Prognostic factors for local recurrence and radioresistance

Generally accepted risk factors for the development of local recurrence are, besides tumor-involved margins: young age, large tumor size and high histological grade. These factors are, however, not sufficient. Using oligonucleotide array, we have found a gene expression profile associated with the development of local recurrences, despite postoperative radiotherapy, after breast conserving surgery (radio resistance), and that, with less statistical strength, identified patients not in need of radiotherapy.
A validation study, using frozen breast cancer tissue, has been started and by using second generation sequencing techniques we are also evaluating the possibility to distinguish true local recurrences from new primary tumors.
Biomarkers involved in the radiosensitivity and development of local recurrences will also be studied in tumors from patients who have participated in a randomized clinical trial, evaluating the importance of radiotherapy after breast conservation surgery. Paraffin-embedded material from both the primary tumor and the local recurrence has been collected from almost 1,000 patients participating in this trial.