A higher growth fraction results in what?

A higher growth fraction in a tumor refers to the proportion of cancer cells that are actively dividing compared to those that are in a resting or non-dividing state. This characteristic plays a significant role in the effectiveness of chemotherapy, as many chemotherapeutic agents target rapidly dividing cells.

When there is a higher growth fraction, there is a greater likelihood that these drugs will be able to effectively kill the cancer cells because more of the cells are in phases of the cell cycle that are sensitive to the effects of chemotherapy. Cells that are in the S phase (synthesis phase) or mitosis (M phase) are particularly vulnerable to agents that interfere with DNA replication or mitosis. Therefore, a higher growth fraction correlates with an increased exposure of dividing cells to these specific cytotoxic agents, enhancing the likelihood of cell kill.

In summary, a higher growth fraction increases the effectiveness of cytotoxic drugs due to the larger number of cells that are actively dividing and thus susceptible to treatment, making this the correct interpretation of the relationship between growth fraction and chemotherapy efficacy.