The mechanisms of vascular invasion involve multiple steps:
1. Tumor Angiogenesis: Tumors stimulate the formation of new blood vessels to supply nutrients and oxygen, a process known as angiogenesis. 2. Degradation of the Extracellular Matrix: Malignant cells produce enzymes such as matrix metalloproteinases (MMPs) that degrade the extracellular matrix, allowing them to penetrate blood vessel walls. 3. Intravasation: Malignant cells enter the lumen of blood vessels. 4. Circulation: Once in the bloodstream, malignant cells can travel to distant sites. 5. Extravasation: Malignant cells exit the bloodstream and invade new tissues, forming secondary tumors.
