Histocytologic grading of mucoepidermoid carcinoma of major salivary glands in prognosis and survival: a clinicopathologic and flow cytometric investigation.

Background: Controversy exists regarding the role of a 3-tiered grading system for mucoepidermoid carcinoma (MEC) of salivary glands in prognosis and survival. This retrospective investigation evaluated a 3-tiered grading system modified from Healey by Batsakis and Luna and compared various clinical, pathologic, and flow cytometric parameters and overall survival among MECs of differing grades.

Methods: Forty-eight patients with 7 low-grade (LG), 23 intermediate-grade (IG), and 18 high-grade (HG) MECs of parotid (n = 43) and submandibular (n = 5) glands were studied. Data were analyzed using categorical statistics (Wilcoxon, Kruskal-Wallis and Chi-squared tests where appropriate).

Results: Mean ages were 42 years for patients with LG tumors; 47 years, IG; and 59 years, HG (p = 0.02). Gender ratio (p < 0.001) changed from female predominance in LG (6 F:1 M) and IG (2.1 F:1 M) to male predominance in HG (3.5 M:1 F). Mean tumor stage was 1.4 LG, 2.4 IG, and 3.6 HG (p < 0.005). Tumor size increased from 2.1 cm for LG to 3.8 cm for HG (p = 0.01). Margins were involved by tumor in 0% LG, 44% IG, and 61% HG (p < 0.001). Lymph node involvement was 0% LG, 22% IG, and 72% HG (p < 0.001). DNA aneuploidy (DNA index < 0.9 or > 1.1) was present in 0% LG, 13% IG, and 28% HG (p = 0.05). Proliferative fraction (S + G2M) was 5% LG, 7% IG, and 13% HG (p = 0.008). Radiotherapy was administered in 14% LG, 35% IG, and 61% HG (p = 0.03). Recurrences (local and/or metastatic) occurred in 0% LG, 39% IG, and 61% HG (p = 0.009). Survival was decreased significantly (p < 0.0001) with increasing tumor grade (100% LG, 70% IG, and 22% HG).

Conclusions: Histologic grading of mucoepidermoid carcinomas of major salivary glands, using the modified Healey 3-tiered system, correlates well with clinical, pathologic, and flow cytometric factors which influence the prognosis and overall survival in affected individuals.