What defines cancer in terms of cell growth?

Cancer is fundamentally defined by uncontrolled mitosis, which leads to the rapid and unregulated growth of cells. In a healthy organism, cell division is tightly regulated through various mechanisms that ensure cells grow, divide, and die in a controlled manner. This regulation includes checks and balances that prevent excessive proliferation of cells.

When cells become cancerous, they undergo mutations that disrupt these regulatory processes, resulting in uncontrollable cell division and growth. This unchecked proliferation can lead to the formation of tumors and, eventually, the spread of cancer to other parts of the body. Therefore, the hallmark characteristic of cancer is this loss of control over the cell cycle, which is accurately captured by the concept of uncontrolled mitosis.

Choices such as controlled cell division and normal cell behavior reflect healthy cell function and are not representative of cancerous growth. Inhibited cell growth pertains to conditions where cell division is suppressed, which is opposite to what occurs in cancer. Thus, the defining feature of cancer lies in its inherent tendency for uncontrolled division, making it the correct choice.