Parotid metastasis--an independent prognostic factor for head and neck cutaneous squamous cell carcinoma.

BACKGROUND: Metastatic parotid cutaneous squamous cell carcinoma (SCC) is the most common parotid gland malignancy in New Zealand and Australia. The current AJCC TNM staging system does not account for the extent of nodal metastasis. A staging system that separates parotid (P stage) from neck disease (N stage) has been proposed recently. AIM: To review the outcome of patients with metastatic head and neck cutaneous SCC treated at our multidisciplinary Head and Neck Service using the proposed staging system.
METHOD: Consecutive patients were culled from our Head and Neck/Skull Base Database, 1990-2004. These patients were restaged according to the proposed staging system: P stage: P0 = no disease in the parotid (i.e., neck disease only); P1 = metastatic node < or = 3 cm; P2=metastatic node > 3 cm and < or =6 cm, or multiple nodes; and P3 = metastatic node > 6 cm, or disease involving the facial nerve or skull base. N stage: N0=no disease in the neck (i.e., parotid disease only); N1 = single ipsilateral metastatic node < or = 3 cm; and N2 = multiple metastatic nodes, or any node > 3 cm, or contralateral neck involvement. Loco-regional recurrence and disease-specific survival were calculated using the Kaplan-Meier method and comparison of graphs made with the log-rank test. Multivariate analysis using the Cox regression model was carried out to assess the impact of various parameters.
RESULTS: Sixty-seven patients with metastatic head and neck cutaneous SCC were identified. Thirty-seven patients had parotid metastasis (of whom 13 also had neck disease) while 21 had neck metastasis alone. Nine patients had dermal or soft tissue metastasis. These nine patients were excluded from this series, and data analysis was carried out on the remaining 58 (46 men, 12 women, mean age 71 years) patients. Sixty-seven percent of the patients underwent post-operative adjuvant radiotherapy. The five-year disease-specific survival rate was 54%. Among 56 patients followed up to disease recurrence or for a minimum period of 18 months, the loco-regional recurrence rate was 52%. The presence of parotid disease was an independent prognostic factor on survival (p < 0.01), and P3 fared significantly worse than P1 and P2. Those patients who had both parotid and neck disease fared worse than those who had parotid or neck disease alone (p = 0.01). N2 had a significantly poorer outcome compared with N1 (p < 0.01). Immunosuppression (p = 0.01) and a positive surgical margin (p < 0.01) were significant adverse prognostic factors for survival. Adjuvant radiotherapy, extracapsular spread, and perineural and vascular invasion did not influence survival. Our study demonstrates that the extent of parotid disease is an independent prognostic factor for metastatic head and neck cutaneous SCC.