Lung cancer metastasizing to salivary glands: Systematic review

Metastasis to salivary glands from the secondary source outside the head and neck region is extremely rare and Carcinoma Lung is one of the rarest sources of distant spread to salivary glands. Owing to missed diagnosis and misdiagnosis, accurate identification of clinical and pathological aspects of these metastatic lesions remains a challenging task. Many studies regarding metastasis to the oral cavity have been already documented in the literature, but very little research work has been done to analyse the cases of lung cancer metastasis as the sole primary source, particularly to salivary glands. Thus this review was conducted to analyse the published cases of lung cancer metastasizing to salivary glands as the only primary source till date. 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 (Lung cancer', OR 'Lung 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 34 relevant papers between 1965-2022 with a total of 44 patients. The most prevalent diagnosed metastatic Lung cancer was Small cell lung cancer. Parotid was the most common gland involved in metastasis. 48% of patients died of metastasis with a mean survival time of 2.2 years. Salivary gland metastasis from Lung cancer is very rare and has a poor prognosis. More cases need to be published in order to raise awareness of these lesions and gain a better understanding of their characteristics.