Ablative SBRT in Elderly BC Patients

Stereotactic body radiotherapy (SBRT) is a modern radiotherapy technique, through which extremely high doses of irradiation are delivered in a very precise manner, within a few fractions. SBRT is increasingly used into clinical practice because it can provide excellent local control, comparable to surgery, in many tumor locations, such as lung, liver or bone. Efforts to develop it for BC treatment are promising, as it is safe, convenient, and effective. To date, SBRT for BC has been developed as an alternative method of partial-breast irradiation (PBI) in the pre- or post-operative setting. Therefore, the doses tested are comparable to the conventional doses used with surgery although its potential as sole local treatment for BC remains unknown. Higher SBRT doses are expected to permit obtaining an ablative effect on tumor and be suitable as an alternative to surgery, but this hypothesis has yet to be tested. The aim of the present study is to prove the feasibility of SBRT as an ablative treatment in early breast cancer (BC). The primary objective is to find the maximum tolerated dose of SBRT that can be safely administered in inoperable patients with BC, the majority of whom are elderly or oldest old. The overall objective is to determine whether high precision, dose- and fractionation- adapted SBRT is feasible and safe in inoperable patients with BC. The dose and fractionation-adapted SBRT regimen permits to test feasibility in different tumor sizes. The primary objective of this study is to establish the maximum tolerated dose (MTD) that can be delivered with a single or few (up to 5) fractions of SBRT in inoperable patients with BC.