increased to 0.79 and 0.43 in 2011, respectively. There has been a greater than 333 per cent increase in mortality from Merkel cell carcinoma.