A. C. Gasior1, A. Gingrich1, S. Deas1, J. Mammen1 1University Of Kansas,Surgery,Kansas City, KS, USA
Introduction:
Merkel cell cancer (MCC) is a rare and aggressive cutaneous neuroendocrine neoplasm. Sentinel lymph node biopsy (SLNB) is often used to assess for nodal metastases in breast cancer and melanoma, but the accuracy of SLNB for MCC is less well described with false negative rates varying from 0 to 50% (most studies based on administrative databases without consistent follow-up). In this study, we evaluated a single institution retrospective database of patients diagnosed with MCC to establish the accuracy of SLNB.
Methods:
After IRB approval, a single institution database was created spanning from January 2007 through December 2013. Patients had the standard SLNB technique of dual tracer evaluation (vital blue dye and radiolabelled sulfur colloid.) Patients were scheduled for surveillance every 6 months after surgery. Descriptive and chi-square analysis were used for statistical evaluation.
Results:
Of our 17 patients, the majority (64.7%) were male and over 66 years of age (52.9%). 15 patients (88.2%) had SLNB. The mean number of lymph nodes removed for sentinel lymph node biopsy was 2.6. 13/15 (86.7%) of SLNB were negative. Neither age, cancer site, nor size were independent predictors of nodal positivity. Of the 2 patients with positive SLNBs, only one patient had non-sentinel nodes (3/15) positive on subsequent lymphadenectomy. Of patients with negative SLNBs, there was no evidence of lymph basin only recurrence at follow-up in any patients (false negative rate of 0%). Median length of follow-up was 12 months.
Conclusion:
Previous MCC studies show extent of disease at presentation to be the greatest factor predictive of survival. In our study of early clinical stage MCC, patient factors were not identified to predict pathologic nodal involvement. In one of the largest series of patients with MCC evaluated with SLNB, the false negative rate was identified to be 0% suggesting that SLNB is an accurate technique to stage MCC patients for nodal metastases.