Seminars

Counting what really counts: Estimating therapeutic benefit from radiation oncology interventions

Radiation therapy has been used for more than a century as a major treatment modality for localized or regional cancer. While absolute radioresistance does not exist, the probability of controlling the tumor is limited by the side-effects of radiation therapy. The dose of radiation delivered can be titrated accurately and there is a relatively steep relationship between this dose and both the incidence of tumor control and the probability of developing a specific grade of complication. All of
this means that the choice of treatment intensity in an individual patient should be based on a careful consideration of the risks and benefits of therapy. Ideally, a quantitative measure of this risk:benefit trade-off, often loosely referred to as the therapeutic ratio, should be used as the primary endpoint in clinical trials involving radiotherapy. Over the
years, many attempts have been made to quantify therapeutic ratios and I will briefly review some these in the talk. A novel approach will be presented that tries to work around some of the problems with previous measures and examples of how this can be applied in practice are presented. Finally, I will briefly discuss attempts to use quality-of-life endpoints and health economics endpoints as summary measures of clinical utility.