What makes a tumour malignant or benign?

A tumor is considered malignant or benign based on its characteristics and the context in which it exists. Malignant tumors are typically characterized by rapid growth, invasion into surrounding tissue, and a tendency to metastasize (spread throughout the body). Benign tumors, on the other hand, generally lack these features and remain localized to their area of origin.

The primary difference between malignant and benign tumors lies in how they behave. Unlike benign lesions, malignant ones can continue to grow locally in size due to unchecked cell division. They also tend to invade nearby tissues through direct physical contact as well as via local blood vessels and lymphatic systems (a process called “metastasis”). This means that unlike a benign tumor which is static - almost like a cyst - a malignant one will spread further unless treated appropriately; this ability to spread widely makes it particularly dangerous.

Malignancy is generally caused by an accumulation of genetic mutations resulting from DNA damage accumulated over time from both internal processes such as errors during cell division or external factors such as exposure to carcinogens or radiation. These mutations modify gene expression levels or increase the number of copies of existing genes thus promoting cancer development. As cells with mutated genes divide uncontrollably and form a mass (tumor), normal cells surrounding them die leaving an environment rich in nutrients that fuel further proliferation leading ultimately to disease progression if left untreated for long enough periods of time.