Primary tumor site for localized Merkel cell carcinoma drives different management strategies without impacting oncologic outcomes

• Published in: Radiotherapy and oncology Vol. 188; p. 109892
• Main Authors: Cass, Samuel, Cope, Brandon, Bishop, Andrew J., Chiang, Yi-Ju, Ashleigh Guadagnolo, B., Farooqi, Ahsan, Morrison, William, Witt, Russell G., Seervai, Riyad N.H., Garden, Adam S., Fuller, Clifton D., Goepfert, Ryan P., Ross, Merrick, Gershenwald, Jeffrey E., Wong, Michael, Aung, Phyu P., Keung, Emily Z., Mitra, Devarati
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.11.2023
• Subjects: Aged; Aged, 80 and over; Anatomic site; Carcinoma, Merkel Cell - mortality; Carcinoma, Merkel Cell - pathology; Carcinoma, Merkel Cell - radiotherapy; Carcinoma, Merkel Cell - therapy; Female; Head and Neck Neoplasms - mortality; Head and Neck Neoplasms - pathology; Head and Neck Neoplasms - radiotherapy; Head and Neck Neoplasms - therapy; Humans; Male; Merkel cell carcinoma; Middle Aged; Neoplasm Recurrence, Local; Neoplasm Staging; Radiation therapy; Radiotherapy, Adjuvant; Retrospective Studies; Skin Neoplasms - mortality; Skin Neoplasms - pathology; Skin Neoplasms - radiotherapy; Skin Neoplasms - therapy; Surgery; Treatment Outcome; CLND; RT; Anatomic site; Merkel cell carcinoma; HN; Radiation therapy; SLNB; MCC; WLE; RC; MCSS; SLN; NHN; NC; Surgery; DMFS; LC; cLN(-); RFS
• ISSN: 0167-8140; 1879-0887; 1879-0887
• DOI: 10.1016/j.radonc.2023.109892

•For MCC patients who received RT, practice patterns varied by primary tumor site.•Patients with head & neck MCC had less surgery and more radiation therapy.•Despite practice variance by tumor site, patients had similar locoregional control.•Given similar outcomes, patient-centric approaches for management are warranted. Clinically localized Merkel cell carcinoma (MCC) has been associated with high rates of disease relapse. This study examines how primary tumor anatomic site drives patterns of care and outcomes in a large cohort treated in the contemporary era. Patterns of care and associated outcomes were evaluated for clinically Stage I-II MCC patients treated at our institution with adjuvant radiation therapy (RT) to the primary site and/or regional nodal basin as a component of their curative intent therapy between 2014–2021. Of 80 patients who met inclusion criteria, the primary tumor anatomic site was head and neck (HN) for 42 (53%) and non-head and neck (NHN) for 38 (47%). Primary tumor risk factors were similar between cohorts. Fewer patients with HN tumors had wide local excision (WLE; HN-81% vs. NHN-100% p < 0.01). Of those undergoing WLE, patients with HN tumors received higher dose adjuvant RT (>50 Gy: HN-70% vs. NHN-8%; p < 0.01). Patients with HN tumors were less likely to undergo sentinel lymph node biopsy (HN-62%vs. NHN-100%; p < 0.01) and more likely to have elective nodal RT (HN-48% vs. NHN-0%). Despite varying management strategies, there was no significant difference in local recurrence-free survival (3-yr LRFS HN-94% vs. NHN-94%; p = 0.97), nodal recurrence-free survival (3-yr NRFS HN-89% vs. NHN-85%; p = 0.71) or overall recurrence-free survival (3-yr RFS 73% HN vs. 80% NHN; p = 0.44). Among patients with primary MCC who had RT as a component of their initial treatment strategy, anatomically-driven heterogeneous treatment approaches were associated with equally excellent locoregional disease control.