For resistant tumors, the therapeutic ratio is:

In the context of resistant tumors, the therapeutic ratio indicates the relationship between the dose that effectively controls or eradicates the tumor and the dose that causes unacceptable damage to surrounding healthy tissue. A therapeutic ratio of less than 1 suggests that the risk of harm to healthy tissue outweighs the benefits of treating the tumor.

When dealing with resistant tumors, it is often more challenging to achieve effective treatment without simultaneously increasing toxicity. As they may require higher doses of radiation to obtain a meaningful response, the potential for harm also escalates. This results in a therapeutic ratio that is less than 1, indicating that the treatment may be more harmful than beneficial in such cases.