Sentinel lymph node biopsy in clinically node‐negative Merkel cell carcinoma: the Westmead Hospital experience

Abstract

Background: Merkel cell carcinoma (MCC) is a rare, aggressive cutaneous malignancy with a propensity to metastasize to regional lymph nodes. Sentinel lymph node biopsy (SLNB) in patients with clinically node-negative MCC has been utilized to identify patients with subclinical nodal metastases. This study aims to review the accuracy of SLNB in MCC and to evaluate the impact of SLNB on management. Methods: Patients with clinically node-negative MCC who underwent SLNB were identified from a prospective database of patients treated at the Westmead Hospital, Sydney, between 1998 and 2017. Data from these patients were reviewed and analysed. Results: Forty-one patients were identified: 28 men and 13 women, median age 70 years. Median duration of follow-up was 27 months. Sixteen (39%) patients had a positive SLNB and all underwent nodal treatment which consisted of radiotherapy (n = 13), completion lymphadenectomy and adjuvant radiotherapy (n = 2), and completion lymphadenectomy alone (n = 1). Following negative SLNB, 24 of 25 patients did not undergo further nodal treatment. The false-negative rate was 16% as three patients developed in-field nodal recurrence subsequent to a negative SLNB. At last follow-up, 29 patients had no evidence of disease, six were alive with disease and three had died from other causes. Three SLN-positive patients have died of MCC. Conclusion: SLNB has a high rate of positivity and can improve the accuracy of staging and prognostication in MCC, and guide management. The relatively low risk of a falsenegative SLNB justifies close observation in SLNB-negative patients.

Should Sentinel Lymph Node Biopsy Status Guide Adjuvant Radiation Therapy in Patients With Merkel Cell Carcinoma?

“…12 In the absence of prospective data, reports have suggested that RT to the draining lymph node basin can be omitted for SLNB-negative patients, citing a low risk of regional recurrence. 3,[5][6][7] However, in these retrospective studies, regional relapse rates for these patients were 11% to 17% with overall relapse as high as 20% to 30%, and radiation fields were not uniform. 9 In this context, the over-riding goal of our study was to evaluate the low risk of regional recurrence when only the primary site was irradiated after a negative SLNB.…”

“…Some studies suggest adjuvant nodal RT can be safely omitted in SLNB-negative disease, citing low rates of regional recurrence. 3,[5][6][7] However, other studies demonstrate regional recurrence rates as high as 33% even in SLNB-negative patients, raising concern about the draining lymph nodes in this population. 22 Here, we report a 20-year experience treating MCC with adjuvant RT according to a policy of excluding the draining nodal basin for SLNB-negative MCC and including the draining nodal basin for SLNB-positive MCC.…”

S2k‐Leitlinie – Merkelzellkarzinom – Update 2022

“…Für Patienten mit Primärtumoren mit einem Durchmesser < 2 cm liegt das Fünfjahresüberleben bei 63–75%, für Primärtumoren mit einem Durchmesser > 2 cm bei 35–60%, für Patienten mit Lymphknotenmetastasen 27–52%, und für Patienten mit Fernmetastasen zwischen 13–18% 2,15,17–20 . Daher ist es nicht überraschend, dass Tumorbefall des Schildwächterlymphknotens ein wesentlicher prognostischer Parameter ist, der mit einer deutlich schlechteren Prognose einhergeht; da umgekehrt ein tumorfreier Schildwächterlymphknoten mit einer besseren Prognose assoziiert ist, werden Patienten mit nicht durch Schildwächterlymphknotenbiopsie gesicherten Lymphknotenstatus in der aktuellen Stadieneinteilung der AJCC einer intermediären Risikogruppe zugeordnet 21,22 . Zusätzlich wird der Anzahl an befallen Lymphknoten beziehungsweise dem Lymphknoten‐Ratio (lymph node ratio; LNR: Anteil positiver an untersuchten Lymphknoten) eine prognostische Bedeutung zugeschrieben.…”

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

“…However, SLNBs have been shown to be the most efficacious in the staging and prognostication, rather than the treatment, of MCC. Clinically node‐negative MCCs may demonstrate nodal positivity in SLNB assessment in as high as 48% of MCC cases 7,9 . On the other hand, SLNBs have been found to have a false‐negative rate of 16% 9 .…”

“…Clinically node‐negative MCCs may demonstrate nodal positivity in SLNB assessment in as high as 48% of MCC cases 7,9 . On the other hand, SLNBs have been found to have a false‐negative rate of 16% 9 . Patients that undergo SLNBs have been shown to have an increased 5‐year survival MCC‐specific survival rate compared to observation groups (79.2% vs. 73.8%; P = 0.004), but this outcome can also be attributed to the fact that patients receiving SLNB are younger, are more likely to receive radiotherapy, and have early stage tumors, thus, the independent benefit of SLNB on survival could not be fully ascertained 10 …”