Hypofractionation and intraoperative irradiation: new possible standards in breast cancer

Breast-conserving surgery (BCS), followed by post-operative whole breast irradiation (WBI), is the current standard for most women with early stage breast cancer. The addition of radiation therapy allows a significant reduction in local recurrences, long term breast cancer mortality and overall mortality, with the greatest benefit in the high-risk group of patients. In spite of these excellent data, in the last years, several institutions are trying to revisit the adjuvant radiation treatment setting, especially with regard to possible changes in the overall treatment time and irradiated volume. This concept has been developed mainly by the clinical application of the modern philosophy of accelerated hpofractionated irradiation and partial breast irradiation. Still to day, often the main obstacle to accept a breast conserving therapeutic strategy is the need of receiving a protracted, at least five but sometimes seven weeks, of radiation therapy. The dogma of applying the standard conventional fractionation has several disadvantages: phycological distress, high financial burden for both the women and health care system, and delayed return to the normal life. To help to alleviate this problem, several institutions have explored new shorter external beam radiotherapy regimens. The delivery of a reduced total dose in a rapid schedule, lasting slightly more than three weeks, did not result in excess of ipsilateral recurrence rate and toxicity, confirming the substantial equivalence with longer fractionation, already reported inother tumor sites. The same policy has been applied at IEO, where the average length of RT cycle after BCS decreased to 20 sessions in the great majority of the patientsand up to 13 in some selected cases, applying the potentially better technical standard, the IMRT (Intensity Modulated Radiation Therapy). Results of these new approaches will presented and discussed. On the other site, Partial Breast Irradiation (PBI) has been tested using various approaches of external beam radiation therapy or single dose intraoperative (IORT) or different brachytherapy techniques. In addition new interesting approaches are emerging to realize a more conformal PBI treatments, both with the use of helical tomotherapy or stereotactic concepts. Some example of this new scenario will be also shown, in order to better integrate PBI in the general management of breast cancer. The main issue is still the proper selection of patients. With some minor differences, both the American and European Societies for Therapeutic Radiology and Oncology (ASTRO & ESTRO) guidelines proposed the selection criteria to define a low-risk group of patients, suitable to be treated in clinical setting. Further efforts have to be made in this field. Molecular subtypes, in addition to conventional clinical and pathological features of the primary tumour, has become an important tool to evaluate the risk not only for distant recurrence and survival, but also for local or local-regional recurrence. Data from randomized trials, including the ELIOT, recently published on Lancet, will be presented and discussed.