Which characteristic is most associated with malignant cancer cells compared with benign cells?

• A. Rate of growth
• B. Ability to spread
• C. Cell contents
• D. Ability to cause death

Answer: (B)

The key idea is that cancer cells gain the ability to spread from the original tumor to other parts of the body. This metastasis, traveling through blood or lymphatic vessels and invading new sites, is what makes malignant cells dangerous and distinguishes them from benign cells, which stay localized and form only a single, contained mass. Benign tumors tend to grow slowly and remain encapsulated, not invading surrounding tissues or establishing new tumors elsewhere. Growth rate alone isn’t a reliable differentiator since malignant tumors can grow at various speeds, and differences in cell contents aren’t the defining feature either. While metastasis can lead to death by disrupting vital organs, that outcome isn’t a property of the cells by itself; the standout trait is the capacity to spread.