Clinicopathologic Features and Prognostic Factors of Widely Invasive Carcinoma Ex Pleomorphic Adenoma of Parotid Gland: A Clinicopathologic Analysis of 126 Cases in a Chinese Population.

ABSTRACT

PURPOSE: Salivary intracapsular carcinoma ex pleomorphic adenoma (ICCXPA) and minimally invasive CXPA (MICXPA) generally have favorable outcomes. In contrast, widely invasive CXPA (WICXPA) frequently results in disease-related death. The aims of the present study were to analyze the differences in the clinicopathologic features between parotid gland ICCXPA or MICXPA and WICXPA and the prognostic factors for WICXPA. MATERIALS AND METHODS: We performed a retrospective cohort study. The clinicopathologic parameters of patients with primary CXPA of the parotid gland from our 2001 to 2012 cohort were reviewed. The predictor variable was a set of heterogeneous factors grouped into demographic, clinical, and pathologic features. The primary outcome variable was the tumor diagnosis, grouped into 3 categories ICCXPA, MICXPA, and WICXPA. For statistical analysis, ICCXPA and MICXPA were combined into 1 group, with WICXPA analyzed separately. The differences in the clinicopathologic parameters between the 2 groups (ICCXPA plus MICXPA vs WICXPA) were evaluated using the χ2 test or t test. The secondary outcome variable was disease-specific survival (DSS) of those with WICXPA. The survival data for WICXPA were statistically analyzed using the Kaplan-Meier method and Cox regression. RESULTS: A total of 241 cases of CXPA had been diagnosed, including 63 cases of ICCXPA, 52 cases of MICXPA, and 126 cases of WICXPA. The patients with WICXPA were older than were those with ICCXPA/MICXPA (59.6 vs 51.4 years; P < .001) and had a larger tumor diameter (3.9 vs 3.3 cm; P = .040). The proportion of histologic high-grade tumor (P < .001), proportion of carcinoma more than 50% (P < .001), and proportion of lymph node involvement (P < .001) was greater in those with WICXPA. Cox regression analysis indicated that age, T stage, and N stage were independent prognostic factors of DSS for those with WICXPA. CONCLUSIONS: Older age, later T stage, a greater proportion of carcinoma, histologic high-grade findings, and lymph node involvement were associated with parotid gland WICXPA. Age, T stage, and N stage were the important independent factors for predicting the prognosis of patients with parotid gland WICXPA.