Significance of clinical stage,extent of surgery,and pathologic findings in metastatic cutaneous squamous carcinoma of the parotid gland

BACKGROUND: Metastatic cutaneous cancer is the most common parotid malignancy in Australia, with metastatic squamous carcinoma (SCC) occurring most frequently. There are limitations in the current TNM staging system for metastatic cutaneous malignancy, because all patients with nodal metastases are simply designated N1, irrespective of the extent of disease. The aim of this study was to analyze the influence of clinical stage, extent of surgery, and pathologic findings on outcome after parotidectomy for metastatic SCC by applying a new staging system that separates metastatic disease in the parotid from metastatic disease in the neck. METHODS: A prospectively documented series of 87 patients treated by one of the authors (COB) over 12 years for clinical metastatic cutaneous SCC involving the parotid gland and a minimum of 2 years follow-up was analyzed. These patients were all previously untreated and were restaged according to the clinical extent of disease in the parotid gland in the following manner. P1, metastatic SCC of the parotid up to 3 cm in diameter; P2, tumor greater than 3 cm up to 6 cm in diameter or multiple metastatic parotid nodes; P3, tumor greater than 6 cm in diameter, VII nerve palsy, or skull base invasion. Neck disease was staged in the following manner: N0, no clinical metastatic disease in the neck; N1, a single ipsilateral metastatic neck node less than 3 cm in diameter; N2, multiple metastatic nodes or any node greater than 3 cm in diameter. RESULTS: Clinical P stages were P1, 43 patients; P2, 35 patients; and P3, 9 patients. A total of 21 patients (24%) had clinically positive neck nodes. Among these, 11 were N1, and 10 were N2. Conservative parotidectomies were carried out in 71 of 87 patients (82%), and 8 of these had involved surgical margins (11%). Radical parotidectomy sacrificing the facial nerve was performed in 16 patients, and 6 (38%) had positive margins, (p <.01 compared with conservative resections). Margins were positive in 12% of patients staged P1, 14% of those staged P2, and 44% of those staged P3 (p <.05). Multivariate analysis demonstrated that increasing P stage, positive margins, and a failure to have postoperative radiotherapy independently predicted for decreased control in the parotid region. Survival did not correlate with P stage; however, many patients staged P1 and P2 also had metastatic disease in the neck. Clinical and pathologic N stage both significantly influenced survival, and patients with N2 disease had a much worse prognosis than patients with negative necks or only a single positive node. Independent risk factors for survival by multivariate analysis were positive surgical margins and the presence of advanced (N2) clinical and pathologic neck disease. CONCLUSIONS: The results of this study demonstrate that patients with metastatic cutaneous SCC in both the parotid gland and neck have a significantly worse prognosis than those with disease in the parotid gland alone. Furthermore, patients with cervical nodes larger than 3 cm in diameter or with multiple positive neck nodes have a significantly worse prognosis than those with only a single positive node. Also, the extent of metastatic disease in the parotid gland correlated with the local control rate. The authors recommend that the clinical staging system for cutaneous SCC of the head and neck should separate parotid (P) and neck disease (N) and that the proposed staging system should be tested in a larger study population.