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

What does fractionated radiation therapy allow for regarding tumor cells?

1. Redistribution of tumor cells in the cell cycle

2. Immediate destruction of all tumor cells

3. Increased patient recovery time

4. Essentially guarantees a cure

The correct answer is: Redistribution of tumor cells in the cell cycle

Fractionated radiation therapy allows for the redistribution of tumor cells in the cell cycle, making it an effective treatment strategy. Tumor cells do not all divide simultaneously; they exist in different phases of the cell cycle at any given time. Radiation therapy is particularly effective during certain phases of the cell cycle, specifically during mitosis (when the cell divides). By dividing the total dose of radiation into smaller, fractionated doses, this therapy gives normal cells time to recover while exposing tumor cells to subsequent doses during the phases when they are most vulnerable to the effects of radiation. This approach not only enhances the therapeutic effect but also minimizes damage to surrounding healthy tissue. Immediate destruction of all tumor cells is unrealistic because some cells may be in a resting phase or be able to repair damage. Increased patient recovery time is not an objective of the treatment but rather a consequence of allowing normal tissue to recover while still applying therapeutic doses to the tumor. Although fractionated radiation therapy can lead to significant tumor reduction and sometimes cure, it does not guarantee a cure, as results can vary based on tumor type, stage, and individual patient factors. Thus, the best answer focuses on the dynamic nature of tumor cells’ responses during treatment.