2787 - Impacts of Elective Neck Management for Cutaneous Carcinomas with Intraparotid Nodal Metastasis
Presenter(s)
D. F. Leach III1, M. H. Chen2, H. Zhu2, Y. Chavis1, S. R. Khandelwal3, P. W. Read1, and C. McLaughlin1; 1Department of Radiation Oncology, University of Virginia Health, Charlottesville, VA, 2Department of Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA, 3Department of Radiation Oncology, University of Virginia, Charlottesville, VA
Purpose/Objective(s): Cutaneous carcinomas of the head and neck often metastasize to the intraparotid and/or periparotid lymph nodes, known as the parotid area lymph nodes (PALN). Approximately 80% of cases involving PALN arise from cutaneous squamous cell carcinoma (SCC), followed by malignant melanoma (MM), Merkel cell carcinoma (MCC), and basal cell carcinoma. Management of these cases typically involves superficial parotidectomy, followed by postoperative radiotherapy (PORT). For such patients, elective management of the neck can involve neck dissection (ND) and/or PORT as well. We hypothesize that with involved PALN after parotidectomy, progression free survival (PFS) is superior with ND and PORT versus PORT alone.
Materials/Methods: Cases of cutaneous carcinomas involving the PALN and treated with PORT at our institution between 2013 and 2023 were identified. A retrospective review was performed to collect clinical outcomes and patient characteristics, and descriptive analysis was performed. For overall survival (OS) and PFS, hazard ratios (HR) were calculated from multivariable Cox regression models. For locoregional failure (LRF) and distant metastasis (DM), subdistribution hazard ratios (subHR) were computed from multivariable Fine-Gray subdistribution hazard regression models. Multivariable models (MVA) included 1) skin cancer type as strata and 2) ND vs no ND, 3) extranodal extension (ENE) vs no ENE, 4) RT volume, and 5) immunocompromised (IC) status as fixed effects. Age, TNM and overall stage, perineural invasion (PNI), and positive/close margins were included in MVA only when significant and were removed using backwards selection with p=0.05 as the threshold.
Results: 50 patients with cutaneous carcinomas metastatic to the PALN were included with 40 exhibiting SCC and 10 exhibiting MM or MCC. Fifty percent of patients exhibited ENE. All patients underwent parotidectomy, and 68% of patients received nodal surgery with parotidectomy plus ND. All patients received PORT, with a median dose of 66 Gy in 33 fractions. ND positively impacted LRF (subHR 0.16, p=0.03) and OS (HR 0.19, p=0.04) with a trend towards improved PFS (HR 0.40, p=0.18). Excluding the parotidectomy bed in the PORT volumes negatively impacted both OS (HR of 7.65, p=0.04) and PFS (HR of 10.40, p<0.01). ENE within the parotid was not statistically significant for OS, PFS, LRF, or DM. PNI and positive/close margins did not impact outcomes. IC negatively impacted both OS (HR 7.87, p<0.01) and PFS (HR 6.13, p<0.01).
Conclusion: In this analysis, the addition of a neck dissection to parotidectomy improved OS, even though all patients received PORT. The survival detriment of IC has been previously reported, and our results are consistent with that. However, ENE did not affect survival, which suggests PORT adequately addresses microscopic residual disease in this context. This study is limited by its retrospective nature, and the improved survival with ND warrants prospective evaluation.