Oral Soft Tissue Metastasis from Breast Cancer as the Only Primary Source: Systematic Review

Background  Breast cancer is one of the most lethal neoplasms causing death. Oral cavity is the rare site of distant metastasis from breast cancer. Very little research has been conducted to date to analyze breast cancer as the sole primary source of metastasis to the oral soft tissues. The goal of this study was to examine the published cases of oral soft tissue metastasis from breast cancer as the only primary source to date. Methods  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 ("Oral soft tissues" OR "Tongue" OR "Palate" OR "Tonsil" OR "Buccal mucosa" OR "Floor of mouth" OR "Vestibule" OR "Salivary glands"). We also searched all related journals manually. The reference list of all articles was also checked. Results  Our research revealed 88 relevant papers (September 1967-September 2023) with 96 patients in total. The most predominant oral soft tissues involved were salivary glands followed by the gingiva, tonsils, tongue, and buccal mucosa. A total of 23% of patients died with an average survival time of 1 to 15 months. Conclusions  Oral soft tissue metastasis from breast cancer is a rare event and has a bad prognosis. More cases need to be published to raise awareness of these lesions.