Carcinoma of the parotid gland: developing prognostic indices

Prognosis for parotid carcinomas is not-well defined. The authors have developed models that could be useful to define subgroups of patients with differential risks. Clinical and pathological variables, and immunohistochemically studied MMP-7, MMP-9, MT1-MMP, and VEGF proteins were analysed in 42 patients with parotid gland cancer, regarding disease-specific survival and loco-regional recurrence. A prognostic index (PI) was calculated by combining age, disease stage, squamous cell carcinoma histology, and vascular endothelial growth factor immunoexpression. Based on the values of this PI, patients were classified into three groups: 1.89-4.18 (SPI1); 4.2-7 (SPI2), and >7 (SPI3). Corresponding 5-year survival rates for these groups of patients were of 89%, 47%, and 21%, respectively. Regarding loco-regional recurrence three different patient groups were calculated combining three factors: T, N and grade. Differences amongst them were statistically significant and the estimated hazard ratios were 6.4 and 24.2 for intermediate and poor prognosis, respectively, taking the good prognostic group as reference. The authors identified several significant prognostic factors and they propose two PIs for disease-specific survival and for loco-regional recurrence. They allow for the calculation of death risk and recurrence for a given patient, providing a practical system for clinical use.