Management Recommendations for Merkel Cell Carcinoma—A Danish Perspective

Abstract

Merkel cell carcinoma (MCC) is a rare malignant neuroendocrine carcinoma of the skin with a poor prognosis and an apparent increase in incidence. Due to its rarity, evidence-based guidelines are limited, and there is a lack of awareness among clinicians. This review constitutes the consensus management recommendations developed by the Danish MCC expert group and is based on a systematic literature search. Patients with localized disease are recommended surgical excision and adjuvant radiotherapy to the primary site; however, this may be omitted in patients with MCC with low risk features. Patients with regional lymph node involvement are recommended complete lymph node removal and adjuvant radiotherapy in case of extracapsular disease. Metastatic disease was traditionally treated with chemotherapy, however, recent clinical trials with immune therapy have been promising. Immune checkpoint inhibitors targeting the programmed cell death protein 1(PD-1)/programmed death-ligand 1(PD-L1) axis should therefore be strongly considered as first-line treatment for fit patients. A 5-year follow-up period is recommended involving clinical exam every 3 months for 2 years and every 6 months for the following 3 years and PET-CT one to two times a year or if clinically indicated. These national recommendations are intended to offer uniform patient treatment and hopefully improve prognosis.

Merkel Cell Carcinoma: New Trends

“…Confirmative data are provided by a literature review on the role of FDG-PET-CT [ 37 ]. In addition, or as an alternative to PET-CT, ultrasound with fine needle cytology can be considered for the evaluation of regional lymph nodes [ 38 , 39 ].…”

“…However, guidelines and reviews concur that the preferred diagnostic method for assessment of lymph node status is sentinel lymph node biopsy (SLNB) [ 18 , 35 , 37 , 38 , 39 , 40 ]. In 25–45% of patients clinically staged N0, SLNB demonstrated lymph node metastases with the majority of studies indicating a number close to 30% [ 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”

“…Radical excision is generally considered the treatment of choice [ 35 , 38 , 39 ]. Wide resection margins, varying between 1 cm and 3 cm depending on localization, are recommended.…”

“…The target volume for radiotherapy includes the primary tumor bed after excision with a margin for microscopic spread. The Danish guideline recommends margins of 1–2 cm, but this is not evidence-based [ 39 ]. Expert opinion is that margins should be generous, up to 3 cm, but adjusted to critical structures and sensitive organs, especially in the face.…”

Avelumab for the treatment of patients with Merkel cell carcinoma

“…Использование авелумаба в дозе 10 мг/кг каждые 2 недели внутривенно капельно до прогрессирования заболевания или непереносимой токсичности при лечении пациентов с неоперабельной и/или метастатической карциномой Меркеля является новым стандартом терапии 6 на сегодняшний день [23,24]…”