Our team based in Seattle conducted a comprehensive review including evolving trends in the management of Merkel cell carcinoma (MCC). This summary covers key decision points, including recommended work-up during initial diagnosis, treatment options for MCC when it’s in one place or has spread, management of recurrent MCC, and new treatments that are showing promise with fewer side effects and good results. This review gives valuable information on how to handle MCC overall and emphasizes new methods that are effective and less toxic on patients.
BACKGROUND: Merkel cell carcinoma (MCC) guidelines derive from melanoma and do not recommend baseline cross-sectional imaging for most patients. However, MCC is more likely to have metastasized at diagnosis than melanoma.
OBJECTIVE: To determine how often baseline imaging identifies clinically occult MCC in newly diagnosed patients with and without palpable nodal involvement.
METHODS: Analysis of 584 MCC patients with a cutaneous primary, baseline imaging, no evident distant metastases, and sufficient staging data.
RESULTS: Among 492 patients with clinically uninvolved regional nodes, 13.2% were upstaged by imaging (8.9% in regional nodes, 4.3% in distant sites). Among 92 patients with clinically involved regional nodes, 10.8% were upstaged to distant metastatic disease. Large (>4cm) and small (<1cm) primary tumors were both frequently upstaged (29.4% and 7.8%, respectively). PET-CT upstaged patients more often (16.8% of 352), than CT alone (6.9% of 231; p=0.0006).
LIMITATIONS: This was a retrospective study.
CONCLUSIONS: In clinically node-negative patients, baseline imaging revealed occult metastatic MCC at a higher rate than reported for melanoma (13.2% vs. <1%). Although imaging is already recommended for clinically node-positive MCC patients, these data suggest that baseline imaging is also indicated for clinically node-negative patients because upstaging is frequent and markedly alters management and prognosis.