A tumor that spreads to other tissues is what?

A tumor that spreads to other tissues is known as a malignant tumor. These tumors have the ability to invade surrounding tissues and metastasize, meaning they can spread to distant organs via the bloodstream or lymphatic system. This characteristic distinguishes malignant tumors from benign tumors, which do not spread and are typically less aggressive. Malignant tumors are often associated with cancer and can pose significant health risks.