Merkel cell carcinoma: does tumor size or depth of invasion correlate with recurrence, metastasis, or patient survival?

OBJECTIVE

The objective of this retrospective study and literature review was to compare the clinical and histologic criteria including tumor size and depth of invasion with outcomes in patients with Merkel cell carcinoma.

METHODS

The state cancer registry provided patients (n = 46) diagnosed with Merkel cell carcinoma from 1992 through 2002. Pathology slides were reviewed by the author for tumor size, depth of invasion, Clark level, and margin status. Further clinical information and survival data were gathered from patient records. Statistical analysis was performed using t tests and Kaplan-Meier survival curves. Patients were excluded from specific analysis based on misdiagnosis, unavailability of pathology slides, absent medical records, or those lost to follow up.

RESULTS

Disease-free survival rates were 52%, 39%, and 9% at 1, 2, and 5 years, respectively. The average disease-free interval was 18.4 months (range, 1-80 months). No correlation was found between tumor size (P = .49), depth (P = .41), or Clark level (P = .82) to overall survival. A trend was found comparing tumor size or depth of invasion with local recurrence (P = .07) but with no correlation to regional recurrence (P = .93 and P = .60) or distant metastasis (P = .16 and P = .24). Overall recurrence was found in 60.7% of patients with local recurrence occurring in 18.1%, regional recurrence 40.9%, and distant recurrence 47.8%. Comparing patients with positive versus negative margins at initial excision, local recurrence was found in 33.3% versus 9.09% (P = .19), regional recurrence 66.6% versus 27.2% (P = .08), and distant metastasis 66.6% versus 45.4% (P = .36), respectively.

CONCLUSIONS

No correlation was found between tumor size or depth of invasion to patient survival or metastasis. However, there was a trend toward increased local and regional recurrence rates when comparing size and depth and in specimens with positive tumor margins. These outcomes are consistent with those reported in recent literature and further characterize the unpredictable nature of this disease. An aggressive approach should be taken, including wide local excision with negative tumor margins and lymph node dissection; however, larger multistate reviews are needed for additional support.