**Question:** Radiosensitive tumor is -

A. A tumor with a high cell division rate
B. A tumor with a low capacity to repair DNA damage
C. A tumor with a high rate of angiogenesis
D. A tumor with a high rate of necrosis

**Core Concept:** Radiosensitivity in tumors refers to the ability of tumor cells to survive and grow following exposure to ionizing radiation. The radiosensitivity of a tumor depends on its cell division rate and its capacity to repair DNA damage.

**Why the Correct Answer is Right:** A radiosensitive tumor is a tumor with a high cell division rate, making the cells more susceptible to DNA damage and impairing the ability to repair the damage. This leads to a higher likelihood of radiation-induced cell death and slower tumor growth or regression after radiation therapy.

**Why Each Wrong Option is Incorrect:**

A. **Radiosensitive tumor is not necessarily a tumor with a high cell division rate.** While a high cell division rate increases radiosensitivity, there are other factors involved as well, such as DNA repair capacity.

B. **A tumor with a low capacity to repair DNA damage is not necessarily radiosensitive.** The radiosensitivity depends on cell division rate and repair capacity, not just repair efficiency.

C. **A tumor with a high rate of angiogenesis is not inherently radiosensitive.** Radiosensitivity depends on cellular characteristics, not on tumor vascularization or other factors like inflammation or immunity.

D. **A tumor with a high rate of necrosis is not radiosensitive.** Radiosensitivity is determined by cell division rate and repair capacity, not by necrosis or apoptosis rates.

**Clinical Pearl:** Understanding tumor radiosensitivity is crucial for selecting appropriate treatment strategies. A high radiosensitivity indicates that radiation therapy can be more effective, while low radiosensitivity may require alternative treatments. Correctly assessing radiosensitivity can lead to improved cancer management and patient outcomes.