Question

What are malignant tumors?

Answer 1

http://www.dictionary.com/browse/malignant-tumor

Answer 2

it is a tumor that invades surrounding tissues, is usually capable of producing metastases, may recur after attempted removal, and is likely to cause death unless adequately treated.

Answer 3

they are cancerous. after a while, increasing amounts of cancerous cells cause tissue damage. This damage cause cancerous cells to enter to the blood. entering into the vessels means that this anormal cells can adapt any place in your body, which is called as metastase.