Risk assessment: Calculating the benefit of RT for individual patients

The primary aim of radiation therapy (RT) for breast cancer is to reduce the risk of local-regional failure (LRF). Although the proportional benefits are substantial, the absolute benefits may be limited in specific patient groups. Moreover, there is a substantial risk of long-term health effects. In the current era of treatment de-escalation, it is therefore crucial to weigh the efficacy of RT against its potential side effects, which should be done in a shared decision-making process.

In this section, two case descriptions are used to discuss the complexities and possibilities of RT risk assessment in light of existing prediction tools and current developments. Ideally, predicted risks of LRF are discussed in the context of tumour- and treatment-related characteristics as well as the patient’s personal situation and wishes. As prediction tools on its own turn out not to be sufficient to adequately assess the individual benefits and harms of RT, more efforts should be done to incorporate multigene assays, information on a patient’s intrinsic susceptibility to RT and RT-induced side effects in RT risk assessment. Finally, patient decision aids should be considered in order for patients to better understand the benefits and harms of RT treatment.