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.