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Study supports SLNB for all primary Merkel cell carcinoma

Regardless of size, all primary Merkel cell carcinoma displayed metastatic potential, suggesting the need for sentinel lymph node biopsy, according to study data.

In a multicenter, retrospective study, US researchers evaluated 240 patients (mean age at diagnosis, 70.1 years; 70% men; 74.2% Caucasian) with known primary Merkel cell carcinoma (MCC). Overall survival and survival free of locoregional recurrence were calculated, and researchers performed statistical analyses of characteristics and outcomes.

 

Jerry D. Brewer

“MCC is an aggressive form of skin cancer that can spread quickly and kill,” researcher Jerry D. Brewer, MD, a dermatologist at Mayo Clinic, Rochester, Minn., told Healio.com. “Any MCC regardless of how small initially should have a sentinel lymph node removed as part of the initial treatment approach.

“MCC … has been difficult to study due to the rarity of the tumor,” Brewer said. “We felt it would be beneficial to gather data on a large group of patients to confirm and expound on what is already known about this intriguing form of skin cancer.”

Tumors (mean size, 2.2 cm for all sites) were located primarily in the head and neck (46.3%). Seventy-five (31.3%) patients were stage I at diagnoses, 41 (17.1%) were stage II, 56 (23.3%) were stage III and five (2.1%) were stage IV. Remaining patients could not be staged based on criteria from the 2009 American Joint Committee on Cancer.

Compared with stage I patients, stage II patients had improved overall 3-year survival (87.8% vs. 74.4%) and greater overall survival (P=.023). Significantly worse survival was experienced by stage III patients compared with patients in stage I (HR=1.68; 95% CI, 1.02-2.73) and stage II (HR=3.45; 95% CI, 1.73-6.85).

Immunosuppressed patients (n=33) had an overall 3-year survival of 43.4% compared with 68.1% for immunocompetent patients (n=207). Nodal involvement was not predicted by primary tumor size.

“MCC in patients that are immunosuppressed should be taken very seriously, as MCC in this scenario has proven to behave more aggressively,” Brewer said. “In a recent study looking at MCC in patients with CLL [chronic lymphocytic leukemia], which is known to cause immunosuppression, patients were 3.8 times more likely to die from metastatic MCC than patients without CLL.”