The relevance of translational research for radiotherapy in breast cancer

In several EORTC trials the role of radiotherapy in breast cancer has been examined. It has been shown that patients with DCIS radiotherapy have a reduced risk of both invasive and noninvasive ductal cancer recurrences. For patients with early breast cancer we demonstrated that a boost of 16 Gy reduces the risk of recurrence in the breast by nearly a factor of 2, and is especially clinically relevant for patients younger than 50 years. In locally advanced breast cancer patients, a similar reduction in the local recurrence rate was seen when chemotherapy or hormontherapy was added to radiotherapy.

Despite these achievements, we are not able to select enough patients with the need for radiotherapy, and the required dose in this patient population. New techniques, such as comparative genomic hybridization assay, DNA microarrays, functional DNA screens and functional yeast assays, may guide us more precisely toward the optimal treatment strategy in individual patients. Furthermore, these research lines offer the possibility to investigate the mechanism of action, and therefore lead to the development of new drugs that will potentiate the cell-killing effect of radiotherapy. This lecture focuses on the integration of these new techniques in relation to the obtained results from the above-mentioned clinical trials.