How is a malignancy defined?

A malignancy is defined as a cancerous growth that possesses invasive and spreading capabilities. This definition emphasizes two critical characteristics of malignant cells: their ability to invade surrounding tissues and their potential to metastasize, or spread, to distant sites in the body. This invasive behavior is a key feature that distinguishes malignant tumors from benign tumors, which do not invade other tissues and typically remain localized.

The term "malignant" indicates not just uncontrolled cell division but also the aggressive nature of these cells, which can disrupt normal bodily functions, lead to the formation of secondary tumors, and ultimately pose a serious threat to health. Understanding malignancy is essential for diagnosing and treating cancer effectively, as it informs treatment decisions and prognostic assessments.