Clinicopathologic features as stronger prognostic factors than histology or grade in risk stratification of primary parotid malignancies

Background. The aim of this study, using a retrospective chart review as the primary study design, was to determine the relative contribution of clinicopathologic risk factors versus low‐ and high‐risk grade histologic groups to assist management of primary parotid cancers. Methods. In all, 168 primary parotid malignancies were treated surgically at a tertiary care center from 1982 to 2005. Of these, 115 patients with complete follow‐up information were further analyzed. Pathologic updating and reclassification in 28% of cases enabled comparison of tumor histology or grade with current consensus criteria. Clinical outcomes of high‐ and low‐risk histology and grade were compared with the influence of traditional clinicopathologic risk factors. Results. Of 115 cases, the male:female ratio was equal and the median age was 63 years (range, 15 to 89 years). Mucoepidermoid carcinoma (n = 28) was the most common histology. The median follow‐up was 44 months (range, 0–278 months). Of low‐risk histology patients who underwent neck dissection 40% had pN+ disease. The median time to recurrence was not reached for low‐risk tumors, compared with 29 months for high‐risk tumors (p = .0001). Interestingly, extracapsular spread (ECS) and margin status were independent prognostic factors and conferred significantly greater prognostic value than histologic grade risk group. Disease‐free survival (DFS) and overall survival (OS) at 5 years for the entire cohort were 51% and 57%, respectively. Risk group was a strong independent predictor of OS but not DFS Conclusions. Risk group defined by histology and grade was associated with DFS. ECS and margin status were independent predictors of DFS. Inclusion of ECS and margin status substantially improved the prediction of disease recurrence, supporting elective neck dissection and postoperative radiotherapy for high‐grade tumors or low‐risk histologies with positive margins or ECS. © 2010 Wiley Periodicals, Inc. Head Neck, 2011