The efficacy of IORT (intraoperative radiotherapy) for early advanced breast cancer depending on the time delay of external beam irradiation (EXRT) post conservative breast surgery (CBS)

Introduction. The following study focuses on the efficacy of the IORT (14.4 izoGy2.0) as part of conservative surgery with adjuvant EXRT (50 Gy in 25 fractions) for low risk 109 early breast cancer patients and 106 intermediate or nonlinear high risk patients with adjuvant chemoradiation or chemotherapy followed by the EXRT. Material and methods. The accumulation of the rates of local recurrences (LR) and distant metastases (DM) are characterized by nonlinear but two-phase curves. Results. During the first 5 years, 67% of all LR, and only 43% of all DM occurred, and between the 8th and 10th years the LR curve steeply increases by 25% and the DM by 48%. Conclusion. This suggest that a 5-year follow-up is too short and should be extended to 10 years. Among the analyzed prognostic factors, the time interval (TI) between IORT and adjuvant EXRT has occurred the major prognostic risk factor. If the TI is extended over 60 days (delayed EXRT), the LR and the DM risk undergoes a3–10 fold increase. Concurrent CH-EXRT significantly lowers local and distant failures, compared with delayed EXRT after completing CHT. Therefore, delayed EXRT completely ruins the expected efficacy of the IORT.