Final answer:
Tumors that spread to other parts of the body through blood are known as malignant tumors. The process is called metastasis, leading to secondary tumors called metastases, most commonly in the brain, lungs, bones, and liver.
Step-by-step explanation:
Tumors that invade other tissues and can spread to other parts of the body through blood to form secondary tumors are known as malignant tumors or cancerous tumors. This process is referred to as metastasis, and the secondary tumors that develop are called metastases. Different types of cancers have a tendency to metastasize to particular organs, with the most common sites for metastasis being the brain, lungs, bones, and liver. Malignant tumors can shed cells into the bloodstream, which then travel and initiate new tumor growth elsewhere in the body. This spreading of cancer cells is the primary reason why cancer becomes difficult to treat and has a poor prognosis.