Metastasis Explained: How Cancer Spreads

In the initial stage of metastasis, cancer cells must break free from the primary tumor.These cells are normally held together by adhesion molecules, which act like cellular glue.To break free, cancer cells produce special proteins called proteases.These proteases break down the surrounding tissue and the basement membrane, creating a path for escape.The cells then undergo a remarkable transformation called epithelial-mesenchymal transition, or EMT.During EMT, cells change their structure dramatically. They become more flexible and mobile, losing their rigid epithelial characteristics.This transformation allows the cancer cells to move more freely through the surrounding tissue, beginning their journey toward metastasis.After breaking free from the primary tumor, cancer cells must enter the bloodstream through a process called intravasation.Inside the bloodstream, cancer cells face numerous challenges. They must navigate through rapidly flowing blood cells while avoiding detection.The immune system actively patrols the bloodstream. Specialized immune cells can recognize and attempt to destroy cancer cells.To survive, cancer cells often form clusters with platelets and other blood cells. These clusters provide protection and increase survival chances.The journey through the bloodstream is extremely challenging. Only about one in ten thousand cancer cells survives this process.Those few cells that do survive can travel to distant sites in the body, protected by their platelet shield.The surviving cancer cells must now exit the bloodstream in a process called extravasation.The cancer cells squeeze through the blood vessel wall and enter the surrounding tissue.In their new environment, the cancer cells must adapt to survive. They reverse their earlier structural changes and begin to establish themselves in the tissue.To support their growth, the cancer cells stimulate the formation of new blood vessels through a process called angiogenesis.As the cells multiply and establish a blood supply, they form a secondary tumor, or metastasis.This new tumor can continue to grow and potentially spread to other parts of the body, continuing the cycle of metastasis.Understanding how cancer spreads helps us develop better treatments to stop metastasis.Thank you for learning about cancer metastasis with Spark.E!