Original article
Pathologic nodal evaluation improves prognostic accuracy in Merkel cell carcinoma: Analysis of 5823 cases as the basis of the first consensus staging system

This study was presented in part at the Second World Meeting of Melanoma Centers, Clearwater, Florida, November 22, 2008.
https://doi.org/10.1016/j.jaad.2010.02.056Get rights and content

Background

The management of Merkel cell carcinoma (MCC) has been complicated by a lack of detailed prognostic data and by the presence of conflicting staging systems.

Objective

We sought to determine the prognostic significance of tumor size, clinical versus pathologic nodal evaluation, and extent of disease at presentation and thereby derive the first consensus staging/prognostic system for MCC.

Methods

A total of 5823 prospectively enrolled MCC cases from the National Cancer Data Base had follow-up data (median 64 months) and were used for prognostic analyses.

Results

At 5 years, overall survival was 40% and relative survival (compared with age- and sex-matched population data) was 54%. Among all MCC cases, 66% presented with local, 27% with nodal, and 7% with distant metastatic disease. For cases presenting with local disease only, smaller tumor size was associated with better survival (stage I, ≤2 cm, 66% relative survival at 5 years; stage II, >2 cm, 51%; P < .0001). Patients with clinically local-only disease and pathologically proven negative nodes had better outcome (76% at 5 years) than those who only underwent clinical nodal evaluation (59%, P < .0001).

Limitations

The National Cancer Data Base does not capture disease-specific survival. Overall survival for patients with MCC was therefore used to calculate relative survival based on matched population data.

Conclusion

Although the majority (68%) of patients with MCC in this nationwide cohort did not undergo pathologic nodal evaluation, this procedure may be indicated in many cases as it improves prognostic accuracy and has important treatment implications for those found to have microscopic nodal involvement.

Section snippets

Methods

Cases from the NCDB were identified using MCC-specific histology code 8247. A flow diagram of the MCC cases used for the prognosis and staging analysis is shown in Fig 1. There were 10,020 patients with MCC captured in the NCDB between 1986 and 2004 who were used for basic demographic analyses (Table I). The NCDB policy is to collect follow-up data from the time of initial diagnosis at 5-year intervals. All patients given a diagnosis before the year 2000 (5823 patients) had follow-up data

Results

The clinical and demographic characteristics of 10,020 MCC cases captured by the NCDB are shown in Table I. Similar to smaller, previously reported cohorts,1, 5, 15, 16 men comprised the majority of cases (61%). The age at diagnosis was 50 years or older in 94% of MCC cases and the median age was 76 years. Head/neck presentation was the most common primary site (45%). Non-Caucasian ethnicities were underrepresented in the MCC cohort (4%) as compared with their representation in the US

Discussion

Here we present the prognostic analysis used to derive the first unified staging system for MCC. It is anticipated that this staging system, along with the recent introduction of 7 new MCC-specific diagnostic codes (International Classification of Diseases, Ninth Revision, Clinical Modification),21 will aid in standardizing language used to describe MCC and its prognosis among patients, clinicians, and researchers. This staging system is the result of multidisciplinary consensus meetings that

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    Dr Lemos is currently affiliated with the Department of Dermatology, Emory University, Atlanta, GA.

    Supported by National Institutes of Health (NIH) K02-AR50993; American Cancer Society (ACS) RSG-08-115-01-CCE; ACS Jerry Wachter Merkel Cell Carcinoma (MCC) Fund; NIH K24-CA139052; an unrestricted educational grant from Schering Pharmaceutical, Kenilworth, NJ; the David & Rosalind Bloom Endowment for MCC Research; and the University of Washington MCC Patient Gift Fund.

    Conflicts of interest: None declared.

    These authors contributed equally to this study.

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