Merkel cell carcinoma of the head and neck: is adjuvant radiotherapy necessary?

Unlocking the Radiosensitizing Potential of MYC Inhibition in Neuroendocrine Malignancies

The MYC family of transcription factors-comprising c-MYC, N-MYC, and L-MYC-plays a pivotal role in oncogenesis, driving cancer progression and resistance to therapy. While MYC proteins have long been considered challenging drug targets due to their intricate structures, recent advances have led to the development of promising inhibitors. This review explores the role of MYC overexpression in promoting radiation therapy resistance in aggressive neuroendocrine malignancies through multiple mechanisms, including increased tumor cell invasion, enhanced DNA damage repair and oxidative stress management, prosurvival autophagy, survival of circulating tumor cells, angiogenesis, awakening from dormancy, and modulation of chronic inflammation and host immunity. Paradoxically, MYC overexpression can also enhance radiosensitivity in certain cancer cells by driving proapoptotic pathways, such as reactive oxygen species-induced DNA damage that overwhelms cellular repair mechanisms, ultimately leading to cell death. Additionally, we provide a comprehensive summary of direct MYC inhibitors, detailing their current stage of preclinical and clinical development as novel anticancer therapeutics. This review highlights the role of MYC in cancer metastasis and radiation therapy resistance while examining the potential of MYC inhibitors as radiosensitizers in adult and pediatric neuroendocrine malignancies, including small cell lung cancer, large cell neuroendocrine lung cancer, Merkel cell carcinoma, neuroendocrine-differentiated prostate cancer, neuroblastoma, central nervous system embryonal tumors, and medulloblastoma.

Postoperative Radiation Therapy Is Indicated for "Low-Risk" Pathologic Stage I Merkel Cell Carcinoma of the Head and Neck Region but Not for Other Locations

Purpose

The role of postoperative radiation therapy (PORT) in early stage Merkel cell carcinoma (MCC) is controversial. We analyzed the role of PORT in preventing local recurrences (LR) among patients with low-risk, pathologic stage I MCC based on the location of the primary tumors: head/neck (HN) versus non-HN sites.

Methods and Materials

One hundred forty-seven patients with MCC were identified that had "low risk" disease (pathologic T1 primary tumor, negative microscopic margins, negative pathologic node status, no immunosuppression or prior systemic therapy). LR was defined as tumor recurrence within 2 cm of the primary surgical bed, and its frequency was estimated with the cumulative incidence method.

Results

Seventy-nine patients received PORT (30 HN, 49 non-HN) with a median dose of 50 Gy (range, 8-64 Gy) and 68 patients were treated with surgery alone (30 HN, 38 non-HN). Overall, PORT was associated with a decreased risk of LR (5-year rate: 0% vs 9.5%; P = .004) with 6 LRs observed in the surgery alone group. Although the addition of PORT significantly reduced LR rates among patients with HN MCC (0% vs. 21%; P = .034), no LRs were observed in patients with non-HN MCC managed with surgery alone. There was no significant difference in MCC-specific survival comparing HN versus non-HN groups, with or without PORT.

Conclusions

For low-risk, pathologic stage I MCC of the extremities and trunk, excellent local control rates were achieved with surgery, and PORT is not indicated. However, PORT was associated with a significant reduction in LRs among low-risk MCC of the HN.

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

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

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.

Merkel cell carcinoma of the head and neck in the south-east of England

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine malignancy of the skin. Its incidence is increasing with half of cases involving the head and neck. To the best of our knowledge, few large studies have been published in the UK, and to date this is the largest reported series of head and neck MCC. We retrospectively reviewed the outcomes of patients with MCC in three hospitals in the south-east of England over a 12-year period (2008-2019). Diagnosis was based on histological data following biopsy. Overall survival and disease-specific survival were calculated using Kaplan-Meier and log-rank tests. Fifty-eight patients met the inclusion criteria (24 stage I, 22 stage II, 9 stage III, and 3 unclassified). Median disease-free survival was 36 months (95% CI 0 to 77.2) and median overall survival 50 months (95% CI 29.9 to 70). Overall five-year survival was 34.4% (95% CI 17% to 52%) with two-year survival at 62% (95% CI 48% to 76%). Five-year disease-free survival was 26.7% (95% CI 17 to 52%) with two-year disease-free survival at 54% (95% CI 40% to 68%). To date, this is the largest UK based study reporting overall and disease-free survival associated with MCC of the head and neck. Half the patients presented late, and surgery was the mainstay of treatment, augmented by adjuvant radiotherapy. There is a need to better stratify patients at risk of developing metastatic disease, with the use of sentinel lymph node biopsy and positron-emission tomography-computed tomography (PET-CT), as immunotherapy and targeted agents are now available to treat advanced disease.

The role of radiation therapy in the management of cutaneous malignancies. Part II: When is radiation therapy indicated?

Radiation therapy may be performed for a variety of cutaneous malignancies, depending on patient health status, tumor clinical and histologic features, patient preference, and resource availability. Dermatologists should be able to recognize the clinical scenarios in which radiation therapy is appropriate, as this may reduce morbidity, decrease risk of disease recurrence, and improve quality of life. The second article in this 2-part continuing medical education series focuses on the most common indications for radiation therapy in the treatment of basal cell carcinoma, cutaneous squamous cell carcinoma, dermatofibrosarcoma protuberans, Merkel cell carcinoma, Kaposi sarcoma, angiosarcoma, cutaneous lymphoma, melanoma, undifferentiated pleomorphic sarcoma, and sebaceous carcinoma.

The changing paradigm of managing Merkel cell carcinoma in Australia: An expert commentary

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine tumor of the skin with an estimated disease-associated mortality of 15-33%. Australia has a higher incidence of MCC compared to the rest of the world, thought to be due to a higher ultraviolet index. The Australian MCC population is distinct from the MCC population of the Northern hemisphere, characterized by a predominantly viral negative etiology with high tumor mutational burden. The optimal management of MCC and the choice of treatment modality vary significantly across the world and even between institutions within Australia. Historically, the treatment for MCC has been resection followed by radiotherapy (RT), though definitive RT is an alternative treatment used commonly in Australia. The arrival of immune checkpoint inhibitors and the mounting evidence that MCC is a highly immunogenic disease is transforming the treatment landscape for MCC. Australia is playing a key role in the further development of treatment options for MCC with two upcoming Australian/New Zealand investigator-initiated clinical trials that will explore the interplay of RT and immunotherapy in the treatment of early and late stage MCC.

[Personalized medicine in the treatment of periocular tumors : Targeted treatment and use of immune checkpoint inhibitors]

The aim of this article is to provide an overview on the current state of personalized medicine in the systemic treatment of selected periocular tumors, such as basal cell carcinoma, Merkel cell carcinoma and conjunctival melanoma. This article therefore provides an extensive current literature review from PubMed including the current guidelines and standard operating procedures (SOP). As 90% of basal cell carcinomas have a pathologic activation of the sonic hedgehog pathway, vismodegib is a new treatment option for inoperable or metastatic basal cell carcinoma and for patients with Gorlin-Goltz syndrome. A novel approach of systemic medicine for the treatment of metastatic Merkel cell carcinoma is immunotherapy using the immune checkpoint inhibitor avelumab. Other personalized immunotherapies, such as the checkpoint inhibitors pembrolizumab and nivolumab, the tyrosine kinase inhibitor pazopanib and the role of the hedgehog pathway in Merkel cell carcinomas are the subject of current research and will certainly play an important role in future treatment. In the narrow sense personalized medicine has only come true for metastatic conjunctival melanomas: systemic treatment with BRAF, MEK and/or checkpoint inhibitors is initiated only when a BRAF mutation is detected in the tumor or metastatic tissue. Systemic immunotherapy with the checkpoint inhibitors pembrolizumab and nivolumab can also be used as a treatment option in metastatic conjunctival melanomas. In summary, personalized medicine is a subject of current research and provides many new targeted treatment options especially for periocular malignancies; however, it also involves many great challenges in the development and implementation of new techniques and therapies.

Management of regional metastatic disease in cutaneous malignancy of the head and neck. 3. Merkel cell carcinoma

This is the third of three articles that give an overview of the current evidence for management of the neck and parotid in patients with cutaneous cancers of the head and neck. In this paper we discuss Merkel cell carcinoma (MCC) and review the latest evidence for management of the regional nodes.

Survival Impact of Time to Initiation of Adjuvant Radiation for Merkel Cell Carcinoma: An Analysis of the National Cancer Database

PURPOSE

This study aimed to determine the impact of time to initiation (TTI) of adjuvant radiation therapy (RT) on overall survival (OS) for patients with stage I or II Merkel cell carcinoma (MCC).

METHODS AND MATERIALS

The National Cancer Database was queried for patients with MCC of the head and neck, trunk, or extremities diagnosed between 2006 and 2014. Patients who did not undergo resection or receive adjuvant RT within 180 days of surgery were excluded. TTI was defined as the time from resection to first RT fraction. Linear regression was used to define factors associated with TTI. Recursive partitioning analysis modeling was performed to determine an optimal threshold for TTI. Cox proportional hazards modeling was performed to define covariates associated with OS.

RESULTS

A total of 2293 patients were included in this study. The median TTI for the cohort was 62 days (interquartile range, 43-86 days). TTI was not associated with OS for the overall cohort by multivariable Cox modeling (P = .19). Age, treatment facility type, lymph node examination, anatomic subsite, and surgical margin were associated with TTI (P < .05). Age, sex, insurance status, Charlson-Deyo comorbidity score, lymph node examination status, tumor size, and surgical margin were associated with OS (all P < .05).

CONCLUSIONS

Increased TTI of adjuvant RT was not associated with OS for patients with early stage MCC in this analysis of the National Cancer Database. The median TTI of 62 days from resection to adjuvant RT initiation for our study cohort contextualizes TTI on a national level and may offer reassurance for patients with prolonged postoperative wound healing or intercurrent illness delaying immediate RT initiation. Despite the lack of a clear detriment to survival with increased TTI up to 180 days from surgery, unnecessary delays in initiating adjuvant therapy should continue to be minimized while ensuring optimal recovery from resection.

Merkel cell carcinoma of the eyelid: A review

Merkel cell carcinoma (MCC) is a rare, aggressive tumor of both epithelial and neuroendocrine origin, which carries a mortality rate of up to 40%. MCC tumors typically present as painless, expanding nodules on the sun-exposed skin areas of older, white patients. Eyelid and periocular tumors comprise approximately 2.5% of all cases of MCC and may be mistaken for chalazia or basal cell carcinomas. Immunosuppression is a significant risk factor, particularly in solid-organ-transplant recipients, patients with chronic lymphocytic leukemia, and patients with HIV. Sentinel lymph node biopsy is often used for accurate staging of head and neck MCC. Treatment includes wide local excision, commonly with the addition of radiotherapy for improved locoregional disease control. Historically, adjuvant chemotherapy had been reserved for metastatic disease, but immunotherapy and targeted chemotherapies are currently being investigated for use in primary disease. The clinical characteristics of all available published cases of eyelid MCC are summarized in this article.

Demographics and outcomes of stage I and II Merkel cell carcinoma treated with Mohs micrographic surgery compared with wide local excision in the National Cancer Database

BACKGROUND

The optimal surgical approach (wide local excision [WLE] vs Mohs micrographic surgery [MMS]) for treating Merkel cell carcinoma (MCC) is yet to be determined.

OBJECTIVE

To compare survival outcomes in patients with early-stage MCC treated with MMS versus with WLE.

METHODS

A retrospective review of all cases in the National Cancer Database (NCDB) of MCC of clinical stage I or II MCC treated with WLE or MMS was performed.

RESULTS

A total of 1795 cases of stage I or II MCC who underwent WLE (n = 1685) or MMS (n = 110) were identified. There was no difference in residual tumor on surgical margins between the 2 treatment groups (P = .588). On multivariate analysis, there was no difference in overall survival between the treatment modalities (adjusted hazard ratio, 1.02; 95% confidence interval, 0.72-1.45; P = .897). There was no difference in overall survival between the 2 groups on propensity score-matched analysis.

LIMITATIONS

Disease-specific survival was not reported, as these data are not available in the National Cancer Database.

CONCLUSIONS

MMS appears to be as effective as WLE in treating early-stage MCC.

Management of cutaneous Merkel cell carcinoma

PURPOSE

To report the outcomes of patients with previously untreated cutaneous Merkel cell carcinoma (MCC) managed with curative intent.

MATERIAL AND METHODS

Between December 1984 and August 2015, 59 patients with previously untreated cutaneous MCC were managed with curative intent with surgery and adjuvant radiotherapy (54 patients) or radiotherapy alone (5 patients) at the University of Florida. Primary sites included head and neck (45 patients), extremities (11 patients) and trunk (3 patients). Adjuvant chemotherapy was employed in 14 patients. Patients were staged according to the AJCC staging system: stage I, 25 patients; stage IIA, 7 patients; and, stage III, 27 patients. No patients had distant metastases. Median follow-up for all patients was 3.2 years (range, 0.3-20.9 years). Median follow-up for survivors was 6.7 years (range, 1.6-20.9 years).

RESULTS

The 5-year outcomes were as follows: local control, 91%; regional control, 79%; local-regional control, 77%; disease metastasis-free survival, 60%; cause-specific survival, 53%; and overall survival, 39%. The 5-year outcomes for patients with stage I-IIA versus stage-III disease were the following: local-regional control, 90% versus 57% (p = .0115); distant metastasis-free survival, 78% versus 36% (p = .0002); cause-specific survival, 68% versus 35% (p = .0050); and overall survival, 48% versus 27% (p = .0377). Local-regional recurrences occurred in 12 patients; no patients were successfully salvaged. Severe late complications were observed in four patients.

CONCLUSIONS

Although radiotherapy alone or combined with surgery results in a relatively high likelihood of local-regional control, the majority of recurrences are distant and approximately half of patients are cured. Patients with regional disease at diagnosis have significantly worse outcomes.

Adjuvant radiation therapy improves patient survival in early-stage merkel cell carcinoma: A 15-year single-institution study

OBJECTIVES/HYPOTHESIS

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine neoplasm of the skin. Growing evidence supports the benefit of postoperative adjuvant radiation therapy (RT) for locoregional control, but whether it improves overall survival (OS) has been debated. Our objective was to compare the OS of MCC patients who received postoperative RT with those who received surgery alone.

STUDY DESIGN

Retrospective case series.

METHODS

Cases of MCC between 2001 and 2016 at the University of California, Los Angeles Health System were reviewed. We identified 87 unique cases of MCC. Among the patients, 74% were identified as male and 26% as female. The average age at diagnosis was 71.2 years. The median survival was 48.0 months. The OS of all the patients at 2 years, 5 years, and 10 years was 54%, 46%, and 26%, respectively. Univariate analysis showed that stage, T stage, N stage, and M stage were significant determinants of OS. The inclusion of RT was not found to be a determinant; however, when restricting the analysis to early-stage MCC (stages I and II), postoperative adjuvant RT was associated with significantly improved OS. A Cox regression model confirmed that inclusion of RT was an independent prognosticator of OS even when controlled for overall stage and negative margin status. The small sample size and retrospective nature of this study limit its statistical power.

CONCLUSIONS

MCC is an aggressive tumor with a poor prognosis for survival especially in elderly patients. In this study, we found that RT during early-stage MCC improves OS. Prospective randomized control trials are necessary to validate the observed benefit for MCC patients.

LEVEL OF EVIDENCE

4 Laryngoscope, 1862-1866, 2018.

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.

Identifying an Optimal Adjuvant Radiotherapy Dose for Extremity and Trunk Merkel Cell Carcinoma Following Resection: An Analysis of the National Cancer Database

Importance

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine neoplasm with a high risk of recurrence following resection. Despite a rising incidence over the past 3 decades, there is a paucity of prospective data owing to the rarity of this disease.

Objective

To determine the optimal adjuvant radiation therapy (RT) dose following resection of localized MCC of the extremities or trunk.

Design, Setting, and Participants

Using the National Cancer Database, a large national database consisting of a heterogeneous population and treatment settings, we retrospectively analyzed a cohort of 2093 patients 18 years or older with stage I to III MCC of the extremities and/or trunk treated with definitive surgery and adjuvant RT between 1998 and 2011. Exclusion criteria included receiving treatment with palliative intent, preoperative RT, non-external-beam RT, and radiation dose of 30 Gy or lower or 70 Gy or higher. Cox proportional hazards regression model was used to compare overall survival (OS) between RT dose groups, accounting for age, sex, race, stage, surgery type, margin status, comorbidities, and use of chemotherapy.

Exposures

Radiation therapy dose was categorized into 4 groups: group 1 received the lowest dose (>30 to <40 Gy); group 2, the next lowest (40 to <50 Gy); group 3, the second highest dose (50 to 55 Gy); and group 4, the highest dose (>55 to 70 Gy).

Main Outcome and Measure

Overall survival.

Results

Data from 2093 patients were analyzed; there were 1293 men (61.8%) and 800 women (38.2%) (median age, 73 years). After a median follow-up of 37 months for the entire cohort, 904 deaths were reported. The 3-year OS rates for groups 1, 2, 3, and 4 were 41.8%, 69%, 69.2%, and 66%, respectively (omnibus P < .001). Compared with group 3 (50 to 55 Gy), equivalent OS was seen in group 2 (40 to <50 Gy; adjusted hazard ratio [AHR], 0.89; 95% CI, 0.63-1.27; P = .52) and group 4 (>55 to 70 Gy; AHR, 1.18; 95% CI, 0.93-1.48; P = .17), but worse OS was found in group 1 (>30 to <40 Gy; AHR, 2.63; 95% CI, 1.44-4.80; P < .001).

Conclusions and Relevance

Adjuvant RT dose from 40 to lower than 50 Gy appears adequate for extremities and/or trunk stage I to III MCC, with OS equivalent to that found at higher-dose regimens (>50 to 70 Gy).

Impact of total radiotherapy dose on survival for head and neck Merkel cell carcinoma after resection

BACKGROUND

Head and neck Merkel cell carcinoma (MCC) is commonly treated with surgery and adjuvant radiotherapy (RT) for high-risk features. The optimal radiation dose is unknown.

METHODS

One thousand six hundred twenty-five eligible patients with head and neck MCC were identified in the National Cancer Data Base (NCDB). Radiation dose was divided into 3 groups: 30 to <50 Gray (Gy), 50-55 Gy, and >55-70 Gy. Cox regression was used to compare overall survival (OS) between groups, accounting for age, sex, stage, surgery type, margin status, comorbidities, and use of chemotherapy.

RESULTS

With a median follow-up of 33.5 months, 3-year OS was 48.9%, 70.3%, and 58.7% for 30 to <50 Gy, 50-55 Gy, and >55-70 Gy, respectively (P < .001). Compared to 50-55 Gy, doses between 30 to <50 Gy (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI] 1.17-1.99; P = .002) and >55-70 Gy (adjusted HR 1.21; 95% CI 1.0-1.46; P = .06) were associated with worse survival.

CONCLUSION

Adjuvant radiation doses within 50-55 Gy may be optimal for head and neck MCC.

Systematic literature review of efficacy, safety and tolerability outcomes of chemotherapy regimens in patients with metastatic Merkel cell carcinoma

AIM

Merkel cell carcinoma (MCC) is a rare neuroendocrine, cutaneous malignancy with poor prognosis once metastasized. The aim of this study was to conduct a systematic literature review to assess clinical outcomes associated with chemotherapy regimens in metastatic MCC.

MATERIALS & METHODS

Embase^®, MEDLINE^®, MEDLINE^®-In-Process and CENTRAL were searched for studies published in January 2016.

RESULTS & CONCLUSION

Overall, the literature on chemotherapy in patients with metastatic MCC is sparse, with most studies being case series/reports. Across all studies, response rates ranged from 20 to 61%, with higher response rates in first-line setting (53-61%) versus second-line setting (23-45%). Among responders, duration of response was short (≤8 months) in both first- and second-line settings. There is a need for novel agents that can induce durable responses in metastatic MCC.

[Care of Merkel cell carcinoma and role of the radiotherapy]

Merkel cell carcinoma is a rare neuro-endocrine tumor of skin with a poor prognosis. Data available in literature are scarce. Current treatment for locoregional disease is based on combined treatment by surgery and radiotherapy. However these treatments are controversial. The aim of the present review is to sum up the different available studies and to compare national and international guidelines.

Merkel cell carcinoma: Epidemiology, prognosis, therapy and unmet medical needs

Merkel cell carcinoma (MCC) is a rare skin cancer that is associated with Merkel cell polyomavirus infection in most cases. Incidence rates of MCC have increased in past decades. Risk factors for MCC include ultraviolet light exposure, immunosuppression and advanced age. MCC is an aggressive malignancy with frequent recurrences and a high mortality rate, although patient outcomes are generally more favourable if the patient is referred for treatment at an early stage. Although advances have been made recently in the MCC field, large gaps remain with regard to definitive biomarkers and prognostic indicators. Although MCC is chemosensitive, responses in advanced stages are mostly of short duration, and the associated clinical benefit on overall survival is unclear. Recent nonrandomised phase 2 clinical trials with anti-PD-L1/PD-1 antibodies have demonstrated safety and efficacy; however, there are still no approved treatments for patients with metastatic MCC. Patients with advanced disease are encouraged to participate in clinical trials for treatment, indicating the largely unmet need for durable, safe treatment within this population.

Merkel Cell Carcinoma: An Update of Key Imaging Techniques, Prognostic Factors, Treatment, and Follow-up

Merkel cell carcinoma, though rare, is one of the most aggressive tumors a dermatologist faces. More than a third of patients with this diagnosis die from the disease. Numerous researchers have attempted to identify clinical and pathologic predictors to guide prognosis, but their studies have produced inconsistent results. Because the incidence of Merkel cell carcinoma is low and it appears in patients of advanced age, prospective studies have not been done and no clear treatment algorithm has been developed. This review aims to provide an exhaustive, up-to-date account of Merkel cell carcinoma for the dermatologist. We describe prognostic factors and the imaging techniques that are most appropriate for evaluating disease spread. We also discuss current debates on treating Merkel cell carcinoma.

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.

Radiotherapy and Conservative Surgery in the Locoregional Management of Merkel Cell Carcinoma: The British Columbia Cancer Agency Experience

BACKGROUND

Merkel cell carcinoma (MCC) is an uncommon aggressive skin malignancy. Published series mainly focus on wide excision, which can be difficult at some sites (e.g., face) and in patients with comorbidities. In British Columbia, an approach of conservative surgery followed by radiotherapy is common.

MATERIALS AND METHODS

This is a retrospective review of 179 patients treated for MCC with curative intent in British Columbia.

RESULTS

Totals of 68, 63, and 37 patients underwent narrow excision of primary, attempted wide excision, and biopsy only, respectively. Adjuvant radiotherapy reduced local recurrence after narrow excision (<10 mm margin) from 25 to 4.9 % (p = .03) and was effective in the presence of microscopic positive margins. Local recurrence rate was 7.1 % if the margin was >10 mm irrespective of radiation use. Local RFS was improved by adjuvant radiation therapy (RT) (p = 0.04), and there was a trend to reduced nodal relapse after elective nodal RT (p = .07). Irradiation of macroscopic tumor at 37 primary and 33 nodal sites provided 5-year local and nodal RFS of 90 and 75 %, respectively. The 5-year cancer specific survival was 77 % and was not improved by the use of adjuvant radiotherapy.

CONCLUSIONS

Local excision plus adjuvant RT is an effective treatment for MCC. Adjuvant radiation should be considered when the excision margin is <1 cm.

A systematic review of patients with Merkel cell carcinoma of the head and neck and a negative sentinel lymph node biopsy

Background

A negative sentinel lymph node biopsy (SLNB) from patients with head and neck Merkel cell carcinoma (HNMCC) may allow the patient to avoid further adjunctive therapies. However, there is considerable regional variability of lymphatic drainage from primary sites involving the head and neck, and Merkel cell carcinoma (MCC) has aggressive biologic behavior.

Objective

The primary aim of this systematic review was to document the incidence of regional recurrence and mortality from HNMCC patients after a negative SLNB.

Methods

A systematic search of the English literature was conducted via Ovid Medline and Embase from inception until 2013 and the Cochrane Central Register of Controlled Trials from 1991 to January 2014.

Results

Twenty-three studies, with a total of 81 patients matched the inclusion criteria. The incidence of regional recurrence from the entire cohort was 12.3%, and there was a 5% mortality rate. The mean follow-up time, excluding the 30 patients who did not have individual follow-up times specified, was 32.8 months.

Limitations

This review included studies had variable follow-up durations and treatments for MCC.

Conclusions

Despite negative pathologic staging of the neck using SLNB in HNMCC patients, there is still a high incidence of regional recurrence and mortality, over a short follow-up period.

•

Merkel cell carcinoma is an aggressive neoplasm.

•

Patients with a negative sentinel lymph node biopsy from head and neck Merkel cell carcinoma showed a high incidence of future regional lymph node involvement.

•

In this context, a negative sentinel lymph node biopsy is not necessarily reassuring for the patient or the clinician.

Treatment of Merkel cell carcinoma of the head and neck: a systematic review

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive neurocutaneous malignancy that frequently arises in sun-exposed areas of the head and neck. Standard therapy focuses on wide local excision (WLE) with adjuvant locoregional radiotherapy. However, treatment is often complicated by concerns for cosmesis and for preservation of the head and neck neurovasculature.

OBJECTIVE

To explore treatment-related outcomes of the head and neck MCC.

METHODS

A MEDLINE and Google Scholar search was performed for studies focusing on the head and neck MCC treatment.

RESULTS

The search terms produced 100 articles. Seventeen studies met eligibility/screening criteria, yielding 868 patients. Three of the 6 relevant studies found a significant difference in disease-free survival (DFS) between surgery and surgery plus adjuvant radiation. Two studies found no difference in DFS or overall survival (OS) in patients receiving chemotherapy. Two studies found no difference in DFS between radiotherapy and surgery with adjuvant radiation. No difference in OS was found between WLE and Mohs surgery.

CONCLUSION

In an uncomplicated head and neck MCC, treatment with surgery and adjuvant radiotherapy is effective in increasing survival and reducing recurrence. Radiotherapy alone may be appropriate for inoperable regions. Primary chemotherapy seems to have a limited role; however, few studies explored this treatment modality.

Management of early stage cutaneous Merkel cell carcinoma of the head and neck

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer of neuroendocrine origin. As a result, few large studies have been published, and we know of even fewer on disease of the head and neck alone. The most appropriate way to manage patients with early local disease and no sign of metastases neck is controversial. We reviewed management of early cutaneous MCC of the head and neck in 8 hospitals in the United Kingdom over 12 years between 1999 and 2011 (the largest head and neck series in Europe to date), and identified 39 patients (19 men and 20 women) with early disease according to a well recognised classification. A total of 24 patients had stage Ia disease, 11 had stage Ib disease, and 4 were unclassified. Five of those with stage Ia disease developed regional metastases and 7 with stage Ib disease developed regional recurrence. The 2-year overall survival for stage Ia and Ib disease was 62% and 27%, respectively. Our study shows that prognosis is poor after conservative surgical management of stage I disease. Management of the neck is still controversial, and a meta-analysis of all the published data is needed to establish best practice statistically.

Milestones in the staging, classification, and biology of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive skin cancer that is causally associated with ultraviolet light exposure and a recently discovered polyomavirus. Before 2010, MCC was staged using any of 5 unique systems in active use. In 2010, a consensus staging system for MCC was adopted worldwide and replaced these systems. This consensus system includes substages that reflect prognostic differences based on whether nodal evaluation was performed by pathologic analysis or clinical assessment alone. MCC-specific disease classification in ICD-9, to be expanded in the upcoming ICD-10, has improved the ability to track and manage this malignancy. Several biomarkers and histopathologic features have been identified that improve understanding of this cancer and may lead to future refinement of the current staging system. In 2008, the Merkel cell polyomavirus was discovered and is now thought to be a critical mechanism of transformation in at least 80% of MCCs. In patients who produce antibodies to the viral T-antigen oncoprotein, the titer increases and decreases with MCC disease burden and can be a clinically useful marker of recurrence. Diverse studies link CD8-positive T-cell function with outcomes in MCC and serve as the rational basis for ongoing trials of therapies to augment cellular immunity. This article reviews basic and translational research insights that will lead to improved staging, prognostic accuracy, and mechanism-based therapy for this often-lethal skin cancer.

Diagnosis and management of merkel cell carcinoma of the head and neck: current trends and controversies

Merkel cell carcinoma is an aggressive neuroendocrine cutaneous malignancy with a predilection for regional and distant metastasis. This malignancy presents most commonly on the head and neck of elderly Caucasian males, with a higher prevalence in the immunosuppressed. A high index of suspicion must be maintained due to the often asymptomatic presentation. Lip tumors, scalp tumors, local invasion, nodal metastasis, distant metastasis, and lymphovascular invasion are poor prognostic factors. Up to 8.7% of patients present with distant metastasis, and PET-CT is an accurate staging tool with a 90% sensitivity. Combined aggressive surgical resection with adjuvant radiotherapy affords the best regional control rates. The regional lymphatics must be addressed with either sentinel lymph node biopsy, surgery, or elective radiation due to the risk of occult metastasis. Addition of chemotherapy has no proven benefit in locoregional control.

Gene expression differences predict treatment outcome of merkel cell carcinoma patients

Due to the rarity of Merkel cell carcinoma (MCC), prospective clinical trials have not been practical. This study aimed to identify biomarkers with prognostic significance. While sixty-two patients were identified who were treated for MCC at our institution, only seventeen patients had adequate formalin-fixed paraffin-embedded archival tissue and followup to be included in the study. Patients were stratified into good, moderate, or poor prognosis. Laser capture microdissection was used to isolate tumor cells for subsequent RNA isolation and gene expression analysis with Affymetrix GeneChip Human Exon 1.0 ST arrays. Among the 191 genes demonstrating significant differential expression between prognostic groups, keratin 20 and neurofilament protein have previously been identified in studies of MCC and were significantly upregulated in tumors from patients with a poor prognosis. Immunohistochemistry further established that keratin 20 was overexpressed in the poor prognosis tumors. In addition, novel genes of interest such as phospholipase A2 group X, kinesin family member 3A, tumor protein D52, mucin 1, and KIT were upregulated in specimens from patients with poor prognosis. Our pilot study identified several gene expression differences which could be used in the future as prognostic biomarkers in MCC patients.

The role of postoperative radiation and chemoradiation in merkel cell carcinoma: a systematic review of the literature

OBJECTIVE

A systematic review of the literature was undertaken to investigate whether adjuvant radiotherapy and/or chemotherapeutics offered any additional benefit than surgery alone in the treatment of Merkel Cell Carcinoma (MCC).

METHODS

A PubMed, MEDLINE search was conducted between 1995 and 2013, to identify reported cases of surgically treated MCC followed by either observation, radiation, or chemoradiation. Patient demographics and outcomes were recorded and compared in a systematic fashion.

RESULTS

Thirty-four studies (n = 4475) were included. The median age was 73 years, median follow up was 36 months and there was a 1.5:1 ratio of men to women. All 4475 patients had surgery, 1975 had no further treatment, 1689 received postoperative RT, and 301 received postoperative chemoRT. The most common site was face/head/neck, 47.8%. Stage 1 was the most common clinical stage at diagnosis (57%). Three-year local control was 20% (median 10%) in the observation cohort, compared to 65% (62%) with postoperative RT, and 67% (75%) with postoperative chemoRT; these findings were statistically significant (P < 0.001). Recurrence was found to be 38% (60%) in the observation cohort, compared to 23% (20%) with postoperative RT (P < 0.001). Three-year overall survival (OS) was found to be 56% (57%) in the observation cohort, compared to 70% (78%) with postoperative RT and 73% (76%) with postoperative chemoRT (P < 0.001). The observation cohort had a median OS of 44 months compared with 64 months (P < 0.001) in the postoperative RT cohort. There was no statistically significant difference in any parameters assessed between postoperative radiation and postoperative chemoradiation arms.

CONCLUSION

The comprehensive collection of retrospective data suggests a survival and control benefit for postoperative radiation in MCC. No differences were noted between adjuvant radiation and chemoradiation. This analysis indicates the need for prospective trials with patients stratified by known prognostic factors.

Benefits of combined modality treatment of Merkel cell carcinoma of the head and neck: single institution experience

BACKGROUND

There is ongoing debate surrounding the roles of surgery and adjuvant radiotherapy in the management of primary and recurrent Merkel cell carcinoma of the head and neck. This study assessed the influence of local excision, margin status, adjuvant radiotherapy and chemotherapy on locoregional recurrence and survival.

METHOD

A retrospective review of 54 consecutive cases of head and neck Merkel cell carcinoma at a single institution.

RESULTS

Median disease-specific survival time was 120 months. Forty-four per cent of patients developed locoregional recurrence. Combined treatment with surgery and locoregional radiotherapy improved diseasespecific survival. Radiotherapy was associated with longer time to recurrence and regional recurrence. Irradiation of the regional nodes improved regional control, irrespective of clinical status. Margin-negative excision was not associated with improved local control. Combined modality treatment of recurrent disease resulted in a four-fold improvement of local control, but small numbers prevented this trend from reaching statistical significance.

CONCLUSION

Surgical excision of the primary disease and clinically involved regional nodes, plus adjuvant radiotherapy to the surgical bed and regional nodes are recommended for all patients with Merkel cell carcinoma of the head and neck, irrespective of clinical status. Recurrent disease should be aggressively treated with combined modality treatment.

Merkel cell carcinoma: what do we know about it and what should we do?

Merkel cell carcinoma (MCC) is a rare primary cutaneous carcinoma of the skin that is highly aggressive, and has a high risk of locoregional and distant spread, a mortality rate considerably higher than that of cutaneous melanoma and poor survival. Its incidence has increased during the past twenty years. The studies published since 2008 have introduced changes in the understanding of its epidemiology and pathogenesis, and consequently the therapeutic approach. Despite this, there is still controversy surrounding its optimal management, which requires clarification. This is the purpose of this review.

Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, clinically aggressive cutaneous neuroendocrine neoplasm with a high mortality rate. Though the etiology is not precisely known, Merkel cell polyomavirus DNA has been found recently in a large percentage of MCC tumors. Other suggested risk factors include sun exposure, immunosuppression, and a history of prior malignancy. Work up of patients with MCC most notably includes nodal staging via clinical examination or sentinel lymph node biopsy. The prognosis for most patients with MCC is poor, and the rarity of MCC precludes the prospective, randomized clinical trials necessary to elucidate optimum treatment protocols. Most published data support the use of a multimodality approach centered around surgical excision with negative margins, sentinel lymph node biopsy to establish the presence or absence of nodal metastases, adjuvant radiothearpy to decrease the risk of recurrence, and systemic chemotherapy in the case of widespread disease.

A practical update of surgical management of merkel cell carcinoma of the skin

The role of surgeons in the treatment of Merkel cell carcinoma (MCC) of the skin is reviewed, with respect to diagnosis and treatment. Most of the data in the literature are case reports. Surgery is the mainstay of treatment. A wide local excision, with sentinel node (SLN) biopsy, is the recommended treatment of choice. If SLN is involved, nodal dissection should be performed; unless patient is unfit, then regional radiotherapy can be given. Surgeons should always refer patients for assessment of the need for adjuvant treatments. Adjuvant radiotherapy is well tolerated and effective to minimize recurrence. Adjuvant chemotherapy may be considered for selected node-positive patients, as per National Comprehensive Cancer Network guideline. Data are insufficient to assess whether adjuvant chemotherapy improves survival. Recurrent disease should be treated by complete surgical resection if possible, followed by radiotherapy and possibly chemotherapy. Generally results of multimodality treatment for recurrent disease are better than lesser treatments. Future research should focus on newer chemotherapy and molecular targeted agents in the adjuvant setting and for gross disease.

Merkel cell carcinoma - description of five cases

Merkel cell carcinoma (MCC) is a rare but very aggressive skin cancer that derives from neuroendocrine cells of the skin. Merkel cell carcinoma morbidity has been continuously increasing for the last few years. Increasing reported incidence of MCC is probably connected with increasing occurrence of this kind of malignancy or with development of histological and immunohistochemical methods of sample examinations which have allowed for more precise diagnosis of skin tumor that might have previously not been accurately recognized. Merkel cell carcinoma develops as nodules early recognized as basocellular carcinoma, squamous cell carcinoma, amelanotic melanoma or skin lymphoma. Merkel cell carcinoma can be morphologically similar to skin metastasis as well as mild changes such as lipoma, cysts, fibroma or vessel changes. Accurate diagnosis is very important because it determines successful management and risk of progression of disease. We describe 5 patients with MCC who underwent surgical excision and then, after estimation of stage of disease, complementary treatment. Our observations prove that every tumor with MCC should be cut out with wide margins and regional lymphadenectomy or sentinel node biopsy is compulsory. After cutting out MCC involved-field radiotherapy is necessary and improves prognosis. Presence of metastases in lymphatic nodes is an indication for complementary chemotherapy.

Merkel cell carcinoma: 30-year experience from a single institution

BACKGROUND

Merkel cell carcinoma (MCC) is a rare cutaneous malignancy. Few single-institution series have been reported.

METHODS

Review of MCC patients treated at our institution between 1980 and 2010. Patient, tumor, and treatment variables were analyzed to determine MCC-specific outcomes.

RESULTS

We identified 161 patients with MCC. There was a 2.5-fold increase in cases over the last decade. Median length of follow-up was 36 months. Stage at diagnosis was I in 35 %, II in 21 %, IIIa in 12 %, IIIb in 23 %, and IV in 9 %. The 5-year MCC-specific survival rates were 87, 63, 42, and 0 % for stages I, II, III, and IV, respectively. Death from the disease occurred in 10 % of patients with T1 and in 50 % with larger lesions. One-third of patients presented with nodal disease. Sentinel lymph node biopsy (SLNB) identified micrometastases in 9 out of 27 (33 %) early-stage patients. Recurrence developed in 56 % of SLNB-positive and 39 % of SLNB-negative patients. Half of patients recurred after a median time of 9 months. Proportions of first recurrence location were distant (52 %), nodal (27 %), and local (21 %). Adjuvant treatments did not improve recurrence or survival rates. One-third of patients died of the disease.

CONCLUSIONS

SLNB identifies micrometastasis in one-third of early-stage patients. Negative SLNB may predict for improved but not necessarily favorable outcome. Initial tumor size and clinical nodal disease predict for poor outcome. High recurrence rates warrant the development of more effective adjuvant therapies, and better markers of recurrence and treatment response for MCC are needed.