Systematic review of prognostic factors in carcinoma ex pleomorphic adenoma

Carcinoma ex Pleomorphic Adenoma (CXPA) is a rare primary salivary gland malignancy, typically arising from a pre-existing pleomorphic adenoma. This systematic review examines prognostic factors affecting overall survival (OS) in major and minor salivary gland CXPA. Systematic review of MEDLINE, Cochrane, Scopus, Web of Science, CINAHL, and Open Grey databases from inception to 31st March 2022 for all English-language literature pertaining to ‘carcinoma ex pleomorphic adenoma’. All study types with greater than five patients with CXPA of the major and minor salivary glands were eligible for inclusion. Of 8143 studies, 39 studies (n = 5637 patients) meeting the inclusion criteria were included. Median OS at one, three, five, and ten years were 90.0 %, 72.0 %, 61.9 %, and 45.0 % respectively for all CXPA. Higher staging, T stage, nodal disease, grading, and invasion ≥ 1.5 mm had worse outcomes. Histological subtype, perineural invasion, and radiotherapy did not demonstrate a consistent trend. Three studies were evaluated to have high risk of bias, and was removed for sensitivity analysis. Survival outcomes worsen with time for all salivary gland CXPA. Further research on histopathological features and the utility of radiation therapy is required to guide patient selection for more aggressive treatment. Registration: CRD42021238544 (PROSPERO)