Lung Metastasis

Excerpt

Metastasis is the spread of tumor cells from primary sites to surrounding structures and distant sites. It is considered a significant cause of morbidity and mortality. Distant metastasis is an indicative marker of the aggressive nature of the primary tumor.

Metastasis in the lung is a complex multistep process. Metastatic tumor cells undergo stages of detachment from the primary tumor sites, invasion into vessels (capillary, lymphatics), extravasation into the appropriate secondary site, and establishment of a microenvironment supporting its nourishment and blood supply. Common cancers that metastasize to lung parenchyma include breast, lung, colorectal cancer, uterine leiomyosarcoma, and head/neck squamous cell carcinomas. Cancers that spread to the endobronchial tree of the lungs include colorectal, renal, lung cancer, and lymphomas. Other tumors that can metastasize to the lungs include osteosarcoma and testicular tumors. Other rare cancers described in the literature that metastasize to the lung include adrenal, thyroid, choriocarcinoma, and hypernephroma. Some tumors cannot be identified and classified as cancer of unknown primary (CUP). Around 90% of CUP are adenocarcinomas (90%), with squamous cell carcinomas and undifferentiated carcinomas reportedly less frequent.