N1S3: a revised staging system for head and neck cutaneous squamous cell carcinoma with lymph node metastases: results of 2 Australian Cancer Centers.

BACKGROUND: A staging system was designed for metastatic cutaneous squamous cell carcinoma (SCC) that would incorporate the parotid as a regional level and facilitate a better prognostic discrimination between subgroups.
METHODS: A retrospective review of clinical and pathological information of patients treated for metastatic cutaneous SCC to the parotid and/or neck was conducted. Potential prognostic factors were analyzed using univariate and multivariate analyses. A staging system was elaborated and externally validated.
RESULTS: Two hundred fifteen patients were included. All patients had surgery as their primary treatment; 148 had parotidectomy with neck dissection, 50 parotidectomy alone, and 18 neck dissection alone. One hundred seventy-five patients received postoperative radiotherapy. On univariate analysis, the number of involved lymph nodes (P < .001), maximal size (P = .01), and extracapsular spread (P = .003) were found to be significant predictors of survival. On Cox regression, the number of involved lymph nodes as single or multiple (P = .006) was significant. The N1S3 staging system incorporates involved lymph nodes from parotid and neck (single or multiple) and the size (< or >3 cm). This system demonstrates significant predictive capacity for locoregional control (P < .001), disease-specific survival (P<.0001), and overall survival (P<.0001). N1S3 was tested on a different cohort of 250 patients, and the results confirmed those obtained from our primary analyses.
CONCLUSIONS: The N1S3 system stages patients according to the number of involved lymph nodes and size, and incorporates parotid as 1 of the regional levels. These 2 predictors are easily applied on both clinical and pathological data.