Intra-operative radiation therapy (IORT) in the treatment of breast cancer- a new therapeutic alternative in the conservative treatment of breast cancer? Its potential role and future perspectives, experiences from the European Institute of Oncology(EIO), Milan

Background: External beam radiation therapy (EBRT) represents an integral c omponent of breast-conserving treatment. In published series it has been de monstrated that the external boost can be replaced by intraoperative radiot herapy (IORT) where irradiation at a single dose from 10 up to 15 Gy was sa fely delivered directly to the tumor bed. Patients and Methods: At the European Institute of Oncology, Milan, we init iated a dose escalation study to investigate the feasibility of applying si ngle doses of IORT from 10 Gy up to 22 Gy. A portable IORT equipment with d ifferent electron energies was used. From July to December 1999, a total of 65 patients with T1-2 (max. 2.5 cm) N0-1 breast cancer, median age 58 year s (range 33-80 years) was treated. Ten patients received 10 Gy, eight patie nts were treated with an IORT of 15 Gy, eight received 17 Gy, six had 19 Gy , and 33 were treated with 21-22 Gy. Patients with 10 and 15 Gy received an additional EBRT of 44 and 40 Gy, respectively. In all other patients IORT was the sole radiation treatment. Results: No acute side effects or intermediate untoward effects after a fol low-up from three to nine months related to IORT were observed. Conclusions: Since the applicator can be safely placed under the control of the surgeon and radiotherapist IORT has the potential of accurately treati ng the tumor bed. Skin and subcutaneous tissue are not irradiated thus decr easing the potential risk of fibrosis and eventually obtaining a better cos mesis. With IORT single doses of 22 Gy being equivalent to a 60 Gy EBRT can safely be delivered. Even so the average time of operation was prolonged b y around 20 minutes IORT application ultimately improves the quality of lif e of the patients in shortening overall treatment. Long-term follow-up is n ecessary to demonstrate whether large single doses of IORT might have the p otential of sufficient local tumor control without major side effects. As a future perspective a randomized trial comparing EBRT with IORT as sole tre atment will be performed.