American Board of Surgery Qualifying Exam (ABS QE) Practice Test

In regards to cell cycle sensitivity, what is the critical aspect of the M phase?

1. Low metabolic activity increases sensitivity

2. High repair capability decreases sensitivity

3. Cells are actively dividing and vulnerable to damage

4. It represents a phase of cell death

The correct answer is: Cells are actively dividing and vulnerable to damage

The M phase, or mitotic phase, is characterized by the active division of cells. During this phase, the cellular machinery is engaged in processes such as chromosome segregation and cytokinesis, making the cells particularly vulnerable to agents that can damage DNA or disrupt these processes. Since cells are actively undergoing division, they are sensitive to treatments that affect the mitotic spindle or DNA replication, such as chemotherapy drugs like taxanes and vinca alkaloids. This heightened sensitivity is crucial for the effectiveness of certain cancer treatments, as these therapies aim to target rapidly dividing cells, a hallmark of many cancer types. In contrast, other phases of the cell cycle may show different thresholds of sensitivity based on metabolic activity or cellular repair mechanisms. Therefore, the defining aspect of the M phase is the active division of cells, which indeed makes them more susceptible to damage from various therapeutic agents.