What is a key feature differentiating cancer cells from normal cells?

Cancer cells are characterized by their ability to metastasize and invade surrounding tissues, which is a crucial distinguishing feature from normal cells. Unlike normal cells, which typically adhere to the boundaries set by their local environment and can only grow and divide within these confines, cancer cells break through these barriers. This ability to invade other tissues and spread throughout the body is what makes cancer particularly dangerous and complicated to treat.

In contrast, normal cells exhibit contact inhibition, meaning they stop dividing when they come into contact with other cells. They have a finite lifespan and undergo programmed cell death when they are damaged or reach the end of their replicative capacity, unlike cancer cells that may evade these processes. While cancer cells often do proliferate rapidly, stating that they do not proliferate quickly would contradict the nature of tumor growth, which is often marked by an uncontrolled and rapid increase in cell numbers. Thus, the ability to metastasize and invade is a hallmark of cancer cells that sets them apart from normal cells.