Which of the following is NOT considered a hallmark feature of cancer cells?

• A. Controlled growth
• B. Genetic instability
• C. Undifferentiated cells
• D. Resistance to apoptosis

Answer: (A)

Cancer cells are defined by their ability to proliferate without normal constraints, resisting the body's checks on growth. That means they grow uncontrollably because signaling pathways and tumor suppressor mechanisms that normally keep cell division in check are bypassed or mutated. Genetic instability provides the ongoing source of mutations that drive cancer progression, so it’s a hallmark. Cancer cells also tend to be undifferentiated or poorly differentiated, reflecting a loss of specialized features, which is another common hallmark. They also frequently resist apoptosis, enabling survival despite cellular stresses that would normally trigger cell death. Therefore, describing growth as controlled contradicts how cancer cells behave, making it not a hallmark.