Breast cancer metastasizing to salivary glands: Systematic review

Distant metastasis to salivary glands is a very rare event and most often associated with primary malignancies of the skin. Only 1-4% of all salivary gland tumours manifest with metastasis. Carcinomas of the breast, lung, kidney and prostate are those primaries that may also potentially metastasize to salivary glands. Literature has documented several studies analysing metastatic tumours in the oral region. However, very little research work has been published to date to analyse solely the Breast cancer metastasizing to the salivary glands. Thus, this review was conducted to examine the published cases of Breast cancer metastasizing to salivary glands from March 1975 to March 2023. An electronic search of the published literature was performed without publication year limitation in PubMed/ Medline, Scopus, Google Scholar, Web of Science, Science Direct, Embase, and Research Gate databases, using mesh keywords like ('Breast cancer' OR 'Breast carcinoma') AND ('Metastasis' OR 'Metastases'), And ('Salivary glands' OR 'Parotid gland' OR 'Submandibular gland' OR 'Sublingual gland'). We also searched all related journals manually. The reference list of all articles was also checked. Our research revealed a total of 48 relevant papers with 55 patients. Parotid was the most predominantly affected salivary gland. 14.5% of patients died with a mean survival time of 7 months. It can be concluded from this research that Breast cancer metastasizing to salivary glands is a rare occurrence. Careful evaluation of these cases is needed in order to raise awareness of these lesions and gain a better understanding of their characteristics.