What therapeutic ratio would be expected to provide the highest probability of cure?

The therapeutic ratio is a measure of the relationship between the desired therapeutic effect and the untoward toxic effects of treatment. In radiation therapy, this ratio is crucial because it helps evaluate how effectively a treatment can kill cancer cells while minimizing damage to surrounding healthy tissues.

A therapeutic ratio greater than 1 indicates that the treatment is more effective at targeting cancer cells than causing harm to normal tissues. As the ratio increases, so does the likelihood of achieving a successful outcome with fewer side effects, thereby improving the chances of cure.

In this context, a therapeutic ratio of 1.75 suggests a significantly greater effectiveness in treating the tumor compared to the potential for adverse effects. This higher ratio implies that the treatment is well-tolerated and has a substantial likelihood of destroying cancer cells, thus providing the highest probability of cure compared to the other options listed.

Lower therapeutic ratios such as 0.85, 1.0, or even 1.45 suggest less effective treatments or higher chances of side effects relative to the therapeutic gain, making them less desirable for achieving optimal results in cancer treatment. The higher the ratio, the better the treatment's balance of efficacy versus safety, making the option with 1.75 the most favorable for maximizing therapeutic success.