Metastázist

Metastázist is a biological process where cancer cells move from the primary tumor to other parts of the body and form new tumors. This spread typically occurs through the bloodstream or the lymphatic system. When cancer cells detach from the original tumor, they can enter these circulatory pathways and travel to distant organs. Once they arrive at a new site, they can establish secondary tumors, known as metastases. This process significantly complicates cancer treatment and is often associated with a poorer prognosis.

The development of metastases involves several steps. First, cancer cells must invade the surrounding tissues and enter the bloodstream or lymphatic vessels. This is facilitated by enzymes that break down the extracellular matrix. Once in circulation, these cells, often called circulating tumor cells (CTCs), must survive the journey, which can be challenging due to immune surveillance and mechanical stress. Upon reaching a suitable organ, the CTCs must arrest their movement, adhere to the vessel walls, and extravasate, meaning they exit the bloodstream into the new tissue. Finally, these cells must proliferate and form a clinically detectable secondary tumor, a process that requires them to adapt to the new microenvironment and overcome local anti-tumor defenses.

The most common sites for metastasis depend on the primary cancer type. For example, breast cancer often spreads to the bones, lungs, liver, and brain. Lung cancer can metastasize to the brain, bones, liver, and adrenal glands. Understanding the mechanisms of metastasis is crucial for developing effective diagnostic and therapeutic strategies. Current treatments aim to prevent or slow down this spread, often involving chemotherapy, radiation therapy, targeted therapies, and immunotherapy, in addition to surgery to remove the primary tumor.