Histopathological Aspects of the Prognostic Factors for Salivary Gland Cancers

Simple Summary We describe the currently known histopathological aspects of the prognostic factors for salivary gland cancers and discuss the genetics or molecules used as diagnostic tools that might serve as treatment targets in the future. Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial-myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.

Automated summary

We summarize the histopathological characteristics of prognostic factors for salivary gland cancers (SGCs) and discuss the potential diagnostic and treatment targets of genes or molecules. SGCs are diagnosed through histopathological examination, which greatly influences their progression, including metastasis and recurrence. The WHO Classification of Head and Neck Tumors categorizes malignant and benign epithelial tumors into different types. MEC, AdCC, salivary duct carcinoma, salivary carcinoma, NOS, myoepithelial carcinoma, epithelial-myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma are commonly seen types. While some have specific grading systems, a universal grading system has not been recommended for SGCs. On the other hand, cautious treatment is required for PA to prevent metastasis or recurrence.