2307 - Merkel Cell Carcinoma of the Scalp: The Effect of Head and Neck Anatomic Subsite on Recurrence Patterns and Outcomes
Presenter(s)
M. Bian1, N. X. Yang2, A. F. M. Salem3, A. J. Bishop3, R. G. Witt4, A. K. Yoder3, A. Farooqi3, B. A. Guadagnolo3, A. S. Garden3, C. D. Fuller5, R. P. Goepfert2, P. P. Aung6, E. Z. Keung7, W. H. Morrison3, A. Lee3, and D. Mitra3; 1Case Western Reserve University School of Medicine, Cleveland, OH, 2The University of Texas MD Anderson Cancer Center, Houston, TX, 3Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 4University of Virginia, Charlottesville, VA, 5Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 6MD Anderson Cancer Center, Houston, TX, 7Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose/Objective(s): Merkel cell carcinoma (MCC) is a rare aggressive skin cancer for which outcomes may vary by anatomic site. This study evaluates patterns of care and outcomes for scalp (S) vs non-scalp (NS) head and neck (HN) MCC at a tertiary referral center.
Materials/Methods: We searched our institutional databases for stage I-II HN MCC (cN0M0) treated between 1996-2024. S was defined as the hair-bearing occipitofrontoparietal region of the head. Clinicopathologic variables for S vs. NS pts were compared by the Mann-Whitney or Fisher’s Exact tests. Local recurrence was defined as recurrence within 2 cm of the primary surgical bed and non-nodal locoregional recurrence was defined as recurrence that was either local or in transit. Time to events was assessed by the Kaplan-Meier method with comparisons by the log-rank test.
Results: 138 pts were included; 20 (14%) were S pts vs. 118 (84%) with NS disease. Median age for S and NS were 72 years and 71 years, respectively (p=0.60). Male sex was more common for S pts (85% vs 52%, p=0.004). Rates of immunocompromise were 20% vs. 13% for S and NS pts, respectively (p=0.38).
Primary tumor sizes were median 4.5 mm for S pts [IQR 3.0-8.2] vs. 6.1 mm for NS pts [IQR 3.6-12.8], (p=0.10) and LVI rates were 28% vs. NS-41% (p=0.16) for S and NS pts respectively. Margin status was known for 18 S pts and 82 NS pts with 44% vs. 58% being positive (p=0.27) Most pts underwent wide local excision (S-75% vs. NS-76%) as primary treatment. The remainder received primary radiotherapy (RT). Sentinel lymph node biopsy (SLNB) rates were S-60% vs. NS-53%, (p=0.38). The majority of pts received primary site RT (S-95% vs. NS-93%, p=1.0). S pts were less likely to receive elective nodal RT (S- 42% vs. NS-66%, p=0.045). Among 10 pts who did not receive SLNB, S pts were numerically more likely to receive elective nodal RT (S-50% vs. NS-33%, p=1.0). Adjuvant systemic therapy was uncommon (S-5% vs. NS-9%, p=1.0) and consisted of platinum/etoposide doublet or anti-PD1 immunotherapy. Median follow up was S-31 months [IQR 15-62] vs. NS-45 months [IQR 19-61] (p=0.33). S pts experienced worse local recurrence-free survival (3-year LRFS 84% vs. 94%, p=0.04) and non-nodal locoregional recurrence free survival (3-year NNLRFS 77% vs. 96%, p=0.024). There were no significant differences in nodal-recurrence-free survival or disease-free survival between cohorts. Crude recurrences (% of cohort) are as follows – local: 3 S (15%) vs 5 NS pts (4%); regional: 2 S (10%) vs 4 NS pts (3%); distant: in 3 S pts (15%) vs 18 NS pts (15%).Conclusion: Stage I-II MCC of the S and NS regions were managed similarly at our institution. However, S pts had a higher likelihood of local or in-transit recurrence. Improved strategies to maximize local control for pts with scalp MCC are warranted.