Tumor classification of adenoid cystic carcinoma: systematic review and meta-analysis.

Adenoid Cystic Carcinoma - ACC is a common neoplasm in major and minor salivary glands with a high risk of metastasis. Thus, the objective of the present study was to perform an analysis to better understand the histological grading systems of the ACC and its influence on tumor prognosis in terms of overall survival, disease-free and metastasis-free. This is a systematic review, with meta-analysis, based on the PRISMA parameters. The search was carried out by two independent examiners, and searches were performed in the PubMed, Web of Science, Scopus, Science Direct, and Google Scholar databases. Of the 12 articles included in the systematic review, only 7 met the eligibility criteria for entry into the meta-analysis, with a statistically significant association between tumors with a solid pattern and death from the disease (DOD) (p <0.001; 95% CI 2.84 [1.94-4.15]; I 2 61%). Regarding the evaluation of the quality of studies by the Quality in Prognostic Studies (QUIPS), six studies were of high quality, five articles received moderate quality, and one article received low quality. It was concluded that the presence of any solid component contributes to a worse prognosis and lower specific survival of the disease over the 10 years.